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MOTIVATING SAFETY BELT USE AT A HOSPITAL SETTING:
TOWARDS AN EFFECTIVE BALANCE BETWEEN
EXTRINSIC INCENTIVES AND INTRINSIC COMMITMENT
by
James G. Nimmer
Thesis submitted to the Faculty of the Virginia Polytechnic Institute and
State University in partial fulfillment of the requirements for the degree
of
MASTER OF SCIENCE
in
Psychology
APPROVED:
E. Scott Geller, Chairman
Richard A, Winett Stephen J. Zaccaro
October 1985
Blacksburg, Virginia
MOTIVATING SAFETY BELT USE AT A HOSPITAL SETTING:
TOWARDS AN EFFECTIVE BALANCE BETWEEN
EXTRINSIC INCENTIVES AND INTRINSIC COMMITMENT
by
James Glenn Nimmer
(ABSTRACT)
Recent research on attempts to motivate large-scale safety belt use
has documented a number of shortcoming, including limited long-term
evaluation data, excessive costs, short-lived intervention effects, and
program delivery by outside a~encies rather than indigenous personnel.
The present study attempted to overcome these disadvantages.
Specifically, the "Buckle-up for Bucks" safety belt promotion campaign
conducted at a community hospital incorporated the following: a)
indigenous hospital staff as program sponsors, delivery agents, and co-
coordinators; b) a year-long program evaluation; and c) a combination
incentive and commitment-based intervention program.
Directed and coordinated through the Office of Community
Relations, the hospital-based intervention included awareness sessions,
randomly determined five-dollar a week cash incentives, and a
commitment-based pledge card strategy. To be eligible to win the
incentives, the staff members met the following contingencies: a) wore a
safety belt; b) signed a pledge card; c) displayed the signed pledge
card on their dashboard; and d) pledged for a duration that ensured
eligibility.
The evaluation data were collected for four phases: baseline,
intervention, withdrawal, and a long-term, follow-up. For the overall
sample, usage increased from a baseline mean of 15.6% to 34. 7% during
the intervention, decreased to 25.6 at withdrawal, and increased to a
long-term follow-up mean of 28.6%. For the Pledge card signers and
the Non-singers, usage increased from baseline means of 29.4 90 and
11.8% to intervention usage rates of 75.1% and 17. 7%, respectively,
demonstrating that the intervention had a differential effect on the
signers and non-signers. Withdrawal and Follow-up usage rates were
56.0% and 44.9% for the Pledge group, and 17.2% and 22.1% for the
Non-pledge group.
A chi-square test for white noise indicated the data were
autocorrelated. A time-series analysis was conducted to remove the
serial dependency. Statistical significance of the intervention was
examined from the time-series perspective and traditional analysis of
variance procedures. Differences between approaches are addressed
and theoretical explanations for the intervention effects are considered.
Finally, suggestions for future research are offered.
ACKNOWLEDGEMENTS
I would like to gratefully acknowledge a number of individuals who
made invaluable contributions toward the completion of this thesis.
Most notably, I would like to thank Dr. E. Scott Geller, whose
"commitment to quality", guidance and friendship has contributed
immensely to the completion of this manuscript and, more importantly,
to my professional development. Appreciation and sincere thanks are
gratefully extended to Ors. Steven Zaccaro and Richard Winett for
extending their expertise and support. I would also like to thank the
staff at Radford Community Hospital and in particular to Susan
Vengrin, the director of Community Relations; without their
contributions, this project was not a possibility.
Thanks is also extended to the following individuals who spent
countless hours assisting me in the organization and management of this
project: Agustin Reyna, computer programmer extraordinair; Sandy
Forrest, data manager extraordinair; Steve Clarke, general
extraordinair; Cheryl Bruff, extra-extraordinair; Fritz Streff, always
there extraordinair. Their support made this project almost a painless
success. To the U. S. Department of Transportation and the Virginia
Division of Motor Vehicles for funding the project, a grateful thank
you.
iv
A very personal and special thanks is extended to a super group
of friends who have attained my deepest friendship and greatest
personal and professional respect. In order, but not alphabetically:
Cheryl Bruff, tears cannot describe; Steve Clarke, best "overall"; Phil
Maddox, the leacherous guy and most incredibly tolerant; Steve Walker,
boundless friendship and laughter; Fritz Streff, friendship,
understanding and dearly supportive; Mike Kalsher, northern buddy;
Carolee Miller, subtle but significant; Jim Rudd, friendship; Fran
Wolleson, friendship; Tim O'Keefe, friendship; Gene Stone, guidance
and friendship; and certainly not the least Dr. Joe Sgro, guidance and
friendship.
Finally, want to express sincerest gratitude and heartfelt thanks
to my mother, Carol Nimmer, and my brothers Glenn ar.d Ken Nimmer.
Their unselfish support, love, and respect has helped me achieve the
greatest milestone in my career.
V
Table of Contents
Page
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
Acknowledgements ................................................... iv
List of Tables ................................. ..................... viii
List of Figures ...................................................... ix
Problem Definition ................................................... 1
Standard Strategies for Motivating Safety Belt Use ................... 2
Educational Approaches ......................................... 2 Engineering Approaches ........................................ 4 Legal Approaches ............................................... 6
Innovative Strategies for Motivating Safety Belt Use ................. 7
Reinforcement Theory Revisited ................................. 7 Survey of Applied Literature ................................... 9 Limitations ..................................................... 10 Commitment Paradigm ........................................... 12 Theoretical Commitment Perspectives ............................ 13 Survey of Applied Literature ................................... 17 Limitations ..................................................... 20
Hypotheses ..................... ..................................... 22
Method .............................................................. 23
Subjects and Setting ........................................... 23 Design ......................................................... 23 General Observation Procedure ................................. 23 Baseline ........................................................ 24 Intervention .................................................... 25
Awareness Sessions ........................................... 26 Incentive Program and Commitment Strategy .................. 27
Withdrawal ..................................................... 29 Follow-Up ...................................................... 29
vi
Results . .................................•........................... 30
I nterobserver Reliability ........................................ 30 Description of Shoulder Belt Usage ............................. 32 Interrupted Time Series Analysis ............................... 37
Identification ................................................. 39 Estimation .................................................... 42 Diagnosis ..................................................... 44
Interpretation of Time Series Results ........................... 46 Analysis of Variance ............................................ 49
Discussion . .......................................................... 52
General Theoretical Issues ...................................... 53 Specific Analytic Issues ........................................ 61
References .......................................................... 67
Appendix A ......................................................... 73
Data Collection Sheet for Daily Collection of Safety Belt Usage
Appendix B ......................................................... 75
Buckle:-up for Bucks Campaign Bulletin
Appendix C ......................................................... 77
Pledge Card
VITA ................................................................ 79
vii
List of Tables
Table
1. Results From the lnterobserver Reliability Analysis Including
Page
Frequencies and Percent Agreements ........................... 31
2. Means and Frequencies of Observations for Pledge Card Signers and Non-pledge Card Signers as a Function of Experimental Condition ............................ 36
3. Results From the Estimation Procedure of the Time Series Analysis for Pledge Card Signers, Non-pledge Card Signers, and Overall ......................... 43
4. Results From the Diagnostic Procedure of the Time Series Analysis for Pledge Card Signers, Non-pledge Card Signers, and Overall ......................... 45
5. Comparison of Treatment Effects Detected by the Analyis of Variance and Time Series Procedures ................................... 64
viii
List of Figures
Figure
1. Mean Daily Shoulder Belt Usage for the Overall Sample as a
Page
Function of Experimental Phase ................................ 33
2. Mean Daily Shoulder Belt Usage of Pledge Card and Non-pledge Card Signers as a Function of ~xperimental Condition ....................... 35
3. Means and Confidence Intervals of the Time Series Analysis for Pledge Card Signers, Non-pledge Card Signers, and Overall ................ 47
ix
Problem Definition
Every automobile produced in the U.S. since 1968 has been
equipped with some combination of a shoulder/lap belt safety system
(Nichols, 1982). Designed for the explicit purpose of protecting
occupants in an accident, the current lap and shoulder belt combination
has more injury-reduction and life-saving potential than all other
occupant protection systems, including the airbag and padded interiors
(Federal Register, 1983; Nichols, 1982; Sleet, 1984). In fact, it is
estimated that 55% of all traffic fatalities and 65% of all injuries would be
prevented if safety belts were used ( Federal Register, 1983); yet, as
late as 1981 only 14% of the U.S. population availed themselves to these
proven safety devices (Bigelow, 1982). This infrequent use of shoulder
belts is responsible, at least in part, for: (a) the estimated 45,000
deaths and 500,000 injuries that occur each year on our nation's
highways (Bigelow, 1982), (b) the fact that vehicle accidents are the
leading cause of fatalities among persons aged 5 to 34 (Sleet, 1984), (c)
the cumulative American financial liabilities in excess of $60 billion per
year (Pabon, Sims, Smith, & Associates, 1983), and (d) the
immeasurable human emotional and physical suffering. These statistics
provide compelling evidence for the importance of developing strategies
for motivating safety belt use.
In the last decade the problem of low safety belt usage has
received increased attention; and subsequently, there has been a
growing effort across the nation to increase safety belt use (Bigelow,
1
2
1982). Spearheading this campaign is the National Highway Traffic
Safety Administration (NHTSA). In May 1979, NHTSA formed an
interdisciplinary committee of experts in transportation safety to
evaluate strategies for motivating safety belt use. Several large-scale
strategies for increasing safety belt use were reviewed. The strategies
can be classified as emphasizing educational tactics, human factors
engineering,· governmental policies and legislative mandates, and
incentive programs.
Standard Strategies for Motivating Safety Belt Use
Educational Approaches
The educational approach focuses on increasing safety belt usage
by making people aware of the potential benefits of wearing safety belts
and the potential costs of driving unbuckled. Such educational
programs are specifically designed to influence behavior change by
increasing public awareness, changing public knowledge and attitude
levels, and supporting messages conveyed from other sources (Nichols,
1982). A variety of educational approaches including films, slide
shows, school programs, small group discussions, and pamphlets have
been applied to promote safety belt use. The effectiveness of the
educational approach has been enhanced to some extent th rough
promotional mediums such as radio, television, newspapers, signs, and
billboards; their impact, however, has been equivocal.
Several researchers have found the success of large scale
educational strategies for safety belt promotion to be minimal or
nonexistent (e.g., Cunliffe, DeAngelis, Foley, Lonero, Pierce, Siegle,
3
Smutylo, & Stevens, 1975; Phillips, 1980; Geller, 1981). For example,
Cunliffe et al. reported that a comprehensive educational effort
involving a multimedia public education campaign in Ontario, Canada had
no effect on safety belt usage after being in effect for six months.
Phillips (1980) reported no significant gains in belt usage as a result of
a nine-month, industry-based educational program which included
newspaper articles, posters, booklets, a film, and a demonstration.
Similarly, Geller (1981) demonstrated that showing a safety belt
promotion film at an industrial site had no effect on shoulder belt usage
in spite of increased verbal reports of intentions to wear safety belts.
In other countries, research has demonstrated that multimedia,
educational efforts can significantly increase safety belt usage. Nichols
(1982) described two such programs. One was a six-week television
and print campaign in Great Britain that increased safety belt usage
from 12 percent at baseline in 1971 to 26 percent in 1972. Nine annual,
six-week campaigns raised the usage level to a two-time high of 33% in
1976 and 1980 ( ranging 26 to 33 percent for the ten-year period). The
other was a four-year (1971-1974) Swedish campaign that raised safety
belt usage from 15% at baseline in 1971 to 36% by the end of 1974.
However, both of these campaigns were hindered by unwieldy costs that
made them difficult if not realistically impossible to replicate without
extensive governmental support.
Unfortunately, just knowing the advantages and disadvantages of
engaging in a specific behavior is often not a sufficient motivator.
Many are aware of the persistence of some people in pursuing
4
personally destructive habits in light of overwhelmingly convincing
medical evidence. Thus, other strategies are necessary to supplement
the educational approach to safety belt promotion.
