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Journal of Educational Psychology1996, Vol. 88, No. 1,64-73
Copyright 1996 by the American Psychological Association,
Inc.0022-0663/96/$3.00
When Less Is More: Meaningful Learning From Visual and
VerbalSummaries of Science Textbook LessonsRichard E. Mayer,
William Bove, Alexandra Bryman, Rebecca Mars, and Lene
TapangcoUniversity of California, Santa Barbara
In a series of 3 experiments, college students who read a
summary that contained a sequenceof short captions with simple
illustrations depicting the main steps in the process of
lightningrecalled these steps and solved transfer problems as well
as or better than students whoreceived the full text along with the
summary or the full text alone. In Experiment 2, takingaway the
illustrations or the captions eliminated the effectiveness of the
summary. InExperiment 3, adding text to the summary reduced its
effectiveness. Implications for acognitive theory of multimedia
learning are discussed; implications for instructional
designpertain to the need for conciseness, coherence, and
coordination in presenting scientificexplanations.
Consider the following scenario. A student who is inex-perienced
in meteorology reads a textbook lesson explain-ing the
cause-and-effect chain of events involved in howlightning storms
develop. The explanation is clearly con-tained within the 600 words
and five illustrations of thelesson. A few minutes later, we ask
the student to writedown the explanation (as a retention test) and
to solve someproblems that require using the explanation from the
lesson(as a transfer test). For example, as a transfer problem,
weask the student to write an explanation for why there can
beclouds in the sky but no lightning. Despite exerting
consid-erable effort, the student performs poorly on both the
reten-tion and the transfer task, indicating a lack of
understandingof the process of lightning.
Unfortunately, this is not a made-up example, but ratherreflects
a pattern of results obtained frequently in our re-search
laboratory at Santa Barbara (Mayer, Steinhoff,Bower, & Mars,
1995). Students can carefully read a text-book lesson that contains
a scientific explanation, and yetnot be able to remember the
explanation adequately or touse it to solve problems. Given the
importance of textbooksas a commonly used vehicle for prom oting
student learning,evidence of students' difficulties in learning
from text isparticularly disturbing (Britton, Woodward, &
Binkley,1993; Driscoll, Moallem, Dick, & Kirby, 1994;
Garner,1992).This predicament raises the question of how to
helpstudents understand scientific explanations. By scientific
explanations, we mean cause-and-effect descriptions of aprocess,
such as the step-by-step description of the processof how lightning
develops. By understanding, we mean theability to apply what is
learned to solving new problems,Richard E. Mayer, William Bove,
Alexandra Bryman, RebeccaMars, and Lene Tapangco, Department of
Psychology, Universityof California, Santa Barbara.Correspondence
concerning this article should be addressed toRichard E. Mayer,
Department of Psychology, University of Cal-ifornia, Santa Barbara,
California 93106. Electronic mail may besent via Internet to
[email protected].
such as by answering transfer questions. By helping stu-dents,
we mean a modification to the textbook lesson, suchas the use of a
summary presented in words and illustra-tions.The goal of this
article is to examine an instructionaltechnique as a candidate for
promoting student understand-ing of scientific explanations,
namely, the use of a specialkind of summary that combines visual
and verbal informa-tion. During the past decade, researchers have
increasinglydemonstrated the role of illustrations in improving the
un-derstandability of textbook passages (Houghton &
Willows,1987; Mandl & Levin, 1989; Schnotz & Kulhavy,
1994;Willows & Houghton, 1987); in particular, researchers
havedemonstrated the value of combining text captions
withillustrations to create annotated illustrations (Bernard,
1990;Guri-Rozenblit, 1988). Following Levin's (1982) taxonomyof
illustrations, Mayer (1993) showed that the type of illus-tration
best suited for summarizing a scientific explanationis an
explanative illustration: a sequence of frames depictingthe major
steps in a process, such as the stages in theformation of
lightning. Furthermore, in a systematic seriesof studies,
explanative illustrations were most effective inpromoting retention
and transfer when they included con-cise captions describing each
frame in words (Mayer, 1989;Mayer & Gallini, 1990; Mayer et
al., 1995). In short,previous research has established the value of
a series ofannotated illustrations as an adjunct to a text passage;
thecurrent study takes this work one step further by exam
iningwhether a series of annotated illustrations constitutes
auseful summary that, instead of serving as an adjunct to text,can
stand alone.
The main focus of this study is on what can be called
amultimedia summary: a sequence of annotated illustrationsdepicting
the steps in a process. For example, Figure 1presents a summary of
the cause-and-effect explanation forthe process of lightning. The
essential elements of thissummary are that (a) the explanation is
presented in a shortsequence of simple illustrations depicting the
major steps inthe process; (b) the explanation is presented in a
shortsequence of brief sentences describing the major steps in
the64
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LEARNING FROM SUMMARIES 65
BrandUpward-moving
tepped leader
1. W arm moist air rises , water vaporcondenses and forms cloud.
4. Two leaders meet, negativelycharged particles rush from cloudto
ground.iwndrafts
2. Raindrops and ice crystals dragair downward. 5. Positively
charged particlesfrom the ground rush upwardalong the same
path.
