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The behavioral treatment of elective mutism: Two case studies
J. Bch.
Then .ifip.
Psychia. Vd. 8. pp. 143-149.Rrslmcm Rem. 1977.PrintediaGremt B&aim
THE BEHAVIORAL TREATMENT OF ELECTIVE MUTISM: TWO CASE STUDIES*t DONALD A. WILLIAMSON,
Northeast
STEVE H. SANDERS, WILLIAM and DUNCAN WHITE Community
Mental
Health Center,
Memphis,
R. SEWELL,
JACK N. HANEY
TN 38134, U.S.A.
Summary-Two electively mute children were successfully treated using a variety of behavior therapy techniques, including two procedures which have never been applied to the treatment of elective mutism. i.e. reinforcement sampling and an escape procedure. The frequency of speaking in particular environments, e.g. at school. was increased for both cases. Follow-up information, gathered from one month to one year after treatment, was obtained. In all cases. the behavioral changes had been maintained or improved.
Elective mutism is a term which was first used by Tramer (1934) to describe the behavior of children who are “silent among all but a small circle of intimates.” Recently, this definition has been slightly refined so that it can be stated in more traditional behavioral terminology-persons who “speak only in restricted stimulus settings” (Wulbert, Nyman, Snow and Owen, 1973). This definition is an improvement over that proposed by Tramer because it explicitly states the operant, i.e. speaking, and makes a direct reference to differential responding in different stimulus conditions. Stimulus control refers to the extent to which the probability of a response is controlled by the presence or absence of a stimulus (Ferster and Pet-rot, 1968). Thus, in the language of behavioral psychologists, the verbal behavior of electively mute children is under strong stimulus control of one environmental setting, e.g. home, parents, family, etc. Reed (1963), after an extensive review of the literature, found treatment to have been unsuccessful and concluded that elective mutism is an intractable syndrome. However, since 1963, there have been a number of reported successful treatments of elective *Request for reprints should be 5515 Shelby Oaks Drive, Memphis, tithe authors are indebted to Ms. Calhoun without whose assistance,
mutism using behavior modification techniques. These techniques have included: shaping (Blake and Moss, 1967), stimulus fading alone (Conrad, Delk and Williams, 1974; Rasbury, 1974), stimulus fading and shaping in combination (Norman and Broman, 1970); and stimulus fading in combination with time out (Wulbert et al., 1973). The present article describes, in detail, the treatment of two elective mutes using a number of behavioral procedures as dictated by the changes in behavior and by the controlling stimuli. The use of a number of procedures was necessary because with a true elective mute it is difficult to find the single procedure which will produce the initial verbal response in the nonverbal environment. Follow-up data are provided and a strategy for treating the elective mute is suggested.
CASE I Method Background. Michael, an eight-year-old, had been referred for treatment due to his total lack of verbalization in the school setting. Despite his silence at school, his academic
addressed to William R. Sewell. Northeast Community Mental Health Center, TN 38134, U.S.A. Jackie Young. Ms. Lil Rovinsky, Ms. Irene Odor, Ms. Rene Nickel and Ms. Brenda this study could not have been completed. 143
131 DONALD A. WILLIAMSON.
STEVE H. SANDERS.