Engineering Approaches
The engineering approach is one that attacks ·the problem of low
safety belt usage through technology and human factors engineering.
For example, beginning in 1974 all passenger vehicles were required by
federal mandate to have an ignition/interlock system that prohibited
occupants from starting the engine until their safety belts were
buckled. Nichols (1982) claimed that the 1973 interlock rule had more
impact on safety belt use than any prior U.S. effort. The benefits of
the decision to enhance safety belt usage through installation of
interlock systems is well-documented. Geller, Casali and Johnson (1980)
and Nichols (1982) reported the safety belt use of their samples of 1974
motor vehicles to be at 100 and 74 percent, respectively. However,
Geller et al. found that 57% of the vehicles with ignition interlocks had
disconnected or circumvented systems (e.g. , the driver was sitting on
a buckled belt). Nichols (1982) also claimed that a national belt usage
rate of 25 percent in 1974 model cars had been obtained.
Unfortunately, as a possible result of strong public reactio'n, the 1973
interlock rule was rescinded in 1974. Safety belt usage rates have
witnessed a steady decline since the legislative act (Nichols, 1982).
Other engineering modifications have been more acceptable to
consumers (e.g., buzzer/light reminder systems, passive restraint
systems, and airbags); however, these devices have been either less
5
effective in raising safety belt usage or in protecting occupants. One
type of safety system that has had some success is the "unlimited"
buzzer/light reminder system. In one study, 54.3 90 of those drivers
possessing an operational system were reported to have been wearing
safety belts (Geller, Casali, & Johnson, 1980). The key word is
"operational", as several researchers have reported that such systems
are frequently defeated by disconnection or circumvention (Geller, et
al. 1980; Robertson, 1975; Westefeld & Phillips, 1976). Another type
of system, a "limited" buzzer system is less intrusive than its
counterpart, but also is apparently less effective. Geller et al. (1980)
reported that the safety belt usage level among drivers with the limited
system was not significantly higher than drivers with only a light
reminder system.
Automatic shoulder belts and dashboard-mounted airbags represent
common examples of passive restraint systems. They are both limited,
however, in their capacity to protect motorists. The shoulder belt
system allows occupants in certain types of accidents to slide out from
underneath the shoulder belt, and the automatic airbags provide
adequate protection only in frontal collisions (Transportation Research
Board, 1980). In a crash test, NHTSA compared the protection
capacity of airbags and a manual safety belt system. Their results
indicated that safety belts provided greater protection than airbags
against chest injuries suffered in frontal collisions. (Federal Register,
1983).
Legal Approaches
6
Legal approaches to motivating safety belt use consist of
compulsory seat belt usage laws, that when enforced, fine vehicle
occupants for not wearing their safety belts. The legislative mandate,
currently in use in 29 countries around the world, (e.g., Australia,
Canada, England, France, Germany, Japan, Sweden) has resulted in
post-law usage rates of 70-90 percent (Nichols, 1982; Pierce, Toomer,
Gardner, Pang, & Orlowski, 1976). While probably the most effective
large-scale strategy, the imposition of laws is difficult in many
situations, because of: (a) controversial public reaction, (b) stringent
and costly law enforcement, and (c) the necessity of incorporating
substantial public information and education programs (Nichols, 1982).
One way of increasing the likelihood of legislative action, is to
raise public support th rough comprehensive mass-media campaigns.
Nichols (1982), in response to the enactment of safety belt legislation in
other countries, stated "nearly all reviewers of safety belt usage laws
have pointed out the importance of substantial public information and
education programs prior to the pursuit of such legislation" (p. 79).
However, until people begin wearing safety belts by their own volition
or there are laws requiring occupants in all states to buckle-up
(although even with a national policy, compliance is not assured), there
exists a clear need to develop cost-effective strategies for long-term
and large-scale increases in safety belt usage.
The strategies reviewed above are alike in that in the final
analysis people did not buckle up unless an externally induced
contingency was applied. The legal strategy penalizes people by fining
7
them for not buckling up. The engineering approach constructs
systems that physically restrain people, without providing an option for
their consent. The educational tactics, if unaccompanied by the threat
of legal action, tend to be too costly to be of practical utility. Not
only must new techniques be developed that motivate safety belt use,
but from a more humanistic perspective, these methods should still
maintain at least the "perception" of freedom of choice. Two strategies
meeting these criteria and becoming increasing recognized are incentive
and commitment approaches. In the following sections these two
strategies are reviewed with respect to their theoretical underpinnings,
empirical applications, and practical limitations.
Innovative Strategies for Motivating Safety Belt Use
Reinforcement Theory Revisited
Incentives and their concomitant rewards provide positive
reinforcement for increased safety belt usage. In a prototypical
incentive-based, reward paradigm people are offered a reward or an
opportunity to receive a reward contingent upon performing a specific,
predetermined behavior. As an example, researchers have increased
safety belt usage by offering monetary rewards to drivers who are
observed wearing their safety belt (the specific behavior). People may
choose to buckle up or they may decide not to act -- the choice is
theirs.
Reinforcement theory has its roots in the writings of E. L.
Thorndike, who, with his early statement of the law of effect (1911),
defined reinforcement theory of motivation.
8
Of several responses made to the same situation, those which are accompanied or closely followed by satisfaction to the animal will, other things being equal, be more firmly connected with the situation, so that when it recurs, they will be more likely to recur; those which are accompanied or closely followed by discomfort to the animal will, other things being equal, have their connections with that situation weakened, so that, when it recurs, they will be less likely to occur. (p.244)
Although the mechanistic overtones were later . supplanted by
operational definitions, the spirit of the law of effect has remained
unchanged. Other early researchers made substantive contributions to
the ontogeny of reinforcement theory (e.g., Pavlov, Watson, Bechterev,
Toleman, Guthrie, Hull, Spence etc.); however, it is neither the
purpose nor the intent of this investigation to provide a pedagogical
account of the history of reinforcement theory. One researcher's
contribution, however, because of its specific relevance to incentive
strategies and the current investigation, is briefly reviewed.
B. F. Skinner (1938, 1953, 1958) articulated the operant approach
to reinforcement theory. His orientation is fundamentally based on the
direct observation of the rate of targeted behaviors as a function of the
classical ASA paradigm or a derivative thereof. Skinner spearheaded
the behavioral orientation. His rejection of inferred constructs such as
needs, drives, motives, and cognitions, and his adoption of the study
of overt behaviors as the only appropriate methodology, defined the
field of Applied Behavior Analysis. For Skinnerians, positive
reinforcement refers to the application of a stimulus contingent upon the
performance of a behavior that results in an increase in the rate or
probability of that behavior. Likewise, negative reinforcement refers to
9
the removal of a stimulus that is associated with a subsequent increase
in the rate or probability of responding. Reinforcement is viewed as
the consequence of a response that serves to maintain or increase the
rate of that response.
Survey of Applied Literature
Incentive strategies which offer rewards for the engagement of a
specific behavior represent a prototype of the positive reinforcement
paradigm. The current nationwide effort to increase safety belt use
has received much support from the application of incentive strategies.
The beneficial impact of safety belt incentive strategies has been
demonstrated in a variety of environmental settings, including college
communities (Geller, Paterson, & Talbott, 1982; Rudd & Geller, 1985),
shopping malls (Elman & Killebrew, 1978), high schools (Campbell et
al., 1982), banks (Geller, Johnson, & Pelton, 1982; Johnson & Geller,
1984), and industries (e.g., Geller, 1983, 1984; Geller & Hahn, 1984;
Horne & Terry, 1983).
The success of these
settings (i.e., a doubling
intervention levels) has
incentive
of safety
prompted
programs across
belt usage from
the NHTSA to
such diverse
initial, pre-
promote the
implementation of communitywide incentive programs in six cities (i.e.,
Fresno, CA; Dover, NJ; Kalamazoo, Ml; San Antonio, TX;
Natchitoches, LA; and Suffolk County, NY). In each of these cities,
NHTSA sponsored a reward program whereby vehicles were approached
at intersections and passengers wearing safety belts were offered
rewards donated by community merchants ("U.S. is Trying Safety
10
'Bribes"', 1983). Similar community programs have been implemented in
Chapel Hill, NC (Campbell, Hunter, & Gemming, 1983), and
Jacksonville, MS (Long, 1983). Geller (1984) reviewed the outcomes of
28 incentive-based programs which have been successful at increasing
safety belt use in corporate and community settings. He concluded:
"this review clearly supports the beneficial impact of certain incentive
strategies for initiating the practice of safety belt use in a matter that
also fosters public acceptance and positive attitudes toward
transportation safety" (p. 16).
Limitations
Although the outcomes of the studies reviewed by Geller have been
encouraging, much of their large-scale applicability is limited because of
substantial promotional and labor costs and a substantive decline in
safety belt use after the incentives are withdrawn (Geller, 1984).
large-scale incentive programs target a dispersed population of
individuals emitting divergent behaviors. Thus, promotional effects are
difficult and costly, and must compete with numerous other
advertisement schemes and environmental cues (Geller, 1984). For
example, Campbell et al. (1983) estimated the cost of advertising to
promote their campaign and to recognize businesses that provided
incentives to be over ten thousand dollars.
To
Geller
overcome these shortcoming of
(1984) recommends that future
incentive-based programs,
efforts should become
"institutionalized" (i.e., a system that uses people in grass root
agencies and organizations to promote the continual operation of the
11
safety belt program). By taking advantage of indigenous personnel,
the costs of an incentive program may be drastically reduced and the
program may continue over the long term as standard practice.
Problems of short-lived and transitory effects may be ameliorated by
establishing a mechanism by which the community incentive program is
made integral part of normal community affairs (Geller, 1984).
To assess the practicability of these claims, Rudd & Geller (1985)
developed a university-wide program that engaged the campus police
department as a delivery agent. They reported that the program, by
employing indigenous campus police, represented a much smaller
investment than that expended in other community studies, yet yielded
comparable results. The campus police department is illustrative of one
type of community service agency that can be used to deliver incentive
programs.
hospital.
Another type of indigenous organization is a community
The use of a community hospital to deliver a safety belt
incentive program would add strength to the claim that indigenous
"grass root" agencies can effectively deliver a safety belt promotion
program.
A potential limitation of all inctentive strategies is called the
"overjustification" effect. The overjustification effect occurs when
unnecessary incentives are used to motivate an action that an individual
would have undertaken voluntarily (Grano & Sivacek, 1984). The
individuals behavior is under the control of external inducements,
rather than the individual's own personal commitment to the desired
behavior. Thus, when the external motivators are removed, the target
12
behavior often returns to baseline levels because an "internal
justification" for continuing the desired response was not developed.
To avoid this limitation, Lepper (1981) suggests the use of modest
rather than highly attractive external motivations for controlling
behavior. The present study incorporated the "minimal justification
principle" in the development and administration of an intervention to
promote safety belt use at a hospital setting.
Commitment Paradigm.
In the typical commitment paradigm, subjects are presented with an
opportunity to "commit" themselves to a specific action for an agreed
upon length of time. To the extent that the external pressure to make
the decision is minimal, the strength of a personal commitment can be
considerable ( Pardini & Katzev, 1983) and the person will feel
responsible for the action ( Kiesler, 1971). Conversely, if external
contingencies are used to encourage compliance with an act, they are
attributed as the cause of the behavior (c. f. Bern, 1967, 1972; c. f.
Kelly 1967, 1973), and long-term behavior change will not occur
(Lepper, 1983). Moreover, if the commitment motivators are perceived
as unnecessary incentives, the subsequent interest and activity can
diminish, as accounted for by the two-stage incentive-arousal
ambivalence hypothesis, which states that "the inducement of an activity
through the use of unnecessary extrinsic incentives stimulates an
ambivalent reaction on the part of the receiver" (Crano & Sivacek,
1984). According to this view, extrinsic reward does not result in an
decrement in motivation unless subsequent information (actual or
13
perceived) confirms the apprehension that produced the ambivalent
reaction. In other words, the actor must discover, invent, or be
provided with information that suggests potentially negative features of
the reward-induced actions (Crano & Sivacek, 1984).