Positively[ed particles
Negatavcharged particles
3. Negatively charged particles fallto bottom of cloud.Figure 1.
A multimedia summary of the process of lightning.
process; and (c) the visual and verbal explanations
arecoordinated so that each visual illustration contains a
cor-responding verbal caption.The essential features of this
summary are that it is (a)concise, (b) coherent, and (c)
coordinated. A summary isconcise if the visual explanation is
presented using only asmall number of simple illustrations and the
verbal expla-nation is presented using only a small number of
words.Furthermore, a summary is concise if these explanationsrefer
only to a small number of the parts and actions in thesystem,
namely, the parts and actions that are essential forthe
explanation. A summary is coherent if the visual andverbal
explanations are each given as sequential cause-and-effect chains
and a change in the state of one part of thesystem is clearly
related to a change in the state of anotherpart of the system. A
summary is coordinated if each step inthe explanation is presented
in visual form and verbal formso that corresponding illustrations
and words are presentedtogether.The theoretical rationale for these
three features of sum-maries can be found in a cognitive theory of
multimedia
learning (Mayer & Anderson, 1991, 1992; Mayer et al.,1995),
which is based on elements of dual-coding theory(Clark &
Paivio, 1991; Paivio, 1990), cognitive-load theory(Mousavi, Low,
& Sweller, 1995; Sweller & Chandler,1994; Sweller,
Chandler, Tierney, & Cooper, 1990), andgenerative theory
(Wittrock, 1974, 1989). As summarizedin Figure 2, a cognitive
theory of multimedia learning isbased on the idea that meaningful
learning requires that thelearner engage in five active cognitive
processes: selectingwords, selecting images, organizing words,
organizing im-ages, and integrating words and images.The cognitive
process of selecting words involves build-ing a mental
representation in verbal working memory ofthe basic propositions in
the explanation, such as "negative-ly-charged particles fall to
bottom of cloud." The cognitiveprocess of selecting images involves
building a mentalrepresentation in visual working memory of the
basic im-ages in the explanation such as an image of a cloud
withnegative signs toward the bottom. The cognitive process
oforganizing words involves building internal connections
among the propositions such that the statement
"negativelycharged particles fall to bottom of cloud" follows
"icecrystals drag air downward" and is followed by
"negativelycharged particles rush from cloud to ground." The
cognitiveprocess of organizing images involves building
internalconnections among the images such that an image of
neg-ative charges in the bottom of a cloud is followed by animage
of negative charges moving from the bottom of thecloud toward the
ground, which is followed by an image ofpositive charges moving
from the ground toward the bottomof the cloud. Finally, the
cognitive process of integratinginvolves building external
connections between a proposi-tion such as "negatively charged
particles fall to bottom ofcloud" and a corresponding image such as
of negativecharges at the bottom of a cloud.
The cognitive rationale for conciseness is that a concisesummary
allows the learner to select the relevant words andimages. By
paying attention to the relevant material, thelearner is able to
build verbal and visual mental represen-tations of the major states
of the system. The cognitiverationale for coherence is that a
coherent summary allowsthe learner to organize the relevant words
and the relevantimages into respective cause-and-effect chains. By
organiz-ing the relevant material, the learner is able to build
con-nections among the pieces of verbal information, yielding
averbal model, and to build connections among the pieces ofvisual
information, yielding a visual model. Finally, thecognitive
rationale for coordination is that a coordinatedsummary allows the
learner to build connections betweenthe visual and verbal
representations of the process.
In summ ary, this study addresses three kinds of
questions:philosophical, instructional, and cognitive. The
philosophi-cal question is, What is scientific explanation? For p
urposesof this study, a scientific explanation is a
cause-and-effectdescription of a sequential process, such as the
steps in theformation of lightning as represented in Figure 1.
Theinstructional question is, How can instruction help
studentsunderstand a scientific explanation? The focus of this
studyis a straightforward instructional device that has been
shown
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66 MAYER, BOVE, BRYMAN, MARS, AND TAPANGCO
S T E P l :SELECT WORDSSTEP 2:SELECT IMAGES
SUMMARY:"negatively chargedparticles fall to bottom ofcloud" _
|
fall (negatively chargedparticles, bottom of cloud)
VERBAL WORKING MEMORY VISUAL WORKING MEMORY
STEP 3:ORGANIZE W ORDSSTEP 4:ORGANIZE IMAGES
drag (ice cry stals, air(downward))
fall (negatively chargedparticles, bottom of cloud)V ER BA L WO
RK IN G MEM OR Y V IS UA L W OR KIN G ME MO RY
STEP 5:INTEGRATE WORDSAND IMAGESdrag (ice crystals,
air(downward))
1Tfall (negatively chargedparticles, bottom of cloud)V ER BA L
WO RK IN G MEM ORY V IS UA L WO RK IN G ME MO RY
Figure 2. A cognitive theory of multimedia learning.
to have some potential in promoting retention and transferof
scientific explan ations, namely, a summ ary in the form ofa
sequence of annotated illustrations as exemplified in Fig-ure 1.