WILLIAM R. SEWELL. JACK N. HANEY
performance was relatively normal. At the time of referral, Michael was attending the third grade and had not emitted any verbal responses in school since his initial enrollment in the first grade. However, his mother reported that he spoke frequently at home. This assessment was supported by tape recordings of normal verbalization at home. Procedures and results This section is organized by presenting the figure, and describing the procedures and results for each stage of treatment. Figure 1 shows the percentages of responses across 30 sessions for baseline (session l), shaping with modeling (sessions 2-S), escape plus positive reinforcement (sessions 6-24). and shaping with fading (sessions 2.530). The top row of Fig. 1 lists from left to right the procedures used in treatment. Baseline. (Session 1) The first session was held in the clinic setting for the purpose of obtaining comparative baseline data. The child was placed in a room for one hour and asked to say various words and answer questions asked by a therapist or Michael’s mother. Michael did not respond (see Fig. 1, session 1). x0 85
I
2
3
4
,
andDUNCAN WHITE
Shaping with modeling. (Fig. 1, sessions 2-5) To initiate unvoiced motor approximation to procedure speaking, a shaping/modeling similar to that used by Blake and Moss (1967) and Nolan and Pence (1970) was employed during the next two-hour sessions. Michael was instructed to imitate everything the therapist did with his mouth. The response requirements for each approximation of speech are indicated in Fig. 1 (sessions 2-5). On session 2 imitation of blowing was reinforced with one cent. On sessions 3 and 4, saying “ah” was reinforced by one cent and a time-out was added so that when Michael did not respond the therapist removed all materials from the table and turned his back for two minutes. On session 5 the response requirement was changed from saying “ah” to saying and the magnitude of the reinforcer “cat” was increasd from one cent plus a toy to one dollar plus a toy. Michael responded 100% of the time by bloiving on session 2, 40% and 100% on sessions 3 and 4 by saying “ah”, and not at all on session5 when the response required was and the magnitude of the the word “cat” reinforcer was high, e.g. one dollar and a toy.
6 7 8 Se%lOnS
9 IO-2425 2627-2823
Fig. 1. The percentage of prompted verbal responses shaping/modeling. escape and positive reinforcement. shaping fading phases.
M
for and
THE BEHAVIORAL TREATMENT OF ELECTIVE MIJTISM
The escape plus positive procedure was begun in session
reinforcement 6.
Escape and positive reinforcement. (Fig. 1, sessions 6-24) An escape procedure was implemented during sessions 6-8 to facilitate the production of a one-word response. During each session, Michael was told that if he said the word “home” he would receive one dollar and be allowed to leave the clinic for a tenminute rest break with his mother. Following the rest break his mother would return him to the room. Upon his return the procedural sequence would begin again with the same instructions. If he failed to respond, the therapist left the room for 20 min. During this time, the child was left alone and was instructed to sit up straight in his chair and look at the wall in front of him. At the end of this 20-min period the therapist entered the room and began another two-minute period, asking Michael to say “home”. It was made clear to the child that he would not be allowed to leave the room until he responded and that a response would be immediately followed by escape and positive reward. The prompt, “say home,” was given several times during the two-minute period. At the end of each hour, Michael was allowed to go to the restroom and get a drink of water. The escape plus positive reinforcement procedure was effective in producing a change from 10% responding on session 6 to 100% responding with two experimenters present on session 9. Due to this success, the sessions were moved to the classroom. Two hour morning sessions were conducted daily. The escape plus positive reinforcement procedure that had been used in the clinic was now used in the classroom with the teacher and students present. The percent responses dropped to zero during the sessions (see Fig. 1, sessions 10-24). The data were averaged across these sessions. These data show classroom did not procedure began one-word response
that generalization to the occur. A shaping/fading on session 25. Since a had been initiated in the
145
clinic, a decision was made once again to try shaping a one-word response in the clinic by first modeling and reinforcing imitation and then by increasing the response requirements. This time, shaping was successful and stimulus fading was begun so that eventually Michael was asked to speak in his classroom in the presence of other children and his teacher. Shaping/Fading. (Fig. 1, sessions 25-30) This was a shaping/fading procedure, as the response requirement continuously increased and the number of persons present was progressively increased and the physical environment was changed from the clinic to Michael’s classroom. During these sessions, the verbal responding was maintained by a contingency management program, while the response requirements and stimulus conditions were gradually changed. In sessions 25 and 26, pictures were presented to Michael, and he was asked “what is this picture”: the correct answer was modeled, and he was reinforced with social praise and a penny. Then, he was instructed to repeat the answer. On sessions 27 and 28 the modeled answer and prompt were dropped, on sessions 29 the experimenters were included in the session, and on session 30 Michael was asked the questions in front of the entire class. Michael was replying to a prompt 100% of the time on session 26. On sessions 27 and 28 Michael responded to 100% of the prompts and on 29 and 30 to 100% of the questions without a prompt. Follow-up. To insure continuation of speech, two-week and one-year reports were obtained from Michael’s teachers. These reports were obtained by interviews rather than direct classroom observation. A two-week follow-up report from Michael’s teacher indicated that he was speaking “normally” in class and on one occasion had even recited to the entire class. The follow-up after one year showed that Michael had continued to improve. His new teacher indicated that he always responded to questions from her or others and occasionally spoke spontaneously in class.