Theoretical Commitment Perspectives
A number of definitions of commitment exist. For clarity of
discussion, Kiesler and Sakumara's (1966) definition of commitment as
the "pledging or binding of the individual to behavioral acts" (p.349)
was adopted herein. This behavioral orientation assumes that a
person's self view is partially dependent upon his interpretation of his
own behavior. As such, this approach is consistent with Hieder
(1958), Kelly (1967) and Bern (1967), in that they all discuss situations
where individuals make inferences about themselves on the basis of
their behavior. In Kiesler's (1971) words, "the person's view of
himself, his social identity, depends partly on his own behavior and his
interpretation of his own behavior" (p.43). The following two
paragraphs present a cursory synopsis of the commitment construct as
given in Kiesler's (1971) book, "The Psychology of Commitment".
Kiesler enumerated four preliminary assumptions about
commitment. First, individuals attempt to resolve inconsistencies
between the attitudes they hold and behavioral acts which they are
induced to perform. This assumption relates to the social psychological
theories of consistency (e.g., cognitive dissonance). The second
assumption is most critical. Specifically, the effect of commitment is to
make an act less changeable. In other words, the commitment to a
14
desired behavior (e.g., pledging to wear safety belts) is manifested in
terms of the person's resistance to change. That is, people committed
to an act are more resistant to change and therefore, committed
individuals should demonstrate longer response maintenance. A
corollary to this assumption is "that commitment also makes the cognition
representing the behavior more resistant to change as well" (p.31).
For committed individuals, both their behavior and their "thoughts" are
more resistant to change.
The third assumption pertains to the relationship between the
degree of commitment and the effects of commitment. Formally, the
magnitude of the effect of commitment should be positively and
monotonically related to the degree of commitment. One way to
operationalize the degree of commitment is in terms of time. That is, if
people are given a choice as to how long they would commit themselves
to a specific behavioral act, those people who choose to pledge for
longer durations should, on the average, wear their safety belts with
greater frequency and longer duration.
Finally, it is assumed that commitment can be increased by
manipulating one of more of the following five techniques:
1. The explicitness of the act (e.g., How public or otherwise
unambiguous was the act).
2. The importance of the act for the subject.
3. The degree of irrevocability of the act.
4. The number of acts performed by the subject.
5. The degree of volition (or freedom or choice) perceived by the
rs person when performing the act.
The mechanism(s) by which commitment influences an individual are
subject to several equally plausible interpretations. Commitment
mechanisms have been interpreted in the context of: (a) the goal
setting paradigm (i.e., Becker, 1978; Bachman & Katzev, 1982), (b)
the operant perspective (Geller, 1982; Horne & Terry, 1983), (c) the
"minimum justification principle" (Pardini & Katzev, 1983) which is
actually a derivative of two mega-social psychological theories, i.e.,
Bern's self-perception theory and Kelly's self-attribution theory
(Lepper, 1983), (d) a self-monitoring perspective (Pallack & Cummings,
1976), and (e) the low-ball procedure for producing compliance as
suggested by self-perception and dissonance theories ( Cialdini,
Cacioppo, Bassett, & Miller, 1978).
Although there is apparent disagreement over the exact
mechanism(s) by which commitment operates, there does appear to be
some consensus as to the outcome of commitment strategies. For
example, Pardini and Katzev (1983) claim that inducing people to make a
commitment acts as "a powerful catalyst for initiating and maintaining
recycling behavior" (p. 252). However, the degree of commitment is
moderated by one's perception that he or she was free to have acted
otherwise (Kiesler, 1971). This reasoning suggests that for commitment
to have an effect, the person has to choose the behavioral act without
the perception of external pressures or response contingencies. The
greater the extent to which an individual acts without external
contingencies, the more responsible the person should feel for his/her
16
behavior (Kiesler, 1971). In this context, an incentive may exhibit an
inverse relationship to commitment. That is, increasing the extrinsic
value of incentives may correspondingly reduce the impact of
commitment. Heider ( 1958) offers that one's perception of self-
responsibility is the very core of commitment.
Commitment in and of itself is not considered a motivating force.
As stated by Kies I er, ( 1971) :
Commitment doesn't compel us to do something; it is inert. However, because of its binding or freezing properties, it does influence our response to other forces or situations that do compel us to do something, e.g., to move somewhere or react in some way.
Thus, if a person's goal is to motivate another person to change a
behavior, for example, to get someone to wear his/her safety belt,
using commitment alone would not be sufficient (although for permanent
change it may be necessary).
It is at this juncture where the motivating properties of incentives
can be tied in with use of a commitment strategy. Specifically,
incentives could be used to motivate people to wear their safety belts,
and having done so, the effect of commitment would be to make the act
less changeable in the future. And therefore some response
maintenance should occur. This notion was applied in the design of the
interventlon evaluated in the present study.
The design of an incentive strategy has to be carefully
considered. One pitfall in the use of monetary incentives is that a
person induced to perform some behavior for a particular sum of money
is only committed to the behavior relative to some other level of
17
inducement ( Kiesler, 1971). For example, a mercenary induced to
perform an act for some amount of inducement, may decide not to
perform the act if offered a larger inducement. In other words, the
person may not develop internal justification for performing the desired
behavior. This suggests the target behavior is on an auction block,
with its direction subject to the highest bidder, i.e., strongest
inducement. A delicate balance appears to exist, where if the incentive
is too powerful, people will make external attributions for their present
behavior and will not maintain the behavior change, but if the incentive
is too weak, it may not motivate behavior change.
Survey of Applied Literature
Only within the last few years have commitment tactics been
applied to the amelioration of low safety belt usage. In most cases, the
commitment is obtained by having individuals voluntarily sign a "pledge"
card. It is noteworthy that in some of the first large-scale projects
that incorporated commitment techniques, the focus of the intervention
was actually on increasing safety belt use with incentives. That is,
because of implementation constraints, commitment through the signing
of pledge cards was used as a medium through which the incentive
program was administered. For example, at the General Motors
Technical Center the high volume of traffic prohibited the use of a
direct reward strategy. Instead, a commitment-based program was
implemented whereby employees were offered opportunity to sign a
pledge card and commit themselves to wearing their safety belts for one
year (Horne & Terry, 1983). The incentive was the opportunity to win
18
a new automobile, contingent upon both the signing of a pledge card
and the achievement of predetermined average safety belt usage levels
on the Tech Center grounds. The program demonstrated remarkable
success, as the level of safety belt usage increased from a baseline
level of 36% to a peak of 70%. Even more outstanding is that two years
after the removal of the safety belt program, usage levels remained at
approximately 6090 (Horne, 1984).
In a industry-based experiment (summarized in Geller & Bigelow,
1984), a pledge card commitment strategy was paired with awareness
sessions and was not accompanied by incentives. The intervention
demonstrated substantial increases in employee safety belt usage for the
pledge card signers. More specifically, the pledge card signers
doubled their belt wearing (from 17.2% to 33.7% mean usage) compared
to minimum increases by the non-signers.
The awareness session-pledge card intervention was evaluated in
two other industrial studies. Kello & Geller (1985) claimed significant
increases in safety belt use comparable to results of the best incentive
programs, using only awareness sessions and commitment opportunities.
Moreover, Cope, Grossnickle, and Geller (1985) obtained results
comparable to the Geller and Bigelow study.
Other programs have found that commitment alone is insufficient to
motivate safety belt use in applied settings. Talton (1984) implemented
a church-based pledge card program in which church-goers were
offered the opportunity to commit themselves to wearing their safety
belts for four weeks. The results of the program were not startling as
19
only 1090 of the 441 possible individuals signed a pledge card. And of
the 10% that did make the commitment, the pledge card signers had a
baseline usage rate of 65%, compared to 26% for non-signers. These
results suggest that it may be necessary to have a commitment program
that is supplemented by a strategy that can motivate the signing of
pledge cards. It is noteworthy that all of these studies of a
commitment intervention included relatively short-term evaluations.
Several of the studies mentioned above (e.g., Cope et al, 1985;
Geller & Bigelow, 1983; Kello & Geller, 1985), did not use incentives to
motivate pledge card signing. Rather, awareness sessions and small
group discussions were successful in securing a larger portion of the
participants to make a buckle-up commitment. When incentives or
awareness sessions were absent, most people did not sign pledge cards
(Talton, 1984).
20
Limitations
Commitment is allegedly an internally motivated and controlled'
construct, yet in research situations external pressure is often applied
e.g., by threatening to post participant names publicly ( Pal lack &
Cummings, 1976), by obtaining signatures of participants on multicopy
documents with the change agent possessing a copy of a person's
commitment (Pardini & Katzev, 1983), or by offering opportunities for
rewards (Horne & Terry, 1983; Geller & Bigelow, 1984). As discussed
above, to the extent that external contingencies induced the
commitment, the probability of an individual internalizing that
commitment and maintaining the committed behavior is reduced.
Compounding the issue, Talton's (1984) results indicate it may be
difficult to obtain commitment in the absence of external contingencies
or awareness/education sessions. The challenge, therefore is to
maintain the perception of freedom at the expense of imposing
contingencies to motivate the actual commitment.
In an attempt to resolve this paradox, Streff ( 1984) discussed a
plausible solution. Specifically, Streff suggests that an optimal mix of
incentive and commitment procedures be developed that will motivate the
act of commitment and maximize the number of internal attributions for
the commitment. The research of Horne & Terry (1983) suggests that
one way of obtaining commitment and maintaining significant, long-term
behavior change is to offer a large reward (i.e., a new car) with a low
probability of winning; however, it is not practical to expect the
frequent availability of a new car for use as an incentive. Clearly
21
there exists a need to develop strategies that will motivate people to
make internally-based· commitments and that can be implemented by
organizations which do not have access to expensive incentives. A
primary aim of this study was to explore this possibility.
Hypotheses
Based on the review of the theoretical and applied literature, the
following specific hypotheses were derived and tested.
1. Those people induced to make a commitment to wear a safety belt
who previously did not wear a safety belt will "act in consonance
with the pledge" and wear their safety belts.
2. Those people who signed a pledge card should continue to wear
their safety belt after the removal of the incentive condition.
3. The percentage of safety belt wearing across the intervention and
follow-up conditions should be higher for those people who pledged
for longer durations.
4. The baseline level of safety belt usage of the subjects that choose to
sign pledge cards should be higher than the non-signers.
5. A main effect for observation time should occur. During the
afternoon recording sessions more people will be exposed to the
data recorders immediately before the opportunity to buckle-up
than during the morning shift when more people are arriving at
the hospital. To the extent that the observers presence affects
safety belt usage, the afternoon shift should demonstrate higher
safety belt usage.
6. Non-signers of pledge cards should demonstrate some increase in
safety belt usage for a number of reasons, e.g., modeling,
salience, peer pressure.
22
Method
Subjects and Setting
The study was conducted at Radford Community Hospital (RCH) in
Radford, Virginia (pop. 13,325). At the commencement of the project,
520 people were employed (including administrative personnel, medical
staff and service employees) and approximately 200 volunteers were
working at RCH. The study targeted all drivers affiliated with RCH.
Initially, two locations were used as observation sites: one site
was located behind the hospital in front of the entrances to the main
parking lot, and the other site was located on a corner in front of the
hospital. However, because the front site had a small volume of traffic
(approximately 10 cars recorded per observation session), after the
third week of the intervention, only the back site was used.
Design
The study incorporated an A-8-A
(baseline/intervention/withdrawal) design that included a follow-up
evaluation four months after the completion of the withdrawal phase.
The paradigm included a long-term follow-up evaluation and thus
avoided the limitations of a short-term evaluation effort.
General Observation Procedure
The data were collected on four observation sessions a week, twice
in the morning and twice in the afternoon (except du ring baseline)
when three morning and three evening sessions occurred weekly. Each
week the days of the sessions were determined by a computer-generated
random program. The morning sessions were from 6:30 a.m. to 8:30
23
24
a.m. and the afternoon sessions were from 3:00 p.m. to 5:00 p.m.