The cognitive question is, Why do annotated illus-trations help
students understand scientific explanations?The theoretical
framework used to address this question is acognitive theory of
multimedia learning that involves theselecting, organizing, and
integrating of visual and verbalrepresentations.
Experiment 1Previous research has identified an effective
technique forhelping students understand scientific textbook
explanationsof how a cause-and-effect system works: adding a
briefsummary of the steps in the process depicted by a series
ofannotated illustrations (Mayer et al., 1995). In Experiment1, we
examined w hether reading a summ ary (summary-onlygroup) is as
effective in promoting retention and transferperformance as reading
the full passage along with thesummary (passage-and-summary group)
or the full textwithout the summary (passage-only group). A
no-instruc-
tion group was included to provide a baseline for compar-ison of
retention and transfer scores.One function of annotated
illustrations is to guide thelearner's attention toward the verbal
explanation given inthe annotation, which fosters the construction
of a verbalrepresentation of the explanative material.
Consequently,we predicted higher recall scores for groups that
receivedthe explanative information in annotated illustrations
(i.e.,summary-only and passage-and-summary groups) thangroups that
did not receive the explanative informationpresented in annotations
(passage-only and no-instructiongroups). A more focused prediction
was that students in thesummary-only group would recall more
explanative infor-mation than students in the passage-and-summary
group,because the summary-only students could focus their
atten-tion solely on relevant words, whereas passage-and-sum-mary
students had to read many words that were not part ofthe
explanation.A second function of annotated illustrations is to
encour-age the learner to organize the material into a
cause-and-effect system and to integrate the verbal and visual
repre-sentations of the system. A cognitive theory of
multimedialearning requires that students build representational
con-
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LEARNING FROM SUMMARIES 67nections (i.e., verbal and visual
representations of the ex-planations) and referential connections
between the visualand verbal representations. The groups that are
best sup-ported in building connections between words and
picturesare those receiving annotated illustrations
(summary-onlyand passage-and-summary groups), so we predicted
thesegroups would outperform all others on the
problem-solvingtransfer test. A more focused prediction was that
the sum-mary-only group would perform as well as or better than
thepassage-and-summary group on the problem-solving trans-fer
test.
MethodParticipants and design. The participants were 56 college
stu-dents who lacked experience in meteorology. They w ere
recruitedfrom the Psychology Subject Pool at the University of
California,Santa Barbara, and they fulfilled a class requirement by
partici-pating in the study. Fourteen participants served in each
of fourinstructional groups: passage-and-summary, passage-alone,
sum-
mary-alone, and no-instruction.Materials. The materials
consisted of a participant question-naire, three instructional
booklets, a recall sheet, and four problem-solving transfer sheets,
each typed on 8.5- X 11-in. sheets ofpaper.The participant
questionnaire asked students to rate their knowl-edge of
meteorology (orweather) on a 5-point scale ranging fromvery little
to very much and to place a check mark next to each ofseven items
that applied to them, including the following: "Iregularly read the
weather maps in a newspaper," "I know what acold front is," "I can
distinguish between cumulous and nimbusclouds," "I know what a low
pressure system is," "I can explainwhat makes the wind blow," "I
know what this symbol means"(symbol for cold front), and "I know
what this symbol means"(symbol for warm front).The
passage-and-summary booklet consisted of two sheets ar-ranged in a
folder as facing pages in an open book. The sheetscontained a
600-word passage (which we refer to as the passage)and five
captioned illustrations showing how lightning works(which we refer
to as the summary). The passage was created bythe authors on the
basis of high school science textbooks andencyclopedia entries,
including the World Book Encyclopedia's(1992) entry for lightning.
In addition to factual information de-scribing the properties of
lightning, the passage included a presen-tation of the chain of
causes andeffects that constitutes an expla-nation of how a
lightning storm develops. In the summary, fiveillustrations
depicted events in the cause-and-effect chain, such aswarm moist
air rising to form a cloud. Each illustration was placednext to its
corresponding paragraph that described the eventsdepicted in the
illustration; each illustration contained a shortcaption that
repeated the description of cause-and-effect eventsfrom the
corresponding text in the passage (requiring 48 w ords forall
illustrations); and each illustration contained labels that
re-peated key terms from the passage (requiring 30 words for
allillustrations). This booklet is identical to the integrated
bookletused by Mayer et al. (1995).The passage-alone booklet was
identical to the passage-and-summary booklet except that the
summary was deleted. The sum-mary-alone booklet was identical to
the passage-and-summarybooklet except that the passage was deleted,
as shown in Figure 1.The recall sheet consisted of a statement
asking the student towrite down an explanation of how lightning
works.Each problem-solving transfer sheet contained one of the
fol-
lowing four problems: (a) "What could you do to decrease
theintensity of a lightning storm ?" (b) "Suppose you see clouds in
thesky, but no lightning. Why not?" (c) "What does air
temperaturehave to do with lightning?" (d) "What causes
lightning?"Procedure. Participants were randomly assigned to
treatmentgroups and tested in small groups of 1 to 3 per session.
