.I. &km. Thu. & Exp. Psyckiof. Vol. 12. No. I, pp. 87-90, 1981 Printed in Great Britain.

ooO5-7908/81/010087-04$02.00/O CI 1981 Pergamon Press Ltd.

PARENTAL CONTROL OF

NOCTURNAL THUMBSUCKING

MARY LEWIS, PAULA SHILTON* and R. WAYNE FUQUA

Western Michigan University

Summary-This study evaluates two procedures for the elimination of nocturnal thumbsucking in a lo-yr-old boy. The subject’s mother recorded the occurrence of thumbsucking four times each night. Reliability checks were done twice a week by another family member. A plastic splint, usually employed to protect a damaged thumb, was placed on the subject’s thumb at bedtime. The results showed that when the splint was used, the incidence of thumbsucking decreased from 100% of the checks made during baseline to 0% during intervention. Several naturallv occurrina and one manned reversal demonstrated the effectiveness of the splint in controlling thumbsucking.

Previous attempts to control nocturnal thumb- sucking have generally focused on some type of device designed to interfere with the response. Examples include: wrapping the arm with an elasticized bandage (Garliner, 1976); coating the thumb with a foul tasting substance (Ross, 1975); and wearing a glove to bed (Lassen & Fluet, 1978). Although these studies report promising results, problems such as lack of baseline, lack of reliability checks, or inadequate experimental design preclude definite conclu- sions about the effectiveness of the interventions.

Since there are no obvious reinforcers main- taining the nocturnal thumbsucking response, it seems likely that sensory stimulation is sufficiently reinforcing in itself to do so. If this could be eliminated or substantially re- duced, then such an intervention might prove effective in decreasing the thumbsucking be- havior. Eliminating or attenuating sensory stimulation has proven effective in reducing the rate of behaviors which are primarily controlled by their sensory consequences. Rin- cover and his associates (Rincover, 1978; Rin-

cover et al., 1979) used this strategy successfully to extinguish the self-stimulatory behavior of developmentally disabled children. Dorsey* extended Rincover’s work on sensory extinction to the control of self-injurious behaviors in developmentally disabled persons.

Although sensory extinction procedures are idiosyncratic to the type of stimulation that may be maintaining the behavior, they have several common characteristics: (a) the pro- cedure is used when the primary maintaining variable appears to be a response contingent change in sensory stimulation rather than some socially mediated reinforcer (e.g. praise); (b) it is used when the response is either of a very high rate or of long duration; (c) some type of device is used to attenuate the sensory changes produced by the response; (d) the sensory attenuating device is in place for a protracted period of time rather than for a brief period of time after each target response.

While the procedure in the present study meets each of these criteria, it is referred to as a sensory attenuation procedure, since the term

Requests for reprints should be addressed to R. Wayne Fuqua, Department of Psychology, Western Michigan University, Kalamazoo, Michigan 49008. *Now at Oregon Social Learning Center in Eugene, Oregon.

*Dorsey, M. Reduction and maintenance of self-injurious behavior in retarded persons using sensory extinction. Un- published Doctoral Dissertation, Western Michigan University, 1979.

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88 MARY LEWIS, PAULA SHIL.TON and R. WAYNE FUQUA

“extinction” implies the complete removal of a reinforcer. This procedure, while substantially altering the sensory stimuli, does not completely eliminate the thumbsucking.

Subject

METHOD

The subject was a IO-yr-old boy who, according to his parents, had sucked his thumb at night since infancy. The subject’s teeth were misaligned and required ortho- dontia, but his orthodontist advised that the effects of treamtent would be negated by continued thumbsucking. The subject’s mother reported that coating the thumb with a foul tasting substance and making the boy wear a glove had failed to eliminate the habit.

Dependent variable

Sensory aftenuation. A sensory attenuation procedure was then implemented and maintained for 21 consecutive nights. Before bedtime the subject’s mother taped a splint (Pallab plastic finger guard) onto his thumb with adhesive tape and removed it in the morning. The splint consisted of four parallel plastic prongs attached to a round cap. The device was slipped over the end of the thumb and was not of sufficient size to prevent the insertion of the thumb into the mouth. There were three nights during this phase when the device was worn for only part of the night, either because the subject refused to have it put on or because the mother forgot to do it. In all three instances the splint was put on after the subject went to sleep, but not before observations were made.

Baseline 2. A 7 night reversal occurred during which the splint was not worn and the reinforcement contingencies were not in effect.

The dependent variable was defined as the percentage of checks in which any portion of the subject’s thumb was in his mouth. The subject was observed by hi, mother four times each night: shortly after his bedtime, just before his mother went to bed, in the early morning when she woke her eldest child, and when she woke the subject. ‘Two reliability checks were conducted each week, either by the subject’s father or eldest brother. The reliability observers simply recorded the occurrence or non-occurrence of thumbsucking at the same time the mother scored the behaviors. The mother received a $4.00 rebate on her weekly counseling fee if data sheets were completed and reliability checks were made. This rebate was unrelated to the level of behavior reported by the mother in order to prevent any influence on the accuracy of the dara

Sensory altenua,ion. The thumb splint was again worn for 10 more nights. During this phase, there were 4 nights when the device was worn for only part of the night because the mother forgot to implement the procedure. Again, it was put on after the subject had fallen asleep but not before observations were made.

numb. Straightening the arm would relieve the numbness and necessitate removal of the thumb from the mouth. This procedure proved difficult to implement and was abandoned because of the following two problems: (a) the bandage was applied so loosely that it did not stay in place; (b) it was applied so tightly that there was some minor swelling in the hand.