116 DONALD A. WILLIAMSON.
STEVE H. SANDERS,
WILLIAM R. SEWELL.
CASE II Method Background. Crissy, a seven-year-old girl of average intelligence had not spoken outside the house since kindergarten. Both parents submitted that speech was normal at home and that she even answered the telephone. When brought to the clinic for intake testing, Crissy responded with withdrawn silence and shedding of tears following her father’s reprimands. Procedures and results This section is organized by presenting the figure and describing the procedures and results for each stage. Figure 2 shows the percentage of responses across one session for baseline (session 1); (sessions 2-11); modeling shaping with
JACK N. HANEY and DUNCAN WHITE
reinforcement with stimulus fading (sessions 12-16); reinforcement with fading and reinforcer sampling (sessions 17-21); reinforcement with reinforcement fading (sessions 22-38); and a one-month follow-up with no reinforcement (sessions 39-41). The top row lists the procedures used in treatment. Listed under each treatment heading is the response required during shaping and modeling or the persons present and/or the reinforcer during the remaining phases. Baseline. The first session was devoted to taking a baseline measurement of talking in the clinic setting. To achieve consistency in discriminative stimuli for speaking, a list of 80 words was used as prompts for talking. The therapist informed Crissy that she was to repeat after him each word on the list. The therapist then pointed to and read each word
Fig. 2. The percentage of prompted verbal responses for Case II during shaping/modeling; reinforcement, reinforcer sampling; reinforcement stimulus fading, and follow-up fading: reinforcement/reinforcement phases.
THE BEHAVIORAL TREATMENT OF ELECTIVE MUTISM
for her response. A one-minute rest period followed each 80 words. Crissy was allowed to walk about the room, get a drink of water, or go to the restroom during each rest period. The data for session 1 on Fig. 2 show that Crissy did not respond to any prompt. Shaping/Modeling. (Fig. 2, sessions 2-11) During sessions 2-11, an attempt was made to initiate both unvoiced and voiced approximations to speaking. The therapist first i.e. modeled motor approximations, eye contact and blowing, and finally a voiced response. Imitative responses were “mmm” continuously reinforced during sessions 2-4, with one cent per response. This reinforcement schedule was changed to a fixed ratio 10 (FRlO) schedule, with 10 cents given per 10 responses for the remaining sessions in the clinic. As can be seen in Fig. 2 (sessions 2-ll), Crissy always imitated the eye contact and blowing responses after treatment began. However, she never imitated the sound “mmm.” Reinforcement and reinforcer sampling with stimulus fading. To achieve voiced response initiation and generalization to others via positive reinforcement, Crissy’s mother was used as a model in conjunction with a stimulus fading procedure during sessions 12-20. On session 12, Crissy’s mother followed the same word list modeling procedure used by the therapist to gather baseline, with an FRlO for ten cents employed. Shaping and, stimulus fading were used from sessions 13-16 and the same reinforcement schedule was used. However, shaping was begun on session 13. On session 13, the response requirement changed so that a question requiring more than a one-word answer was substituted for every fifth word in the list. In addition, stimulus fading was begun by stationing experimenter one (El) in the far comer of the room. Crissy did not respond on session 13. Therefore, on session 14 questions were still substituted for every fifth word, but El did not enter the room. Cri~sy responded 100% of the time on session 14. On session 15, shaping continued by
147
substituting questions for every fourth word, and stimulus fading was reinstituted by stationing El in the doorway. In this location El was completely visible but farther away than on previous sessions. Crissy did not respond on session 15. On session 16, the stimulus material remained the same, but the door was partially closed, making El partially visible. Crissy responded 100% of the time. On session 17 a reinforcer sampling procedure similar to that described by Ayllon and Azrin (1968) was added to produce a response in the presence of a “stranger.” More specifically, a pair of expensive championship roller skates were placed on the table before her and she was told that she could take them home and use them for three days if she responded to all prompts from El. Then she was told that she would own the roller skates if, on session 21, she read for ten minutes to her class. The stimulus materials were the same and El was stationed in the doorway. Crissy had not responded earlier when El was completely visible in the door. However, on session 17 wth the reinforcer sampling procedure, Crissy responded 100% of the time and took the skates home for three days. On session 18. the stimulus materials were the same, but E2 was at the table with Crissy. She did not respond. On session 19, El was at the table and she responded 100% of the time. On session 20, E2 was slightly visible with the door ajar and Crissy did not respond. The reinforcer sampling procedure was not strong enough to produce generalization to a second “stranger” who was not included in the reinforcement contingency. Session 21 was conducted at Crissy’s school. Crissy was instructed that she could have complete possession of the roller skates by reading a passage from a book for ten minutes to her class. The immediate possibility of obtaining the reinforcer produced generalization. Crissy read the entire passage in front of the class and earned the roller skates. Reinforcement and reinforcement fading. During this phase, the emphasis was on fading the material reinforcer so that only natural