Conditionswere throroughly randomized w ith respect to time of day,
time ofweek, andweek of the academic quarter. The same
experimenteradministered the experiment for all participants in all
conditions.All participants in a session received the same
treatment. Eachparticipant was seated in an individual booth that
contained a deskand partitions on three sides. First, the
participant filled out theparticipant questionnaire. Participants
who indicated a lack ofknowledge of meteorology on the participant
questionnaire (i.e.,those who rated their knowledge as "very
little" or next to "verylittle" and who checked fewer than three
items on the checklist)were classified as low-experience learners.
Participants who werenot classified as low-experience learners (n =
5) were not includedin the experiment. Second, participants in the
passage-and-sum-mary, passage-alone, and summary-alone groups were
given 5 minto read their corresponding instructional booklet. They
were told toread carefully and that afterward they would be asked
somequestions about what they had read. The instructional
conditionswere contained in the booklets that students read
silently whileworking independently. Participants in the
no-instruction groupskipped this phase of the study. Next, the
booklets were collected.All participants were given the recall
sheet and asked to writedown all they could about how lightning
works in 6 min. Finally,following instructions, participants were
given 2.5 min to generateas many answers as possible for each of
the four problem-solvingquestions, presented one at a time in the
order previouslyindicated.
ResultsScoring. On the recall test, participants received
onepoint for each of the major idea units they produced, even
if
their wording differed from the original. The eight idea
unitsare major actions in the cause-and-effect chain and
werecontained both in the passage and in the summary. The eightidea
units are as follows: (1) warm, moist air rises; (2) watervapor
condenses (or water vapor forms clouds); (3) rain-drops and ice
crystals fall; (4) air is dragged downward; (5)negatively charged
particles fall (or move) to the bottom ofthe cloud; (6) two leaders
meet; (7) negatively chargedparticles rush (or move) from cloud to
ground (or down);and (8) positively charged particles move from
groundupward along the same path.
On the transfer test, participants received one point foreach
acceptable answer on each of the four problem-solvingtransfer
sheets, so that the total possible score was unlim-ited. A list of
acceptable answers was established for each ofthe four transfer
questions, although answers did not have tocorrespond verbatim. For
example, among the acceptableanswers for the first question were to
add positively chargedparticles to the cloud and to warm up the
cloud so nofreezing takes place. For the second question, an
acceptableanswer was that the cloud was not high enough to be at
thefreezing level or that not enough negatively charged parti-cles
were in the cloud. For the third question, an acceptableanswer was
that there is a difference in temperature between
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68 MAYER, BOVE, BRYMAN, MARS, AND TAPANGCOthe surface and the
air or that the cloud's top must be at thefreezing level. For the
fourth q uestion, an acceptable answerwas that a difference exists
between negative and positiveparticles or that there is a
temperature difference within thecloud.Hypothesis 1: Students who
receive summaries recallmore explanative information than students
who do notreceive summaries. The first hypothesis in Experiment
1was that when students receive verbal summaries (i.e., cap-tions
in the illustrations) that concisely state the to-be-recalled
explanation, they are more likely to attend to theverbal
explanation than when they do not receive verbalsummaries. In our
studies, the eight key explanative piecesof information are
presented in the summary as well as inthe passage; however, the
passage contains much additionalinformation, whereas the verbal
summaries contain only theeight explanative idea units. For this
reason, we expect thesummaries to guide the learner's attention
toward theseeight explanative idea units and to encourage the
learner toconstruct a verbal representation of the explanation.
The left panel of Figure 3 shows the mean number ofexplanative
idea units (out of eight) produced by each of thefour groups.
Consistent with the hypothesis, a one-wayanalysis of variance (AN
OVA) revealed significant differ-ences among the groups, F(3, 52) =
43.05, MSE = 1.66,p < .001. Supplemental Tukey tests (with alpha
at .05)indicated that students who received no instruction
(no-instruction group) produced fewer explanative idea unitsthan
students in each of three groups that received a book letto read,
confirming the observation that the instructionalmaterials
contributed to student learning and that the pas-sage-alone group
did not differ significantly from the pas-sage-and-summary group.