These times coincided with shift changes, affecting a majority of the
hospital workers.
At the start of each data collection session, two observers: a)
completed the top section of the data sheet as indicated (see Appendix
A for a sample data sheet), b) stationed themselves approximately 20
feet apart, and c) recorded independently the license plate numbers of
all vehicles as they entered and exited the hospital parking lot. They
also recorded the following: whether the front seat occupants were
wearing shoulder safety belts, the gender of the front seat occupants,
and the availability of a shoulder belt. The data collectors attempted to
observe all the vehicles that entered or exited the parking lot.
Sometimes the observers walked around the parking lot if all the data
for a particular vehicle had not been recorded (e.g., the presence of a
buckle-up pledge card). The data collector who recorded the most
observations for a particular session was considered the main observer
and it was this data that was used for the analyses.
collected by the other observer was used for reliability checks.
Baseline
The data
The recording of baseline data occurred for two weeks and
included six sessions per week. Data were collected at both locations
by two independent observers at each location. The observers were
clearly visible to the hospital staff during this time period. If the
observers were questioned as to what they were doing, they were
instructed to respond simply that they were obtaining data on the use
25
of vehicle safety belts for a research project.
Intervention
The intervention period lasted six months and included awareness
sessions and a unique combination of an incentive program and
commitment strategy. The intervention efforts were coordinated
through the Human Relations Department of Radford Community
Hospital. In the planning stages this group obtained permission to
conduct the project, procured funds to finance the project, scheduled
awareness sessions, and publicized the campaign. They employed a
variety of promotional schemes to make the hospital affiliates aware of
\Yhat was termed "The Buckle-up for Bucks" campaign.
A special bulletin was prepared by the human relations staff and
distributed with the hospital's regular in-house publication. See
Appendix B for an example of this bulletin. Details of the program
were also included in a flier that accompanied the paid employees
paychecks. Finally, a 3' x 5' display case located in the main entry
hallway exhibited the project description and a thermometer showed the
number of people that had signed a pledge card. Throughout the six-
month intervention the human relations staff distributed and collected
pledge cards, handed out rewards to the winners, provided information
about the project to the hospital affiliates, and posted the weekly
winners names in the display case.
Field data during the intervention period was collected four
sessions a week for six months and followed the observation procedure
detailed above with three slight modifications. First, as previously
26
mentioned, after three weeks the front lot was no longer used for data
collection. Second, the field enumerators began to record whether
there was a pledge card displayed on the dashboard of the observed
vehicles. Several factors affected the visibility of the displayed pledge
card (e.g., lighting conditions, position of card, position of data
recorders) and therefore, the observers often had to exert extra effort
to determine the presence of a pledge card. And third, the
instructions to the observers regarding their responses to inquires from
the hospital staff were modified. They were instructed to respond by
first asking the person if they were familiar with the safety belt
"Buckle-Up for Bucks" campaign. If the inquisitor responded "yes",
the observer explained they were evaluating the effectiveness of that
program. If the person was not familiar with the program, the
observer briefly explained both the campaign and their role as
evaluators and directed them to the office of community relations.
Awareness Sessions. Du ring the first week of the intervention,
four 30-minute awareness sessions were conducted -- two were led by
Dr. E. Scott Geller and two were led by the author and another
graduate student ( Fredrick Streff). The awareness sessions were
offered on a volunteer basis for persons affiliated with the hospital
staff. Two weeks later, Mr. Streff and the author conducted two more
awareness sessions: one for the cooking staff and one for the
maintenance staff. Each of the awareness sessions was attended by 10
to 15 employees or roughly 10 percent of the total population.
At the beginning of every awareness session the discussants were
27
introduced to the attendants and it was explained to the participants
that the safety belt "Buckle-Up for Bucks" program was sponsored by
the hospital, directed by the Community Relations Office, and evaluated
by the Virginia Tech researchers.
All of the awareness sessions consisted of a 3-minute film and
20-30 minutes of presentation/discussion about the potential positive
benefits and negative side-effects of wearing safety belts. The film
entitled: "Egg, Pumpkin, Headache" (produced by the National
Highway Traffic Safety Administration) depicted three distinct scenes
that demonstrated the potential effects of being unrestrained during an
auto accident. Subsequent discussion focused on the theme of the film
which was: "What's holding you back from wearing your safety belt?"
Examples of questions that were posed to prompt discussion included
the following: (a) How many of you wear your safety belt?, (b) For
those of you who do not wear your safety belt, what is holding you
back?, (c) How many· of you have been in a serious accident or know
someone who has?, (d) How many of you believe safety belts do not
help in a vehicle crash? Why?
Incentive Program and Commitment Strategy.
Each week du ring the six-month intervention phase (at a time and
day randomly selected by a computer program), a five dollar cash
certificate was awarded and every sixth week a twenty-five dollar cash
certificate (both redeemable at the Community Relations Office) was
given to the driver of the first car that met the commitment
contingencies (detailed below). If none of the vehicles observed du ring
28
the designated observation session satisfied the requirements, the cash
certificate was awarded to the first driver who fulfilled the commitment
contingencies at the next observation session.
To be eligible for the cash prizes the hospital affiliates had to
meet the following contingencies which were specified in paycheck
inserts, posters, and newsletters: (a) they had to be observed wearing
their safety belt, (b) they had to make a written commitment to wear
their safety belt by signing a pledge card, an example of which is
depicted in Appendix 3, (c) the pledge card had to be displayed on the
dashboard of their vehicle, and (d) they had to pledge for a duration
that ensured eligibility at the time (i.e., if people only pledged to wear
their safety belt for one week, they would be eligible to win a prize for
that week; if they pledged for a month they would be eligible for that
month and so on).
After a person signed a pledge card, the stub was returned to the
Community Relations Office. On the ticket stub an entrant wrote
his/her name, phone number, auto license number, and piedge
duration. An individual had the option of pledging for one week, one
month, three months, or six months. If they choose a duration other
than six months they were encouraged sign another card at the
Community Relations Office. Originally an attempt was made to color
code the pledge cards to assess possible differential effects of the
program on the different hospital subgroups (e.g., doctors, nurses,
service staff, volunteers); however, because of problems encountered
with pledge card administration and with viewing the different colors
29
through a vehicle windshield, an accurate assessment was impossible.
Therefore all pledge card signers were analyzed as a single group.
Withdrawal
The withdrawal period began the week after Thanksgiving, ten
days after the completion of the intervention phase. Observers
continued to record observations of safety belt use as described du ring
the baseline and intervention periods for two consecutive weeks. No
attempt was made to record the presence of pledge cards du ring this
period.
Follow-Up
Field enumerators began collecting follow-up data four months after
the completion of the withdrawal period. Follow-up field observations
were recorded for three consecutive weeks using the same procedures
described above in the baseline and intervention phases.
Results
I nterobserver Reliability
Two data collectors, collectively, recorded information from 23, 185
vehicles. From this total, 435 observations (approximately 290) were
deleted because the observed vehicle did not have a shoulder belt.
Observer 1 recorded 15,326 vehicles and Observer 2 provided the
reliability data for the subsequent analysis with 7,427 observations
(48.5%). As noted above, for each observation the observers recorded
whether a shoulder belt was available and worn by front-seat occupants
and the gender of both drivers and front-seat passengers. During the
intervention phase, they also recorded the presence or absence of a
pledge card on the vehicle dashboard. I nterobserver agreement was
calculated by dividing the total number of observations in agreement for
a particular data category by the total number of agreements and
disagreements and then multiplying by 100.
The results of the reliability analysis are presented in Table 1.
Observations from the following five data categories were used in the
calculation of the ten reported reliabilities: 1) the safety belt usage of
the drivers, including both the number buckled up and the number not
buckled up, 2) the gender of the drivers, including the number of
agreements for both males and females, 3) the shoulder belt usage of
the passengers, both wearing and not wearing, 4) the gender of the
front-seat passengers, for both females and males, and 5) the display
of pledge cards, including agreement for presence and absence of
pledge cards. An examination of Table 1 reveals that interobserver
30
31
Table 1
Results from the Interobserver Reliabililty Analysis Including Frequencies and Percent Agreements
Frequencies of Observations ------------------------------------
Number of Category Observer 1 Observer 2 Agreements
Percent Agreements
-------------------------------------------------------------------------Driver Belt Usage
Wearing 4715 2685 2523 94.0
Not Wearing 10610 4739 4591 96.9
Driver Sex
Males 3157 1469 1291 87.8
Females 12168 5956 5808 97.5
Plege Cards
Pledge 1521 913 813 89.1
No Pledge 13805 6514 6429 98.7
Passenger Belt Usage
Wearing 1216 686 813 90.2
Not Wearing 2917 1352 1299 96.l
Passenger Sex
Males 867 442 383 86.7
Females 3266 1712 1591 92.9
32
agreement for all ten reliabilities ranged from a low of 86.3 9a to a high
of 98. 7%. It is noteworthy that in every instance of a dichotomous
response category (e.g., male vs. female or wearing vs. not wearing),
the categories which were observed less frequently were also less
reliable. This observation supports the argument that it is important to
calculate observer reliabilities for each instance of a operationalized data
category (c. f. Geller & Rudd, 1985).
Description of Shoulder Belt Usage
The percentage of shoulder belt usage for the entire sample, as a
function of experimental condition, is displayed in Figure 1. For the
baseline, withdrawal, and follow-up conditions data were collected for
two weeks. The intervention phase data were collected for six months.
The 6 baseline data points represent the mean daily shoulder belt usage
and consist · of both the morning and afternoon observation sessions.
All of the 24 intervention phase data points reflect the mean of five
consecutive sessions (with the exception of the last intervention phase
data point, which included four sessions). The 8 withdrawal and 11
follow-up data points represent mean daily usage and therefore consist
of one or two observation sessions. Each data point of the intervention
phase in Figure 1 represents a mean of 360 observations (range = 217
to 630). The data points for the baseline, withdrawal, and follow-up
phases represent a mean of 72 observations each ( range = 24 to 143),
with all 49 data points representing a total of 15,326 observations.
A visual examination of the mean levels of safety belt wearing by
phase suggests that the intervention was successful. Percentage of
33
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34
shoulder belt wearing increased from a baseline mean of 15.6% to an
average of 34. 7% during "'intervention, and subsequently decreased to a
withdrawal level of 25.6%. Interestingly, the follow-up phase
documented a slight increase in the level of safety belt wearing with a
mean of 28. 6%.
Whereas Figure 1 depicts the safety belt usage of the entire
sample, Figure 2 presents the the percentage of safety belt usage for
pledge card signers and non-signers within each condition. In other
words, the total sample was bifurcated into subsamples, a group of
pledge card signers and a group of non-signers. Mean percentages of
safety belt wearing for each group by experimental condition are also
shown. The mean number of observations per data point was 22
(ranging from 8 to 48) for the pledge card signers, and 55 ( ranging
from 23 to 98) for the non-signers.
The difference between safety belt usage levels for the pledge
card groups is striking. For the pledge card signers, mean of safety
belt use increased from 29.4% 'in Baseline to 75.1% during intervention
to 56.0% and 44.9% for the withdrawal, and follow-up phases
respectively. In contrast, the usage means for the non-pledge card
group changed from 11.8% to 17.7% to 17.1% to 22.1% for the same
phases.
A summary of safety belt usage and number of observations for
the three groups (i.e., overall, pledge signers, and non-signers)
within each of the four experimental phases is shown in Table 2. Also
included in Table 2 are the number of different vehicles observed (i.e.,
35
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36
Table 2
Means and Frequency of Observations for Pledge Card Signers, Non Pledge Card Signers, and Overall
as a Function of Experimental Condition
Experimental Condition
Baseline
Mean Total N
Vehicles
Intervention
Mean Total N
Vehicles
Withdrawal
Mean Total N
Vehicles
Follow-Up
Mean Total N
Vehicles
Means and Frequencies of Observations
Pledge Card Signers
29.4% 161
(n=56)
75.1% 3740
(n=l88)
56.0% 220
{n=77)
44.9% 231
(n=69)
Non Pledge Card Signers
11.8% 1378
(n=873)
17.7% 7549
(n=2740)
17.2% 886
(n=496)
22.1% 1032
(n=587)
Overall
15.6% 1539
(n=929)
34. 7% 11289
(n=2928)
25.6% 1106
(n=573)
28.6% 1263
(n=656)
Note: Vehicle is the number of different license plates recorded
37
subtotals) within each of the twelve cells (three groups X four phases).