RESULTS proCided by he;.

lndependenr variables The independent variables were two procedures, one

of which was designed to restrain the response and the other to attenuate the sensory stimulation produced by thumbsucking. Restraint, wrapping the arm with an elasticized bandage (condition B), and sensory attenuation, putting a thumbsplint on the thumb (condition C), were employed in an ABCAC design. During each intervention condition the subject was allowed to choose a quarter, a glass of pop or a trinket contingent upon compliance with treatment procedures. If he did not comply, his mother applied the device after he was asleep.

Baseline. Baseline data were collected for I week. At the end of this period, there was a 2 week delay in therapy because of parents’ vacation, during which time the mother conducted casual observations. She rimply checked for

Reliability (Agreements/Agreements and Dis- agreements x 100%) was 100% in all phases of this study.

As can be seen in Fig. 1, the subject’s thumb

was in his mouth 100% of the checks made during baseline. During the 2 week delay, the mother conducted casual observations and re- ported that the subject’s thumb was in his mouth 90% of the checks made (this is not shown on Fig. 1).

During restraint, thumbsucking occurred in an average of 54% of the checks made. Al- though there was a downward trend in the

the occurrence or non-occurrence of the- target response but made no attempt to respond differentially to the

data, it was decided to change the treatment

occurrence of thumbsucking. because of adverse side effects.

Re.ytrurnt. Restraint was in effect for 7 nights. An The next 11 nights, when the subject wore elasticized bandage was wrapped around the subject’, the thumb splint, were free of thumbsucking arm from just above the wrist to just below the shoulder and fastened with safety pins. The bandage was wrapped

at all check;. Following this, there were 5

tightly enough so that if the elbow was bent, blood flow nights when the thumb splint was worn for to the hand would be reduced and the hand would become only part of the night, and thumbsucking was

CONTROL OF NOCTURNAL THUMBSUCKING a9

Fig. 1. Percentage of nightly checks during which thumbsucking was observed.

observed on some portion of the observations. In all cases, the response occurred when the splint was not on the subject’s thumb. The next 7 nights were again free of thumbsucking, and the splint was on the entire night.

Thumbsucking rose to 100% of the checks made by the seventh night of the reversal phase.

Reinstituting the thumbsplint procedure again reduced the incidence of thumbsucking to zero at each of the checks made, except on nights when the mother forgot to implement the pro- cedure, and the splint was on for only part of this night.

DISCUSSION

The results indicate that sensory attenuation procedure was effective in controlling nocturnal thumbsucking in this subject. When the thumb- splint was worn the entire night, thumbsucking did not occur at any of the checks made. When the splint was not worn thumbsucking occurred at all of the checks made. Furthermore, it occurred at a percentage of the checks made when the splint was worn for only part of the night. It occurred when the splint was off, but not when the splint was on.

While thumbsucking was controlled in this subject for the duration of the case study, it was not eliminated. Factors beyond the control of the experimenters required that the mother

terminate therapy before a fading procedure could be implemented. Follow-up phone calls to the mother indicate that the thumbsplint is not being used and the subject is again sucking his thumb at night.

The fact that nocturnal thumbsucking con- tinued to occur when the thumbsplint was not used should not detract from the main finding of this study-the use of a thumbsplint was consistently associated with the absence of nocturnal thumbsucking. Whether treatment gains will be maintained in the absence of the initial behavior change intervention is a separate issue. Future research might focus on the ex- perimental validation of procedures which pro- mote the maintenance of treatment effects in the absence of the thumbsplint. For example, the obtrusiveness of the thumbsplint could gradually be reduced by systematically shorten- ing the prongs of the splint until only a small cap secured by a short piece of tape remained.

It should be noted that behavior changes continue in the absence of therapeutic inter- vention to the extent that they are maintained by naturally occurring reinforcers. These may not be sufficiently powerful to maintain those changes. In such cases, it may be necessary to prolong the initially effective therapeutic intervention (or a modified version) in order to maintain the required behavior. This ap- proach is analogous to the use of prosthetic

90 MARY LEWIS, PAULA SHILTON and R. WAYNE FUQUA

devices (e.g. eyeglasses, hearing aids) for certain medical problems. In any event, the identi- fication of effective interventions is essential to change behavior. Based on the data from this study, a thumbsplint appears to be an effective technique for modifying nocturnal thumbsucking.

REFERENCES

Garliner D. (1976) Myofunctional Therapy in Dental Practice. Saunders, Philadelphia.

Lassen M. and Fluent N. (1978) Elimination of nocturnal thumbsucking by glove wearing, J. Behav. Ther. & Exp. Psychiat. 9,85.

Rincover A. (1978) Sensory extinction: A procedure for eliminating self-stimulatory behavior in developmentally disabled children, J. Abnorm. Child Psychol. 6, 299- 310.

Rincover A., Cook R., Peoples A. and Packard D. (1979) Sensory extinction and sensory reinforcement principles for programming multiple adaptive behavior change, J. Appl. Behav. Anal. 12,221L233.

Ross J. (1975) Parents modify thumbsucking: A case study, J. Behav. Ther. & Exp. Psychiat. 6, 248-249.