More important, students whoreceived the summary-alone booklet
outperformed each ofthe other groups, indicating that in this case
"less is more";that is, students recalled mo re explanative
information w henthey received the annotated illustrations alone
than whenthey received the full text passage along with the
annotatedillustrations. Similar results have been obtained in
otherstudies on text summaries (Britton, Gulgoz, & Glynn,
1993;Reder & Anderson, 1980).These results may be biased
because the inclusion of theno-instruction group artificially
reduced the MSE. To over-come this problem, we recomputed the
foregoing ANOVA
with just three groups: passage-and-summary, summary-alone, and
passage-alone. As in the previous analysis, thethree groups
differed significantly in number of idea unitsrecalled, F(2, 39) =
10.97, MSE = 2.16, p < .001, andsupplemental Tukey tests (with
alpha at .05) revealed thatthe summary-alone group recalled more
idea units thaneither of the other groups, which did not differ
from oneanother.Overall, these results are consistent with the idea
thatannotated illustrations help the learner to focus on
keyexplanative information because the explanations are pre-sented
without any distracting verbal information; evenwhen the identical
verbal explanative information is pre-sented within the text
passage, students are less likely toencode it because they attend
to nonexplanative informationin the text passage. In short, we
interpret these results asconsistent with one hypothesized function
of annotated il-lustrations, namely, that annotated illustrations
help to guidethe learner's attention toward explanative
information.A possible criticism of using recall as a dependent
mea-
sure is that students in the passage-and-summ ary group mayspend
most of their test time writing down nonexplanativeinformation,
whereas summary-only students may spend allof their time w riting
dow n explanative information. In spiteof the recall results,
therefore, students in the passage-and-summary group may actually
know more about the expla-nation than do summary-alone students. To
examine thispossibility, in the next subsection we focused on
problem-solving transfer as the primary dependent measure for
as-sessing students' understanding of the explanation of
howlightning develops.Hypothesis 2: Students who receive summaries
generatemore creative solutions to problem-solving questions
than
students who do not receive summaries. Our second hy-pothesis is
based on the idea that annotated illustrations helpthe learner to
construct connections between verbal andvisual representations of
the explanation, which, in turn,supports problem-solving transfer.
The right panel of Figure3 shows the mean num ber of creative
solutions generated byeach group on the transfer test. Consistent
with the hypoth-esis, a one-way analysis of variance revealed that
the groupsdiffered significantly from one another, F(3, 52) =
21.45,MSE = 3.05, p < .001. Supplemental Tukey tests (withalpha
at .05) showed that students who did not receive
Passage-and-summarySummary-alone
Passage-aloneNo-instruction
Explanative recall
1..1 2 3 4 5Mean number of idea units recalled
Problem-snlving transfer^
i i i i i
1 2 3 4 5Mean number of problem solutionsFigure 3. Experiment 1:
Mean number of explanative statements produced on the retention
testand mean number of acceptable solutions produced on the
transfer test for four treatment groups.
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LEARNING FROM SUMMARIES 69instruction (i.e., no-instruction
group) performed morepoorly than those in each of the other groups;
more impor-tant, the two groups who received a summary (i.e.,
summa-ry-alone and passage-and-summary groups) performed bet-ter
than the other groups but did not differ from one ano ther.Again,
these results may be biased because the inclusionof the
no-instruction group artificially reduced the MSE. Toovercome this
problem, we recomputed the foregoingANOVA with just three groups:
passage-and-summary,summary-alone, and passage-alone. As in the
previous anal-ysis, the three groups differed significantly in
number ofcreative solutions produced on the transfer test, F(2, 39)
=6.86, MSE = 4.05, p < .001, and supplemental Tukey tests(with
alpha at .05) revealed that the passage-alone groupproduced fewer
solutions than either of the other groups,which did not differ from
one another.Interestingly, adding the text passage to the
annotatedillustrations did not increase transfer performance over
sim-ply presenting the annotated illustrations alone. Put
anotherway, the uninstructed group generated the fewest number
ofsolutions, the passage-alone group generated considerablymore
than the uninstructed group, and the two groups re-ceiving
annotated illustrations each generated approxi-mately 100% more
than the passage-alone group. This pat-tern of results is
consistent with the prediction that asummary is as effective as a
full text along with a summ aryin helping learners to understand a
scientific explanation.
Exper imen t 2Experiment 1 yielded the findings that (a) a
visual andverbal summary of a passage is more effective than a
fullpassage in helping students to remember and to use an
explanation of how lightning occurs and (b) a visual andverbal
summary is more effective in helping students re-member an
explanation and just as effective in helpingstudents use an
explanation compared to the combination ofa full text passage with
a visual and verbal summary. Thesummary in Experiment 1 was a set
of five annotatedillustrations that contained both a visual summary
(i.e., fiveframes of illustrations) and a verbal summary (i.e.,
verbalcaptions and labels for each illustration). In Experiment
2,we attempted to untangle the contributions of the visual
andverbal aspects of the summ ary by asking students to read
thesame passage and summary as in Experiment 1, the samesummary as
in Experiment 1, a summary containing wordsonly, or a summary
containing illustrations only. If theeffectiveness of the summary
depends on the learner's con-struction of connections between
verbal and visual expla-nations, as stipulated by a cognitive
theory of multimedialearning, it follows that students receiving
the visual-and-verbal summary will perform better on transfer tests
thanstudents receiving the visual summary alone or the
verbalsummary alone.Method
Participants and design. The participants were 68 college
stu-dents who lacked knowledge of meteorology and who were re-
cruited from the Psychology Subject Pool at the University
ofCalifornia, Santa Barbara. Seventeen students served in each
offour treatment groups: passage-and-summary,
summary-alone,verbal-summary-alone, and
visual-summary-alone.Materials. The participant questionnaire,
retention sheet, andfour problem-solving transfer sheets were
identical to those used inExperiment 1. The passage-and-summary
booklet and the summ a-ry-alone booklet were identical to those
used in Experiment 1. Theverbal-summ ary-alone booklet was
identical to the sum mary-alonebooklet except that all
illustrations were deleted; the visual-sum-mary-alone booklet was
identical to the summary-alone bookletexcept that all words (i.e.,
captions and labels) were deleted.