For example, in the baseline condition 161 total observations were made
of vehicle occupants who eventually signed pledge cards. Because
there were repeated observations across time, only 56 different license
plates were recorded. Similarly, 7,549 observations were recorded
during the intervention phase for the non-pledge group, but this result
included only 2,740 different license plates. Examination of Table 2
also reveals the number of people who signed pledge cards. A total of
188 different license plates were recorded for the pledge card signers
during the intervention phase. Out of a possible 720, 188 or 26.1%
made a commitment to wear their safety belts.
Interrupted Time Series Analysis
As the above paragraph notes, repeated observations of individuals
safety belt wearing behavior occurred across time. This data structure
is referred to generically as time series because there is one data point
for each point in time. The design is specifically an interrupted time
series because there are clear temporal distinctions at each of the
phases (Judd & Kenny, 1981). There are unique problems to this type
of data structure. In particular, "When naturally occurring events or
behavior are observed repeatedly over time. . . events closer to each
other in time tend to be more correlated with each other than with
events further removed in time" (Cook & Campbell, 1979, p. 234). The
dependency between adjacent observations is called serial dependency.
Statistical independence, a critical assumption for analysis of variance
and the broader regression analyses, occurs when knowledge of the
38
occurrence of one event gives no information concerning the outcome of
the second, or vice versa. To the extent that the data exhibit serial
dependency, the estimates of the standard deviations (and hence, of
significance tests) are biased (Cook & Campbell, 1979). Therefore, if
there is serial dependency in the data, the researcher must adjust out
that dependency. Failure to do so biases tests of significance for the
treatment effects.
One general measure of serial dependency is called autocorrelation.
Autocorrelation describes the structural dependency among adjacent
observations and is computed on the residuals, not the raw
observations. Autocorrelation is similar to the Pearson product-moment
correlation for it indicates the degree of relationship between the
residuals of a current observation and the residuals of N-1 lags (See
Judd & Kenny, 1981, for computational details).
To check for autocorrelation, Box and Jenkins (1976) recommend a
chi-square test for white noise, i.e., randomness of the residuals.
Three tests were conducted, one on each of the data sets (i.e.,
overall, pledge signers, and non-signers). Before the autocorrelation
analysis, the data sets were transformed to difference scores by
subtracting the mean percentage of safety belt use for each observation
from the mean level of safety belt use for the corresponding phase
(Fouts, 1985). The results of the autocorrelation analyses for each of
the three data sets yielded mixed findings. For the pledge card group
and overall, the data exhibited serial dependency with chi-square
values of (6, N=l 51) = 136. 5, p < . 0001, and (6, N=l 51) = 40. 1, p <
39
.0001, respectively. The data, however, for the non-pledge group
were not autocorrelated giving a chi-square of (6, 151) = 2.47, p =
.87.
When data are autocorrelated (i.e., serially dependent), it is
suggested that interrupted time-series analysts use the autoregressive
integrated moving average (ARIMA) models (Cook & Campbell, 1979) and
the associated modeling techniques developed by Box and Jenkins
(1976). These techniques provide for unbiased estimates of the error
in a series. Typically this is· done in a series of three steps: model
identification, parameter estimation, and diagnosis. In the identification
phase, the analyst attempts to identify a model that accurately
describes the systematic component of the residuals. The
autocorrelation function (ACF) and the partial autocorrelation function
(PACF) are used for this purpose. Once the model has been identified,
the model parameters are estimated with nonlinear softwear. The ACF
and PACF for the residuals of this model are then used to diagnose the
adequacy of the model. If diagnosis indicates that the model is
inadequate, a new ARIMA model must be identified; its parameters
estimated; and its residuals diagnosed. This process is repeated until
an adequate ARIMA model is generated. The following presentation of
results was guided by personal consultation with a time series specialist
at Virginia Tech (Fouts, 1985) and by adhering to guidelines for
analyzing an interrupted time-series data set (McCain & McCleary, 1979;
Judd & Kenny, 1981).
Identification. For any given time series, the first hurdle is to
40
identify the systematic part of the stochastic component (i.e.,
residuals) of a time series so that it can be described by an ARIMA
model. There are two classical models: autoregressive and moving-
average. As Judd and Kenny (1981) state, "These are two different
'strains' of the 'disease' serial dependency" (p.141). The moving-
average model was not pertinent in this analysis. Consequently, only
the autoregressive model is discussed in the following presentation of
the time series results. (For a discussion of the moving average model
see McCain & McCleary, 1979; Judd & Kenny, 1981).
The model is called autoregressive because each error is regressed
on a previous value of itself. The obtained value is the autocorrelation
between one observation and its preceding observation. Two types of
autoregressive models are considered: a first-order and a second-order.
For the first-order autoregressive model, each error or residual is
assumed to be a function of only the previous error or residual. In
addition to the autocorrelation between an observation and its preceding
observation, a first-order autoregressive process also predicts the lag
correlations of an observation for the second through the 30th previous
observations. Two criteria indicate a first-order autoregressive model:
the autocorrelation functions (ACF) dampen off at a deaccelerating rate
and the partial autocorrelation functions (PACF) of lag two or greater
are zero.
A second-order, autoregressive model also exhibits an ACF series
that dies off rapidly. Unlike the first-order model, however, the
second-order has: (a) the current observation caused by the two
41
previous values, and (b) the PACF's of lag three or greater are zero.
The PACF's are especially diagnostic of the order of the autoregressive
process; because, all PACF's greater than the order of the process
should be zero (Judd & Kenny, 1981). In other words, the number of
PACF's greater than zero is equivalent to the order of the
autoregressive process.
Every stochastic process has a distinctive ACF and PACF. The
interpretation of these distinct signatures is called identification
(McCain & McCleary, 1979). The ACF is simply the correlation between
the time series and its lags. The PACF is closely related in meaning to
the ACF, but is calculated by a different formula. (See Box & Jenkins,
1976, p.64).
The ACF and PACF were calculated for each of the three data sets
(i.e., overall, pledge signers, and non-signers). Visual inspection of
the correlograms (graphs or plots of the ACF's and PACF's) suggested
two tentative ARIMA models: an ARIMA (2,0,0) model for the Pledge
group and an ARIMA (1,0,0) model for the overall sample. To provide
consistency in the analyses, the Non-pledge group was also analyzed
with the ARIMA procedure. The ACF and PACF functions for this
group approached an ARIMA (1,0,0) model. Thus, the first model had
two autoregressive parameters, whereas the second and third models
each had one. Loosely speaking, the autoregressive parameters can be
considered analogous to correlation coefficients. When the ACF function
dies out slowly and the PACF has two significant spikes, an ARIMA
(2,0,0) model is indicated and when the PACF has one significant spike
42
the model is an ARIMA (1,0,0).
Estimation. After the tentative ARIMA models of serial dependency
were identified, the next step was to begin estimating treatment effects.
To review, the ordinary multiple regression procedure cannot be used
to estimate the treatment effects because of the problem of serial
dependency. However, once the model of serial dependency is
identified, the outcome and predictor variables are transformed to make
the error structure uncorrelated, the effects of the treatment are
estimated by multiple regression, and the residuals of the transformed
outcome variable are computed.
For the Pledge group, six parameter estimates were generated, two
for the autoregressive elements and one for each of the four
experimental conditions. Five parameter estimates were produced for
the Non-pledge group and the overall sample, one for the
autoregressive component and four for the experimental conditions.
Statist_ically reliable effects were detected for all of the parameter
estimates except the autoregressive parameter of the Non-pledge group.
The absence of a significant effect is consistent with the results from
the autocorrelation analysis. Table 3 presents the results from this
estimation procedure. Depicted are the estimates for the autoregressive
parameters (analogous to correlation coefficients), mean estimates for
each of the experimental conditions, the standard error of estimate for
all values and their corresponding T-Ratios. The parameter estimates
are satisfactory in that they meet the criterion of statistical significance
(except for the autoregressive parameter of the Non-pledge group).
Group
Overall
Pledge
Non-pledge
43
Table 3
Results From the Estimation Procedure of a Time Series Analysis for Pledge Card Signers,
Non-pledge Card Signers, and Overall
Parameter
Autoreg,l
Baseline Intervention
Withdrawal Follow-up
Autoreg,l Autoreg,2
Baseline Intervention
Withdrawal Follow-up
Autoreg,1
Baseline Intervention
Withdrawal Follow-up
~RIMA: Least Squares Estimation
Estimate
0.45
17.31 34.42 25.96 29.01
0.53 0. 43
40.85 72. 45 54.79 43.01
0.08
11. 81 17.74 17.24 21. 79
Standard Error
0.07
3.09 1.09 3.48 3.08
0.07 0.07
9.59 10.21 11.58 12.81
0.08
1. 95 0.62 2.24 1.88
* Not significant
T Ratio
6.13
5.60 31. 59
7.46 9.43
6.99 5.78
4.26 7.10 4. 73 3.36
1.03
6.05 28.26
7.67 11.59
*
44
Diagnosis. After the parameters of a tentative ARIMA model have
been estimated and statistically significant parameter estimates have
been made, the model of the noise structure is complete (McCain &
McCleary, 1979). However, as mentioned above, the purpose of the
identification stage is to develop an ARIMA model that will describe the
systematic component of the error and will leave only uncorrelated error
unaccounted for by the model. The purpose of the diagnosis stage of
the analysis is to check whether the residuals from the model that were
computed from the transformed outcome variable behave as white noise.
If they do, the error modeling phase is halted and the time series
analysis is complete. If not, the model is inadequate and a new model
must be identified. For the model to be adequate, the ACF and PACF
of the residuals must meet two basic criteria. First, the ACF and
PACF correlograms should have no significant spikes at any of the lags,·
and second, the chi-square test for the ACF should not be significant.
Table 4 presents the results of the autocorrelation checks for white
noise for each of the data sets. An examination of Table 4 reveals that
the residuals for each data set at all lags were not significant. Visual
inspection of the correlograms indicated that there were no significant
spikes at any of the lags in the ACF's and PACF's for the three data
sets. Examination of the residuals revealed that each of the models met
the criteria for an adequate model, and therefore, the time series
analysis is complete.
Interpretation of the Time Series Results
As noted above, the T-ratios for all the parameters were
45
Table 4
Results From The Diagnostic Procedure of a Time Series Analysis for Pledge Card Signers, Non-pledge Card Signers, and Overall
Group
overall
Pledge
Non-pledge
Autocorrelation Check of Residuals ----~-------------------------------------To Lag
6 12 18 24 30
6 12 18 24 30
6 12 18 24 30
Chi Square
1.13 5.56
11. 81 16.98 22. 71
4.33 8.05
15.18 21.44 27.00
0.58 8.22
15.79 21.66 30.01
DF PROB
5 0.95 11 0.90 17 0.81 23 0.81 29 0.79
4 0.36 10 0.62 16 0.51 22 0.49 28 0,52
5 0.98 11 0.69 17 0.54 23 0.54 29 0.41
46
significant. However, these significant tests compare the magnitude of
each estimate to zero. This indicates nothing about differences in
safety belt usage within the phases for each group, nor anything about
differences in usage levels between groups for each individual phase
(i.e., pledge vs. non-pledge).
One method for examining the within and between group
differences in mean estimates of safety belt usage is to inspect the
means and confidence intervals for each phase of each data set. If the
confidence intervals (derived by adding and subtracting two standard
errors from the mean of each estimate) overlap, than the means are not
significantly different from each other (Fouts, 1985). Figure 3 depicts
the results from all three data sets and includes the means and
confidence intervals for each phase of each data set. As mentioned
above, the effects of the intervention can be assessed by examining the
confidence intervals around the mean estimates for the experimental
conditions within each group and among all three groups. If the
confidence intervals do not overlap, than the difference is significant.