148 DONALD A. WLLIAMSOlri.
STEVE H. SANDERS.
WILLIAM R. SEWELL.
contingencies remained at the end of our intervention. For all sessions the response requirement was reading a passage to the class Crissy was given several and teacher. opportunities a day to read a passage to the class. On sessions 22-24, she could earn 51.00 for all readings. She responded to 100% of the requests. On sessions 25-30, she earned S1.00 for all reading plus a card. She and the class were told that on the day five cards were earned the class would have a party. Crissy responded to 80% of the requests and did not earn a card on session 25, did earn cards on sessions 26-29 by re-ponding to 100% of the requests, did not on session 30. Finally, on session 31, she did respond to all requests and the entire class had a party. On sessions 32-38, the response requirement remained the same, but Crissy only earned S.25 for responding to all requests; the requests were doubled and it took seven cards to earn a party for the class. Crissy responded to 100% of the requests and the class earned a party. Follow-up, As with Case I, one month after termination, Crissy’s teacher was contacted to insure continuation of verbal behavior in the school setting. The prompts to read were reintroduced for three sessions. Figure 2 (sessions 39-41) shows Crissy was responding to 100% of the requests without receiving reinforcement. She was also responding freely in all of her classes. A one-year follow-up was not possible because the family moved to another city without leaving a new address. DISCUSSION Two cases of elective mutism were successfully treated by sequentially applying behavior modification techniques. Short- and long-term follow-up data suggest that once mutism in one environment was corrected, naturally occurring social reinforcers maintained the verbal behavior. This finding was similar to that of Nolan and Pence (1970) and Rasbury (1974). An analysis of the results of these two cases in combination with those of other case reports
JACK N. HANEY and DUNCAN WHITE
suggest a working strategy for the behavioral treatment of elective mutism. The first step, and probably most important, is to empirically determine under what environment conditions the child will speak, even if the frequency is low. If the child is speaking to most persons in the test environments but at a low frequency, then the problem is really one of reluctant speech and contingency management procedures should be used to increase this frequency in the appropriate environments. (Straugh, Potter and Hamilton, 1965) If the child speaks to only a few people, e.g. the mother, but not to others in a test environment, then stimulus fading procedures should be used to bring the child’s verbal behavior gradually under the control of new persons. (Conrad er al., 1974; Rasbury, 1974). Finally. if the child does not talk in the presence of anyone in a particular test environment, then the therapist can either shape the child’s verbal behavior (Blake and Moss, 1967), employ an avoidance procedure (Van der Kooy and Webseter, 1975), use reinforcer sampling with a high magnitude reinforcer (Case II), or utilize an escape/positive reinforcement technique as was used for Case I. Following initiation of one or more word -responses, “strangers” can be faded in while the child is speaking. Once speech is stable in the presence of the “strangers,” the therapist can change the environment to the original setting for not talking and continue. The first option, shaping, was not successful for either of the t\vo cases presented in this report. The second choice, an avoidance procedure presented by Van der Kooy and Webster (1975). was successful for one case and a reinforcer sampling procedure was successful for the second case of this report. Also, the escape/ positive reinforcement technique was successfully used for Case 1. The fadin procedure has been effectively used by Conrad et al. (1974). The utility of this treatment strategy is currently being tested with a number of cases. The most prevalent request by investigators, program administrators, and, in fact, legislators is for follow-up data substantiating
THE BEHAVIORAL
TREATMENT
permanence of the treatment effect. This study definitely meets this need and is substantially strengthened by the follow-up data provided.