Procedure. The procedure w as identical to that used in
Exper-iment 1 except that during the study period, students
receivedeither the passage-and-summary, summary-alone,
verbal-summa-ry-alone, or visual-summary-alone booklet.
Results and DiscussionScoring. The retention and transfer tests
were scored asin Experiment 1.Hypothesis 3: Students who receive
summaries performas well as or better than students who receive
passages withsumm aries on tests of retention and transfer. A
secondarygoal of Experiment 2 was to determine whether the
resultsof Experiment 1 could be replicated. As in Experiment 1,the
summary-alone group recalled more explanative ideaunits than the
passage-and-summary group (Ms = 5.94 and3.45, respectively), f(32)
= 4.43, p < .001. Also as inExperiment 1, the summary-alone
group performed as wellon the transfer test as the
passage-and-summary group; infact, in contrast to Experiment 1, the
summary-alone groupproduced significantly more creative solutions
than the pas-sage-and-summary group (M s = 5.00 and 3.85,
respective-
ly), f(32) = 2.06, p < .05. Taken together, the results
ofExperiments 1 and 2 show that a summary, in the form ofannotated
illustrations, can be either as effective as or moreeffective than
a full passage combined with a summaryin helping students to
remember and to use a scientificexplanation.Hypothesis 4: Students
who receive summaries contain-ing verbal information recall more
explanative informationthan students who receive summaries that do
not containverbal information. The main goal of Experiment 2 was
todetermine whether a visual summary (i.e., a series of
fiveillustrations depicting the major events in the process
oflightning), a verbal summary (i.e., a series of five
captionsdescribing the major events in the process of lightning),
orboth, are needed to produce an effective summary.The left panel
of Figure 4 shows the mean number ofexplanative idea units produced
on the retention test. Ananalysis of variance performed on the
recall data revealedthat the four treatment groups differed
significantly in themean number of idea units recalled, F(3, 64) =
50.25,MSE = 2.27, p < .001 . Supplemental Tu key tests
(withalpha at .05) revealed that the visual-summary-alone
groupproduced fewer explanative idea units than each of the
othergroups, presumably reflecting th e lack of verbally
presentedmaterial. More interestingly, the summary-alone and
verbal-summary-alone groups produced significantly more idea
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70 MAYER, BOVE, BRYMAN, MARS, AND TAPANGCOProblefn-RQlYJnP
transfer
Passage-and-summarySummary-alone
Verbal-summary-aloneVisual-summary-alone
1 2 3 4 5Mean number of idea units recalled 1 2 3 4 5Mean number
of problem solutions
Figure 4. Experiment 2: Mean number of explanative statements
produced on the retention testand mean number of acceptable
solutions produced on the transfer test for four treatment
groups.
units than either of the other two groups but did not differfrom
one another. If the goal of instruction is solely toproduce good
retention of a verbal explanation, the bestinstructional method
seems to be to provide the learner witha verbal explanation.
However, as noted in the previoussection, we focused on
problem-solving transfer as ourprimary measure of
understanding.
Hypothesis 5: Students who receive summaries contain-ing both
visual and verbal information produce more cre-ative solutions than
students who receive summaries con-taining only visual or only
verbal information. The rightpanel of Figure 4 shows the mean
number of creativesolutions produced on the problem-solving
transfer test foreach of the four treatment groups. An analysis of
variancerevealed that the groups differed significantly from
oneanother in the mean number of problem solutions, F(3,64) =
14.53, USE = 2.50, p < .001. Supplemental Tukeytests (with alpha
at .05) revealed that the summary-onlygroup did not differ
significantly from the passage-and-summary group, replicating the
results of Experiment 1.More imp ortant, a major new finding in
Experim ent 2 is thatthe summary-alone group outperformed both the
visual-summary-alone and the verbal-summary-alone groups.
Weinterpret these results as indicating that both verbal andvisual
aspects of the summary are useful in helping inex-perienced
learners build a coherent understanding of a sci-entific
explanation. It is interesting that, although studentsin the
verbal-summary-alone group remembered as much ofthe verbal
explanation as did students in the summary-alonegroup, they were
not as effective as the summary-alonestudents in applying their
verbal knowledge to solve prob-lems. If the goal of instruction is
to produce good retentionand transfer of scientific explanation,
then the best instruc-tional method seems to be a coordinated
verbal and visualsummary of the major steps in the to-be-explained
process.