It is noteworthy that this procedure for assessing significance is very
conservative. To be significant, any two phases have to differ by more
than four standard errors (two standard errors above one mean and two
standard errors below the other mean), which is two more standard
errors than the standard t-test.
Comparison of the confidence intervals among the overall data set
revealed one significance difference. The intervention phase was
significantly higher than the baseline condition. There was a slight
47
_ 100 <(
a:: <( --Q) en
70 '"-Q)
"'C
::::s 60 0 .c en 50
O"I C 40 '"-0
t Q)
30
f I f f - 20 C Q) u '"- t Q) 10 a..
B I W F 8 I W F 8 I W F
Overa 11 Non-Pledged Pledged FIGURE 3
MEANS AND CONFIDENCE INTERVALS OF THE TIME SERIES ANALYSIS FOR PLEDGE CARD SIGNERS, NON-PLEDGE CARD SIGNERS, AND OVERALL
48
overlap between the baseline and the follow-up conditions. Given a less
conservative assessment procedure, this difference would have also been
significant.
A startling result is the lack of any significant difference among
the phases in the Pledge group. An observational explanation for this
result suggests two reasons. The ARIMA procedure produced more
moderate means than the raw mean estimates. Specifically, the range
between the safety belt usage levels for the baseline and intervention
phases were reduced from 45. 7 to 31. 6. Also, the standard errors
were large for each of the phases. This means there was much
variability in the percentage of safety belt use per observational session
among the pledge card signers. In the non-pledge card signer group
there were two significant differences. The intervention and the
follow-up phases both had significantly higher safety belt usage levels
than the baseline phase.
Analysis of differences in usage levels between groups can also be
made by comparing the confidence intervals for the four experimental
conditions. Two significant results are indicated. First, the baseline
level of safety belt usage of the Pledge group was significantly higher
the baseline level of the Non-signers. Second, the Pledge group's mean
intervention and withdrawal levels were are significantly higher than all
the phases for the non-signers.
Analysis of Variance
To demonstrate the importance of checking for autocorrelation in time
series data, the data were reanalyzed with the traditional analysis of
49
variance (ANOVA) procedures. To the extent that the data are
autocorrelated, the significance tests for the ANOVA's will be biased.
Subsequently, incorrect conclusions about the effects of the
intervention would be made.
A 4 (Condition: Baseline vs. Intervention vs. Withdrawal vs.
Follow-up) x 2 (Time: Morning vs. Afternoon) x 2 (Card: Signed vs.
Non-signed) x 2 (Gender: Males vs. Females) ANOVA was performed on
the overall data set to assess the statistical significance of the
intervention on the recorded level of safety belt usage. Main effects
were detected for Condition, F (3,147)=16.42 p < .001, Card, F (1,
149)=219.81 p <.0001, and Gender, F (1, 149)=21.42 p <.0001. A
significant interaction was found for Card X Experimental condition, F
( 1, 149)=6. 94 p <. 0002, indicating that pledge signers were more Ii kely
to buckle up as a function of intervention than non-signers. No other
interaction was significant (p's > .10). A comparison of means for
males and females showed that males had a higher rate of safety belt
usage than females, 31.3 90 and 26.3% respectively.
Tukey's honestly significant differences (HSD) post hoc t-tests
were performed to determine what significant differences existed
between experimental conditions. All the comparisons between phases
were significantly different (p < .05) except for Baseline vs. Follow-up
and Intervention vs. Withdrawal. What this analysis indicates is that
the intervention had a significant effect and that this effect was
sustained throughout the withdrawal phase. The absence of a
significant effect for the Baseline vs. Follow-up comparison suggests
50
that the effect of the intervention was not maintained four months after
the cessation of the intervention.
Because pledge card signing interacted with experimental phase,
the differences in levels of safety belt use between experimental phases
for each group were assessed with Tu key's (HSD) t-tests. For the
pledge card signers, all pairwise comparisons were significant at the .05
level except between the Follow-up and Baseline conditions. For the
non-signers one comparison was significant, Baseline vs. Follow-up.
This result indicates that several factors (e.g., increased public
awareness and generalization across signers to non-signers etc.)
besides the intervention may have contributed to the observed increases
in safety belt use du ring Follow-up ..
In comparison to the analysis of variance procedure, the time
series analysis (after removing the autocorrelation in the data), found
many less significant relationships, both between and among the phases
of the different groups. For example, the 4 x 2 x 2 x 2 A NOVA
detected several significant differences including: Baseline vs.
Intervention, Baseline vs. Withdrawal, Intervention vs. Follow-up, and
Withdrawal vs. Follow-up. The time series analysis for the overall data
set revealed only one significant difference, Baseline vs. Intervention.
For the pledge signers, all pairwise comparisons using Tukey's HSD
were significant; in marked contrast, none of the pairwise comparisons
from the time series were statistically different (except Baseline vs.
Follow-up). However, the differences in mean daily safety belt usage
were still substantial between the baseline and intervention conditions,
51
i.e., 40.85 vs. 72.45, but by the two standard error confidence
criterion they were not statistically reliable. The post hoc Tukey test
for the non-signers found a significant difference between the Baseline
vs. Follow-up condition. Whereas the time series detected a significant
difference between both the Baseline vs. Intervention and Baseline vs.
Follow-up.
As discussed above, when error terms are correlated the
significance tests are biased. The comparison of the A NOVA and time
series revealed that many of the significant differences detected by the
ANOVA were unwarranted. When the autocorrelation was removed and
unbiased significance test criteria are used, much less significance was
detected.
Discussion
The research project demonstrated the efficacy of combining pledge
cards and incentives to increase safety belt use among the staff of a
community hospital. The intervention program was practical because it
was implemented by indigenous personnel. Like Rudd and Geller
(1985), who demonstrated that campus police can administer a safety
belt program, the present research showed that a community relations
department of a hospital can deliver a cost-effective safety belt
program. Overall, the safety belt usage during the six-month
intervention phase more than doubled the initial Baseline level, i.e.,
from 15. 6% to 34. 790. The cost of program administration was
approximately $350.00 (including all supporting materials and cash
incentives). Thus, each percentage point gain in usage translates into
an expenditure of $18.32. This figure represents an upper bound
estimate in that the overall sample contained a number of cars that were
not part of the intervention project. The total number of different cars
observed during the project was 2,928. Even allowing for a high
turnover rate, this figure is substantially higher than 720, the total
number of people affiliated with the hospital. If the baseline and
intervention means of 29.4% and 75. l9o for the pledge group are used in
the calculation, the cost per one percent increase in safety belt usage
is $7. 65. The pledge group sample includes only hospital affiliates and
is a more appropriate measure of cost-effectiveness. However, it is
noted that both these estimates are low. The cost-effectivness
calculations did not include the costs associated with organizing and
52
53
planning the project or with adminsitering the awareness sessions.
The results of the program may be interpreted from three
analytical perspectives: a) strict behavioral, b) traditional experimental,
and c) classic statistical. The discussion first addresses general
theoretical issues interpretable from and consistent with all frameworks.
Then, the separate perspectives are considered in light of their
findings and differences in conclusions are considered. Finally,
suggestions for future research are offered.
General Theoretical Issues
Awareness of the program and general public knowledge may have
been responsible for a slight increase in safety belt usage, but the
potential impact of an awareness session was drastically reduced because
less than 10% of the hospital population actually attended the awareness
sessions. This highlights a problem that researchers encounter when
conducting applied research lack of ·control in manipulating
experimental conditions. In the community hospital most of the workers
could not leave their duties to attend an awareness session. Even
though the hospital administrative staff supported the project, they
could not mandate attendance. With 90% of the population absent from
the manipulation, even if the impact of the awareness sessions was
substantial, the effects would not have been easily detected.
Therefore, the remaining discussion considers only the effects of the
incentive and commitment strategies.
One hypothesis that was not tested was the question of whether
those people who pledged to wear their safety belts for longer durations
54
indicated a greater degree of commitment, operationalized in terms of
greater safety belt usage levels and longer response maintenance.
Unfortunately, all the pledge card stubs (which contained the duration
of pledge information) collected at the Community Relations Department
were inadvertently thrown out by a member of the hospital cleaning
staff.
The commitment strategy was an attempt to intrinsically motivate
safety belt wearing by taking advantage of four of the five techniques
for increasing commitment detailed by Kiesler (1971). Specifically, the
following techniques were used:
1. The act of committing oneself was made explicit and public
by having the pledge card signers display the pledge card
on their dashboard (Geller & Rudd, 1985 report an
improvement in the method of displaying pledge cards)
2. Although the people made only one pledge, the behavioral
act of buckling up was performed several times du ring the
six-month intervention.
3. Powerful inducements were not used to motivate people to
sign pledge cards only information and a token
opportunity to win a small prize.
4. Subjects displayed the pledge card on their vehicle
dashboards, thereby providing a cue that should heighten
the availability of the safety belt commitment and thus
influence later overt behavior (cf. Halverson & Pallack,
1978; Pallack, Cook, & Sullivan, 1980). Thus, the pledge
55
card display had an influence through two independent
mechanisms. It made the commitment public so that other
people were aware and it served as a personal reminder or
cue for the pledge signers each time they entered their
cars. In addition to the above, the pledge signers could
control the only public contingency by choosing whether or
not to display their pledge on their dashboards.
The results ' suggest that the combination commitment/incentive
intervention was successful at motivating people to wear their safety
belts. The design of the study did not allow for a separate analysis of
incentive versus commitment strategies. The study evaluated an
intervention package which attempted to combine both approaches
optimally. Previous research has demonstrated that "the presentation of
reinforcers for behaviors previously occurring without external
reinforcement can decrease subsequent interest in and performance of
such behavior" (Hazer, Aeschleman, & Robertson, 1985, p.87). In
such situations, the individual attributes the cause of behavior to an
external contingency and reevaluates the behavior as less interesting
(e.g., Bern's self-perception theory & Kelly's self-attribution theory
and, more recently, the "overjustification effect"). Consequently, when
the external reward is removed a decrement in performance is obtained
(cf. Deci, 1975; Deci & Ryan, 1980; Hazer, Aeschleman, & Robertson,
1985).
The monetary incentive was not a salient, powerful, and
overwhelming motivator. Rather, the incentive scheme provided an
56
opportunity for participants to win a five dollar prize once a week.
Given that as many as 720 people could be eligible to win each week, a
one in seven hundred and twenty chance of winning a five dollar prize
is probably not a powerful extrinsic motivator for most people.
A number of theoretical formulations and empirical investigations
suggests mild or moderate incentives will facilitate internal attributions
by not providing sufficient extrinsic motivation to allow people to make
external attributions for their behavior (e.g., Berns' s self-perception
theory, and Kelly's self-attribution theory). For example, the "minimal
justification principle" (Lepper, 1981), emphasizes the use of modest
rather than highly attractive external justifications in controlling
behavior, especially when response maintenance and generalization are
desired. One result of behaviorally-based commitment interventions that
has received substantial empirical support is maintenance of responding
after the intervention is withdrawn.
Several applied studies in the commitment literature have reported
that committed individuals adopt behaviors that last longer than the
commitment itself; for example, promoting longer household energy
conservation behaviors (Pallack, Cook, & Sullivan, 1980); increasing
public bus ridership (Bachman & Katzev, 1982); and participating in
newspaper recycling projects ( Pardini & Katzev, 1984). Results from
studies where commitment was used to promote energy-related behaviors
led Stern and Aronson (1984) to suggest that once people believe that
they are publicly committed to saving energy, they adopt behaviors that
can last much longer than the public commitment itself. The results of
57
the present study provide partial support for this statement. That is,
more pledge signers wore their safety belts four months after the
removal of the intervention than at Baseline. However, several
participants did stop buckling up at the end of the pledge period.