In conclusion, the most effective summary, according toour
research, is one that coordinates a verbal and visualsummary of the
explanation, rather than one that summa-rizes the explanation only
in words or only in pictures.Exper imen t 3
Experiment 2 provided a replication of one of the majorfindings
in Experiment 1, in which students who read a
summary performed as well as or better than students whoread a
full text along with a summ ary. In addition, the majornew finding
in Exp eriment 2 was that the positive effects ofthe summary
occurred most strongly when both visual andverbal information were
presented and not when the sum-mary w as presented solely in verbal
form or solely in visualform. Thus, the results of Experiment 2
showed that takingaway the illustrations or the captions from the
summaryreduced its effectiveness.
This pattern is consistent with a cognitive theory of
mul-timedia learning, which states that both visual and
verbalrepresentations are needed to build referential
connections.When only a verbal summary is presented, an
inexperiencedlearner may be able to generate a verbal
representation butmay have difficulty in constructing a visual
representationon the basis of the verbal information; when only a
visualsummary is presented, an inexperienced learner may be ableto
generate a visual representation but may have difficultyin
constructing a verbal representation on the basis of thevisual
information.In Experiment 3, we examined the effects of adding
textto the captions in the summary. According to a cognitivetheory
of multimedia learning, adding text may disrupt theprocess of
selecting relevant wo rds. When extraneous text isadded, the
learner may have difficulty in identifying thecore steps in the
causal chain; this task is easier when thetext consists only of the
core steps in the causal chain. Itfollows that students who read a
summary will performbetter on tests of retention and transfer than
will studentswho read a summary containing additional words.
MethodParticipants and design. The participants were 39 college
stu-dents who lacked experience in meteorology. They w ere
recruitedfrom the Psychology Subject Pool at the University of
California,Santa Barbara, and they fulfilled a class requirement by
partici-pating in the study. Thirteen students served in each of
threeinstructional groups: summary, summary-plus-50-words,
summa-ry-plus-550 words.Materials. The materials consisted of the
same participantquestionnaire, recall sheet, and four
problem-solving transfersheets as in Experiments 1 and 2; in
addition, the materialsincluded three instructional books: the
summary booklet, a sum-mary-plus-50-words booklet, and a
summary-plus-550-words
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LEARNING FROM SUMMARIES 71booklet. The summary booklet was
identical to the one used inExperim ents 1 and 2; it contained five
captioned illustrations w ithapproximately 50 words in the
captions. The summary-plus-50-words booklet was the same as the
summary booklet except that amore in-depth description of each
illustration was given in eachcaption, yielding a total of
approximately 100 words in the cap-tions. Like the summary
captions, the expanded captions weretaken verbatim from the full
text passage used in Experiments 1and 2. The expanded captions were
as follows:
1. Warm moist air near the earth's surface rises. As the airin
this updraft cools, water vapor condenses into water drop-lets and
forms a cloud. The cloud's top extends beyond thefreezing level, so
tiny ice crystals form in the upper portion ofthe cloud.2.
Eventually, the ice crystals become too large to besuspended by
updrafts, so they fall through the cloud. Theydrag air downward,
producing downdrafts. When downdraftsstrike the ground they produce
gusts of cool wind.3. The rising water droplets collide with the
falling ice,producing electrical charges. Negatively charged
particles fallto the bottom of the cloud, and positively charged
particlesrise to the top.4. A negatively charged stepped leader
moves downwardfor the cloud in a series of steps. A positively
charged upward-moving leader travels up from the trees and
buildings to meetthe negative charges. When the two leaders meet,
negativelycharged particles rush from the cloud to the ground.5. As
the leader stroke nears the ground, it induces anopposite charge.
Positively charged particles from the groundrush upward along the
sam e path. This return stroke producesthe bright light that people
notice in a flash of lightning.
In the summary-plus-550 words booklet, the captions for the
fiveillustrations consisted of the entire 600-word passage as used
inExperiments 1 and 2. This is just like the
passage-and-summarycondition of the previous experiment but
presented in a differentformat, that is, each portion of text is
placed with its correspondingillustration.
Procedure. The procedure was identical to that used in
Exper-iments 1 and 2, except that during the study period,
studentsreceived either the summary, summary-plus-50-words, or
summa-ry-plus-550-words booklet.
Results and DiscussionScoring. The retention and transfer tests
were scored asin Experiment 1.
Hypothesis 6: Students who receive concise summariesrecall more
explanative information than students who re-ceive expanded
summaries. A major hypothesis in Exper-iment 3 is that students who
receive simple illustrations withbrief captions depicting the steps
in the process of lightningwill recall those steps better than will
students who receivesimple illustrations with longer captions. A
rationale for thisprediction is that lengthy captions may overload
verbalworking memory so that some of the explanative informa-tion
is lost.The left panel of Figure 5 shows the mean number
ofexplanative idea units (out of eight) produced by each of
thethree groups on the retention test. Consistent with the
hy-pothesis, a one-way ana lysis of variance revealed
significantdifferences among the groups in mean number of
explana-tive ideas recalled, F(2, 36) = 20.94, MSE = 2.15, p
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72 MAYER, BOVE, BRYMAN, MARS, AND TAPANGCOcreative solutions to
problem-solving questions than willstudents who receive simple
illustrations with longer cap-tions. A rationale for this
hypothesis is that lengthy ca ptionsmay overload verbal working
memory, disrupting the pro-cess of building a verbal representation
and connecting itwith a visual representation of the lightning
system.
The right panel of Figure 5 shows the mean number ofcreative
solutions generated by each group on the problem-solving transfer
test. An analysis of variance revealed sig-nificant differences
among the groups in their problem-solving performance, F(2, 36) =
3.19, MSE = 2.34, p =.05. Supplemental Tukey tests (with alpha at
.05) showedthat the summary group performed significantly better
thanthe summary-plus-550-words group on the problem-solvingtransfer
test but not better than the summary-plus-50-wordsgroup. These
results are consistent with the idea that addinga lot more text to
the captions can reduce students' effi-ciency in abstracting the
core verbal explanation and inconnecting it with the visual
explanation.
ConclusionWhen the goal of instruction is to help students be
able toexplain a scientific system in words (retention) and to
usethis explanation to solve problems (transfer), a
commoninstructional practice is to provide a lengthy verbal
expla-nation, such as a textbook passage or a classroom
lecture.Indeed, instructors may believe that providing a
lengthyverbal explanation fulfills their responsibility to
provideinformation to the learner. Unfortunately, this practice is
notvery efficient for many students, presumably because stu-dents
do not process the information effectively. In the
present study, for example, there was no instructional
treat-ment, including a 600-word passage with summary, thatproved
to be more effective in promoting retention andtransfer than a
summary. By reducing the load on thecognitive system, summaries may
enable students to carryout the cognitive processes necessary for
meaningful learn-ing as summarized in Figure 2.Our research extends
earlier research on text-based sum-maries (Reder & Anderson,
1980) by examining the natureof summaries that are based on both
text and illustrationswhat can be called multimedia summaries. In
particular, ourresearch suggests that a verbal summary is not as
effectiveas a multimedia summary that combines both visual
andverbal formats and that a multimedia summary is moreeffective
when it contains a small am ount of text rather thana large
amount.What constitutes an effective multimedia summary?
Ourmultimedia summary was constructed on the basis of
threecriteria: conciseness, in that only a few illustrations
andsentences were presented; coherence, in that the images
andsentences were presented in cause-and-effect sequence;
andcoordination, in that the images were presented contigu-ously
with their corresponding sentences (i.e., each illustra-tion had a
verbal caption). In Experiment 3, we varied theconciseness of the
verbal explanation and found evidencethat students learn more
effectively from a more concise
summary. In Experiment 2, we varied the coordination andfound
that students learn more effectively when words andillustrations
are presented together rather than separately (asa words-only or
illustrations-only treatment). However, wedid not directly compare
presenting a coordinated multime-dia summary (i.e., verbal captions
with each illustration)with presenting a verbal summary on a
different page froma visual summary. Furthermore, we did not vary
the coher-ence of the summaries by presenting the illustrations
andsentences in random order versus sequential order.The quality of
the verbal explanation is another issue thatdeserves additional
research attention, because well-writtentext may not have the same
effects as poorly written text.Although we attempted to use
well-written text in the 600-word passage, we may not have
succeeded. Therefore, ad-ditional research is needed to determine
whether or not thepassage-and-summary treatment would foster better
resultsif the quality of the passage was improved.Additional
limitations concern the n ature of the materials,the learners, and
the dependent measures. The materials
consisted of a scientific explanation of a
cause-and-effectprocess; if we had used a narrative or purely
descriptivepassage rather than an explanative passage, the results
mayhave been quite different. The learners were inexperiencedin the
subject domain; if we had used experienced learners,we would not
expect to find differences among the treat-ment groups. Finally, we
focused on retention and transferof the explanative information as
our dependent measures;if we had focused on overall amount remem
bered, we wouldnot expect to find the same kinds of differences
among thegroups. In short, these experiments p rovide new
informationconcerning the circumstances in which a summary is
effec-tive, namely, when the material is potentially
structured,when the learners do not norm ally identify the
structure, andwhen the summary conveys the structure visually
andverbally.Last, it would be incorrect to conclude that in all
casesstudents can learn as much from studying a summary asfrom
studying a full lesson along with a summary. Thisstudy provides
consistent evidence of a situation in which asummary can be
effective in promoting student understand-ing of a scientific
explanation. Further research is needed todetermine the role of
carefully constructed multim edia sum-maries that are sensitive to
the cognitive loads on visual andverbal working memories.
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