A number of post hoc explanations may be postulated to account
for both the observed maintained increase and the prototypical decrease
in the percentage of safety belt wearing during Follow-up. First
consider the decrease. One explanation is that historical and
maturation effects produced a subset which was not representative of
the total sample. The number of different people observed du ring the
Follow-up was considerably less for both groups. For example, of the
188 people who signed pledge cards, only 69 or 36% were observed
during the follow-up phase. Thus, it is possible that the lower follow-
up level of safety belt usage is merely a artifact. In other words, if
the 119 people that were not observed had higher usage rates than the
69 observed people, the result is biased. Unfortunately, this
explanation cannot be supported with the available evidence.
An attributional explanation is that in spite of efforts to make the
incentives appear mild, people may have perceived them as powerful,
and attributed the cause of their behavior to the effects of the
incentives. The intervention was developed to minimize external
inducements and maximize the internal justification for wearing safety
belts. However, by focusing on the amount of prize money rather than
the relatively low probability of winning, many people may have
perceived the reward opportunity to be a powerful extrinsic motivator.
58
A total of two hundred and seventy-five dollars was given to the 20
hospital affiliate "Buckle-up for Bucks" winners. Throughout the six-
month intervention, an average of 0.38 cents per person was expended
to motivate safety belt wearing. Although the perceptions of hospital
affiliates should have been surveyed, realistically, it would not be
expected that .38 cents would motivate many people to wear their safety
belts for six months.
A final explanation is that the commitment component of the
intervention was not successful in developing the intrinsic motivation
necessary for producing long-term maintenance of safety belt wearing.
The public commitment to wear a safety belt for the six-month
intervention was successful in obtaining 7590 safety belt usage for six
months; yet the frequently encountered decline in performance after the
removal of the intervention was observed, suggesting that not all
subjects developed the intrinsic motivation important for maintenance of
belt wearing.
There are many possibilities when speculating as to why the
commitment/incentive intervention should have a long-term maintenance
effect. One suggestion is that commitment permanently weakened the
influence of those factors which previously kept people from performing
the behavior (cf. Bachman & Katzev, 1982). For example, people may
know how to conserve energy, but they do not perform the required
behaviors. However, once people begin to conserve energy by
performing conservation-related behaviors, the inertia (resistance to
change?) is overcome and the energy conservative behaviors are
59
maintained.
A second possibility is that commitment serves as an anchor by
which subsequent information is filtered ( Pallack, Cook, & Sullivan,
1980). What these authors and others suggest (cf. Halverson &
Pallack, 1978) is that commitment provides a framework that makes one's
attitude a guide for behavior in subsequent situations. In other words,
commitment may actually serve as a link between an attitude held in
previous situations and to behavior in other situations ( Pallack, et al.,
1980). By this line of reasoning commitment facilitates long-term
behavior change by directing the interpretation of subsequent behavior
in light of the previous act of commitment. For example, when faced
with a behavior choice people may consider past situations that are
similar and let their perceptions of the outcomes from these situations
guide their present actions.
Another possibility is suggested from the attribution literature.
People may not have perceived the incentives as being extrinsic
motivators. Rather, the incentives may have had the intended effect of
motivating people to sign a pledge card, and the effect of signing that
pledge care, i.e., making the commitment, was manifested in long-term
maintenance of safety belt wearing. In other words, some of the pledge
card signers may have developed an "internal justification"
for long-term continuation of the desired response.
A straightforward explanation is simply
necessary
that the
commitment/incentive intervention was successful at producing response
maintenance because people developed a habit of wearing their safety
60
belts. Another way of saying this is that the safety belt wearing
behavior came under the control of discriminative stimuli which had the
effect of directing the persons behavior in the absence of conscious
choices. In other words, because of repeated occurrences, the wearing
of safety belts became an automatic response that no longer invoked
active cognitive processing.
A surprising result was the absence of a main effect for time of
observation (morning vs. afternoon). It was hypothesized that safety
belt usage would be substantively higher du ring the afternoon because
more people were exposed to the observers immediately before the
opportunity to buckle-up. During the afternoon shift change most of
the observations included people leaving the hospital, while in the
morning most of the employees arrived at the hospital. Therefore, the
magnitude of the effect due to the presence of the observers should be
much less in the morning when much fewer staff members were exposed
to the observers. The absence of a significant difference suggests at
least three explanations. First, safety belt wearing may have
generalized across locations such that people, when coming to work,
buckle-up just as often as when they leave from work. Second, the
presence of the observers may not have had the hypothesized observer
presence effects. Repeated exposure to a familiar stimulus can produce
habituation. This is important, for if subjects were not responding to
the presence of the observers, the validity of the results were
strengthened (cf., Cook & Campbell, 1979). Finally, results from other
studies (cf. Geller, 1983; Geller & Hahn, 1984) found more wearing in
61
the A.M. than P.M. Maybe there was an observer presence effect, but
the effect was neutralized by "the rush of employees to get home from
work.
The hypothesis that non-pledge card signers would show an
increase in safety belt use was confirmed. The belt wearing of the
non-signers usage increased during the intervention, even though they
were not eligible for the incentives. Three reasons are offered to
explain the observed effect. Given that more people were wearing their
safety belts, another form of social influence (i.e., modeling, Bandura,
1977) may have .been responsible for the observed increase.
Alternatively, another artifact, increased public awareness of the
intervention project and safety belts in general, may have made the
wearing of safety belts more salient to the non-participants and thus
spurred a slight increase in belt wearing. Finally, increased public
awareness of the life-saving potential of safety belts and the threat of
mandatory usage laws may have caused a steady, but slight increase in
safety belt usage.
Specific Analytic Issues
From the strict behavioral view the commitment/incentive program was
remarkably successful. The pattern of results was similar to other
commitment programs in that overall the level of safety belt usage
during the six-month intervention more than doubled the initial Baseline
level, from 15.6% to 34. 7%. During the withdrawal phase, the usage
dropped to 25.6% (a 39% increase over Baseline), while for the follow-up
phase the percentage of safety wearers rose to 28. 6% (a 45. 5% increase
. 62
over Baseline). Moreover, the mean level of safety belt usage for the
188 pledge card signers during the intervention phase was an
astounding 75.1%, a more than 15090 increase over the 29.4 90 Baseline
level. The pledge card signers usage levels decreased from 56. % at
withdrawal to 44.9% at the four-month follow-up evaluation (a 34.5%
increase over Baseline). Finally, even the non-pledge card signers
increased their safety belt usage from 11.8% at Baseline to 17.8% during
the intervention (a 66% increase), to 22. 1% at the four-month follow-up
(almost a doubling in the usage level). The behavioral perspective
provides a clear, visual, interpretation of the magnitude of the
intervention effects. Examination of Figure 1 demonstrates the program
was successful at motivating safety belt use. Further, examination of
Table 2 reveals that for those individuals who specifically received the
intervention, i.e., the pledge card signers, the intervention program
was remarkably successful at increasing safety belt usage, particularly
during the intervention phase.
The results from the ANOVA and Time Series procedures are not
as straightforward and clear as the behavioral perspective. In fact,
comparisons between the behavioral perspective and the two statistical
procedures are irrelevant because different criteria are used to assess
the intervention effects. Visual inspection of a pattern of means as
suggested by practical significance tests for the behavioral perspective
vs. comparison of F statistics and p values derived from calculations
involving variance and standard error estimates in the detection of
statistical significance for the ANOVA and Time Series procedures.
63
Therefore, the remaining discussion considers only the comparison of
the A NOVA vs. Time Series.
As discussed at length in the results section, when time series
data exhibit serial dependency, the data are autocorrelated.
Autocorrelated data violate the independence assumption which produces
biased estimates of the standard deviations. For example, the standard
deviations may be underestimated which results in greater F values and
subsequently, increased detection of statistical significance. Table 5
presents a summary of statistically significant differences detected by
pairwise comparisons within experimental conditions for the ANOVA and
the Time Series procedures. Several interesting issues are brought
forth by examination of Table 5. Most notably, the ANOVA procedure
detected 10 significant within phase comparisons for the overall sample
and the two pledge groups. In marked contrast, the Time Series
analysis revealed only three statistically reliable differences among
pairwise comparisons for the same groups. This difference suggests
that by failing to account for the dependency among adjacent
observations when analyzing time series data,
traditional analysis of variance procedures,
significant differences when in fact, none exist.
researchers employing
may claim statistically
A second startling result is the finding of two significant
differences for the Non-pledge group with the Time Series analysis
(i.e., Baseline x Intervention and Baseline x Follow-up) and only one
significant difference with the ANOVA procedure (i.e., Baseline vs.
Follow-up). This result is difficult to intuit, particularly in light of
64
Table S
Comparison of the Statistical Treatment Effects Detected by the Analysis of Variance and the Time Series Procedures
Pairwise Comparisons r--------------------------------------------
Procedure
ANOVA
Group
Overall
Non-pledge
Pledge
Time Series
B X I
X
X
Overall X
Non-pledge
Pledge
X
Note: X = Significant at E < .OS
B X W B x F I X W I x F w X F
X X X
X
X X X X
X
65
the fact that the ANOVA procedure detected ten significant differences
among the pairwise comparisons and the Time Series found only three.
At the present time the author cannot formulate a plausible explanation
to account for this counter-intuitive result.
Suggestions for Future Research
One suggestion is to bring the commitment construct back into the
laboratory. There appears to be several variables that may or may not
have either a direct or an indirect effect on commitment. For example,
each of the five methods Kiester (1971) suggested that could be used to
manipulate commitment should be investigated to determine the main and
interactive influences of each of these procedures. A second factor
that should be investigated, empirically, is the precise influence of
making a commitment public. And, if commitment can be influenced by
making an act public, than would making an act more public make the
commitment more binding? If a commitment intervention includes a
public exposure manipulation, is it really the commitment that is
motivating the individual or is it public humiliation.
A second suggestion is that future researchers should attempt to
design their methodologies so as to allow for the assessment the main
and interactive effects of incentive and commitment intervention
strategies.
Another possibility for future research efforts is the investigation
of the . hypothesis that pledge duration may be an empirical
operationalization of the commitment construct. And, as such, the
degree of commitment which is assumed to exist along a continuum would
66
be indicated by longer commitment durations. The behavioral result
would be increased rate of safety belt wearing and longer maintenance
of the buckle-up response. The predicted effects can be verified
empirically by behavioral observation.
A fourth suggestion is that researchers continue the pursuit of the
elusive, delicate balance that appears to exist between intrinsic and
extrinsic motivation that will produce maximum success in maintaining
behavior change over the long term.
Finally, researchers are encouraged to consider analyzing their
time series data with the ARIMA procedure rather than the ANOVA
procedure when the data exhibit autocorrelation. Failure to do so can
lead to incorrect conclusions derived from biased statistical significance
tests.
References
Bachman, W., & Katzev, R. (1982). The effects of non-contingent free bus tickets and personal commitment on urban bus ridership. Transportation Research, 16A, 103-108.
Bandura, A. (1977). Self-efficiency: Toward a unifying theory of behavior change. Psychological Review, 811, 141-215.
Becker, L. J. (1978). The joint effect of feedback and goal setting on performance: A field study of residential energy conservation. Journal of Applied Psychology, 63, 228-233.
Bern, D. J. (1967). Self-perception: An alternative interpretation of cognitive dissonance phenomena. Psychological Review, 711, 183-200.
Bern, D. J. (1972). Self-perception theory. In L. Berlowitz (Ed.), Advances in experimental social psychology, (Vol. 6). New York: Academic Press.
Bigelow, B. E. (1982). The NHTSA program of safety belt research. SAE Technical Paper Series (No. 820797), 400 Commonwealth Drive, Warrendale, PA.
Box, G. E. P., & Jenkins, G. M. (1976). Time-series analysis: Forcasting and control. San Francisco: Holden-Day.
Campbell, B. J., Hunter, W., & Gemming, M. (1983). Seat belts pay off: A community wide research/public service project designed to increase use of lap and shoulder belts. Interim Report, University of North Carolina, Highway Safety Research Center, Chapel Hill, NC.
Campbell, B. J., Hunter, W.W., Stewart, J. R., & Stutts, J.C. (1982). Increasing safety belt use through an incentive program. Final report for Innovative Grant Project 4-A22 from the U.S. Department of Transportation, University of North Carolina, Highway Safety Research Center, Chapel Hill, North Carolina.
"Car seats for kids: It's the law." (1981). McCall's, December, 109, 38.
Cialdini, R. 8., Cacioppo, J. T., Bassett, R., & Miller, J. A. (1978). Low-ball procedure for producing compliance: Commitment then cost. Journal of Personality and Social Psychology, 36, 463-476.
Cook, T. D., & Campbell, D. T. (1979). Quasi-experimentation: design and analysis issues for field settings. Chicago: Rand McNally.
67
68
Cope, J. G., Grossnickle, W. F., & Geller, E. S. (1985). An evaluation of three corporate strategies for safety belt promotion. Accident Analysis and Prevention, Under editorial review.
Crano, W. D., & Sivacek, J. (1984). The influence of incentive-aroused ambivalence on overjustification effects in attitude change. Journal of Experimental Social Psychology, 20, 137-158.
Cunliffe, A. P., DeAngelis, F., Foley, C., Lonero, L. P., Pierce, J. A., Siegel, C., Smutylo, T., & Stephen, K. M. (1975). The design and implementation of a seat belt education program. Paper presented at the annual conference of the transportation association of Canada, Calgary, Alberta, Canada.
Deci, E. L. (1975). Intrinsic Motivation. New York: Plenum.
Elman, D., & Killebrew, T. J. (1978). Incentives and seat belts: Changing a resistant behavior through extrinsic motivation. Journal of Applied Social Psychology, 8, 72-83.
Federal Register (1983, October). Federal motor vehicle safety standards
Occupant crash protection. (Vol. 48, No. 203), Washington, D. C.: Department of Transportation.
Fouts, R. (1985, October). Personal communication with the author.
Geller, E. S. motivating Department Polytechnic
(1981). Development of industry-based strategies for seat belt usage: Phase I. Quarterly Report for of Transportation Contract DTRS5681-C-0032. Virginia Institute and State University, Blacksburg, Virginia.
Geller, E. S. (1982). Development of industry-based strategies for motivating seat belt use. Final Report for Department of Transportation Contract DTRS5681-C-0032, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.
Geller, E. S. (1983). Rewarding safety belt usage at an industrial setting: Tests of treatment generality and response maintenance. Journal of Applied Behavior Analysis, 16, 43-56.
Geller, E. S. (1984). Motivating safety belt use with incentives: A critical review of the past and a look to the future. SAE Technical Paper Series (No. 840326). Warrendale, PA: Society of Automotive Engineers.
Geller, E. S., Casali, J. G., & Johnson, R. P. (1980). usage: A potential target for applied behavior analysis. Applied Behavior Analysis, 13, 94-100.
Seat-belt Journal of
69
Geller, E. S., Davis, L., & Spicer, rewards to promote seat belt usage: collar versus blue collar employees. Behavior Management, 5, 17 -29.
K. (1983). Industry-based Differential impact on white
Journal of Organizational
Geller, E. S., & Hahn, H. A. (1984). Promoting safety belt use at industrial sites: An effective program for blue collar employees. Professional Psychology: Research and Practice, 15, 553-564.
Geller, E. S., Johnson, R. P., & Pelton, S. L. (1982). Community-based interventions for encouraging safety belt use. American Journal of Community Psychology, 10, 183-195.
Geller, E. S., Paterson, L., & Talbott, E. (1982). analysis of incentive prompts for motivating seat Journal of Applied Behavior Analysis, 15, 403-415.
A behavioral belt usage.
Geller, E. S., & Rudd, J. R. (June, 1985). Universitywide incentives for encouraging safety belt use: A comprehensive evaluation. In Proceedings of the Fourth Symposium on Traffic Safety Effectiveness (Impact) Evaluation Projects, The National Safety Council, Chicago, 1 llinois.
Geller, E. S., Winett, R. A., & Everett, P. B. (1982). Preserving the environment: New strategies for behavior change. New York: Pergamon Press.
Halverson, R. R., & Pallack, M. S. (1978). Commitment, ego-involvement, and resistance to attack. Journal of Experimental Social Psychology, 14, 1-12.
Hazer, J. T., Aeschleman, S. R., Robertson, R. B. (1985). Decreasing junk food consumption: A comparison of self-perception theory and reinforcment theory. Motivation and Emotion, 9, 87-98.
Hieder, F. (1958). The psychology of interpersonal relations. New York: Wiley.
Horne, T. D., & Terry, T. (1983). Seatbelt sweepstakes -- An incentive program. SAE Technical Paper Series (No. 830474). Warrendale, PA: Society of Automotive Engineers, Inc.
Johnson, R. P., & Geller, E. S. (1984). Contingent versus noncontingent rewards for promoting seat belt usage. Journal of Community Psychology, 12, 113-122.
Judd, C. M., & Kenny, D. A. (1981). Estimating the effects of social interventions. Cambridge, England: Cambridge University Press.
Kahn, J. (1973). "Who wants safer cars?" World Magazine, 3, 25, 28,
70
59.
Kello, J. E., & Geller, E. S. (1985). for motivation auto safety-belt Manuscript in preparation.
Awareness and pledge strategies wearing in industrial settings.
Kelly, H. ( 1967) . Levine (Ed.), Lincoln, NB.
Attribution theory in social psychology. In D. Nebraska Symposium on Motivation (Vol. 15).
Kelly, H. (1973). The processes of causal attribution. American Psychologist, 28, 107-128.
Kiesler, C. A. (1971). The psychology of commitment: Experiments linking behavior to belief. New York: Academic Press.
Kiesler, C. A., commitment. 349-353.
& Sakumara, J. (1966). A test of a model for Journal of Personality and Social Psychology, 3,
Lepper, M. (1981). I ntrinsci and extrinsic motivation in children: Detrimental effects of superfluous social controls. In W. Collins (Ed.) Aspects of the development of competence: The Minnesota symposium on child psychology, 11./-, 155-160.
Lepper, M. ( 1983). Social control processes, attributions of motivation and the internalization of social values. In T. Higgins, D. Ruble, and W. Hartrup (Eds.), Social cognition and social behavior: A developmental perspective. San Francisco, CA: Jossey-Bass.
Long, N. D. (1983). Presentation at the Governor's 1983 Conference on Highway Safety, Charleston, SC.
Nichols, J. L. (1982). Effectiveness and efficiency of safety belt and child restraint usage programs. Unpublished manuscript. Washington, D.C.: U.S. Department of Transportation, National Highway Traffic Safety Administration.
Pabon, Sims, Smith, & Associates, Inc. (1983). Motivation of employers to encourage their employees to use safety belts: Phase II. (Contract No. DTNH 22-80-C-07439). Washington, D. C.: National Highway Traffic Safety Administration).
Pallack, M. S., & Cummings, N. (1976). Commitment and voluntary energy conservation. Journal of Personality and Social Psychology Bulletin, 2, 27-31.
Pardini, A. V., & Katzev, R. D. (1983). commitment on newspaper recycling. Systems, 13 245-254.
The effect of strength of Journal of Environmental
71
Phillips, B. M. (1980). Safety belt education program for employees: An evaluation study. (Final report for contract DOT-HS-7-01707). Washington, D.C.: U.S. Department of Transportation.
Pierce, J. A., Toomer, M., Gardner, N., Pang, H. C., & Orlowski, C. (October, 1976). Evaluation of the effect of seat belt legislation in Ontario: Preliminary report. Paper presented at the 13th Annual Meeting of the Traffic Injury Research Foundation of Canada, Ottawa, Canada.
Robertson, L. S. (1975). Safety belt use in automobiles with starter-interlock and buzzer-light reminder systems. American Journal of Public Health, 65, 1319-1325.
Rudd, J. R., & Geller, E. S. (1985). A university-based incentive program to increase safety belt use: Toward cost-effective institutionalization. Journal of Applied Behavior Analysis, 18, 215-226.
Schnelle, J. McNees, behavior 157-166.
G., Gendrich, J. G., Siegle, G. P., Thomas, M. M., & M. P. ( 1980). Mass media techniques for promoting change in the community. Environment and Behavior, 12,
Skinner, B. F. (1953). Science and human behavior. New York: Macmillan.
Skinner, B. F. (1958). Science of human behavior. New York: Macmillan.
Skinner, B. F. (1938). The behavior of organisms. New York: Appleton-Century-Crofts.
Sleet, D. A. (1984). A preventative health orientation in safety belt and child safety seat use. SAE Technical Paper Series (No. 840325). Warrendale, PA: Society of Automotive Engineers.
Steed, D. (1983). Alcohol and safety belts. Keynote address at the National Conference on Alcohol Counter Measures and Occupant Protection, Lifesavers 2, Denver, CO.
Stern , P. & Aronson, E. (Eds.), (1984). Energy Use: The human dimension. New York: W. H. Freeman.
Streff, F. M. (1984). Development of an autodea/ership program to promote safety belt use. Unpublished masters thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA.
Talton, A. E. (1984). Increasing safety belt usage through personal
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commitment: A church-based pledge card program. Unpublished masters thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA.
Thorndike, E. L. (1911). Animal intelligence. New York:Macmillan.
Transportation Research Board (1980). Study of methods for increasing safety belt use: Study report. (Technical Report UR17 prepared for U.S. Congress and U.S. Department of Transportation). Washington, D.C.: Author, March.
"U.S. is trying safety 'bribes"' (1983). The New York Times, November 6.
Westefeld, A., & Phillips, B. M. (1976). Safety belt interlock system usage survey (Technical Report DOT-H5-801). Princeton, N.J.: Opinion Research Corporation.
Appendix A
Data Collection Sheet for Daily Collection of Safety Belt Usage.
73
,
Location __________ _
Ptlver an6 Paaaenger Code 0 • Shb not evailable
Ob•erver
l • Shb available, not vearins 2 • Shb available, vearing I • Kale ·
74
Obaerver 2 ________ _
Pledge Card (PC) .,. • Pledge Card on dashboard
Date ____________ _ Time Start. _____ _ Time Stop _____ _
D P PC Lic:enee D p PC L4 ....... D II
Appendix B
Buckle Up for Bucks Campaign Bulletin.
75
\() r--
ARE YOU READY TO -- BUCKLE-UP FOR BUCK~ -
"Buckle-Up For Bucks" is a safety belt program that's being implemented by the office of community relations in conjunction with Dr. Scott Geller and bis assistants from the department of psychology at Virginia Tech.
The six-month campaign bas been designed as a contest that will offer cash incentives to participants who buckle up.
But before we ask you to buckle-up we'd like to tell you why buckling-up is such a fantastic idea. So, for more information on the Buckle-Up For Bucks attend the 15 minute in-service programs on Thursday May 24 at 7:00 p.m. and 10:30 a.m. or 1:00 p.m.
HOW BUCKLE-UP FOR BUCKS WORKS
Participation in the Buckle-Up For Bucks program is open to any member of the hospital family. This includes employees, vol\m-teers, board members, and the medical staff.
To become a participant in buckle-up for bucks:
1) Simply !ill out~ partT of the attached pledge £!!_rds. be entire pledge card must be filled out to win. This includes circl-ing the duration for which you wish to participate. Return the small portion to tbe office of community relations.
2) Place the large portion Q!! the dash board of your~ The observers will need to be able to see the card in order to pick you as a winner. (contd. on back)
I u .
A Special UPDATE from RCH May 1 7, 1984 •
Appendix C
Pledge Card
77
Name
Phone#
License /'late #
Pledge Duration
I I
78
SAFETY BELT PLEDGE Take the Sa{ ety Belt Pledge
If Not For Yourself. For Someone You Love
1 (Signature) hrreby pledge to wear a ea{ety belt for the next (circle one) l week, J month, ,1 montM, 6 montha Btarting (today'• date) _______ , and I pledge to propt>rly securP all children riding in my vehicle in accordance wilh the Virginia Child Safety Seat Law.
I Radford) lhe Comn1ur1il y Hospital
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