REFERENCES Ayllon T. and Azrin N. (1968) The token economy: A Motivational System for Therapy and Rehabilitation. Appleton-Century-Crofts, New York. Blake P. and Moss T. (1967) The development of socialization skills in an electively mute child, Behav. Res. & Ther. 5.349-3.56. Conrad R. D., Delk J. L. and Williams D. (1974) Use of stimulus fading procedures in the treatment of situation specific mutism: A case study, J. Behav. Ther. 8 Exp. Psychiat. 5. 99-100. Ferster C. B. and Perrot M. C. (1968) Behavior Principles. Appleton-Century-Crofts, New York. Nolan J. D. and Pence C. (1970) Operant conditioning principles in the treatment of a selectively mute child,
OF ELECTIVE MUTISM
149
3. Consult. Clin. Psych. 35,265268. Norman A. and Broman H. J. (1970) Volume feedback and generalization technique in shaping speech of an electivelv mute boy: A case study, Perceptual Motor Skills 31; 463-470. _ Rasbury W. C. (1975) Behavioral treatment of selective mutism: A case report, J. Behav. Ther. 8 Exp. Psychiat. 5,103.104. Reed G. R. (1963) Elective mutism in children: A reappraisal. J. Child Psych. Psychiat. Straughn J. H.. Potter W. and Hamilton S. M. (1965) The behavioral treatment of an elective mute, J. Child Psych. Psychiat. 6.125130. Tramer M. (1963) Elektiver mutismus bei ltmdem. Z. Kinderpsychiat., 1934, 1. 30-35. (Cited by Reed, G. R.) J. Child Psych. Psychiat. 4,99, Van der Kooy D. and Webster C. D. (1975) J. Behav. Ther. & Exp. Psychiat. 6, 149-152. Wulbert M., Nyman 8. A., Snow D. and Owen Y. (1973) The efficacy of stimulus fading in the treatment of elective mutism: A case study, J. appl. Behav. Anal. 6. 435-441.
Then .ifip.
Psychia. Vd. 8. pp. 143-149.Rrslmcm Rem. 1977.PrintediaGremt B&aim
THE BEHAVIORAL TREATMENT OF ELECTIVE MUTISM: TWO CASE STUDIES*t DONALD A. WILLIAMSON,
Northeast
STEVE H. SANDERS, WILLIAM and DUNCAN WHITE Community
Mental
Health Center,
Memphis,
R. SEWELL,
JACK N. HANEY
TN 38134, U.S.A.
Summary-Two electively mute children were successfully treated using a variety of behavior therapy techniques, including two procedures which have never been applied to the treatment of elective mutism. i.e. reinforcement sampling and an escape procedure. The frequency of speaking in particular environments, e.g. at school. was increased for both cases. Follow-up information, gathered from one month to one year after treatment, was obtained. In all cases. the behavioral changes had been maintained or improved.
Elective mutism is a term which was first used by Tramer (1934) to describe the behavior of children who are “silent among all but a small circle of intimates.” Recently, this definition has been slightly refined so that it can be stated in more traditional behavioral terminology-persons who “speak only in restricted stimulus settings” (Wulbert, Nyman, Snow and Owen, 1973). This definition is an improvement over that proposed by Tramer because it explicitly states the operant, i.e. speaking, and makes a direct reference to differential responding in different stimulus conditions. Stimulus control refers to the extent to which the probability of a response is controlled by the presence or absence of a stimulus (Ferster and Pet-rot, 1968). Thus, in the language of behavioral psychologists, the verbal behavior of electively mute children is under strong stimulus control of one environmental setting, e.g. home, parents, family, etc. Reed (1963), after an extensive review of the literature, found treatment to have been unsuccessful and concluded that elective mutism is an intractable syndrome. However, since 1963, there have been a number of reported successful treatments of elective *Request for reprints should be 5515 Shelby Oaks Drive, Memphis, tithe authors are indebted to Ms. Calhoun without whose assistance,
mutism using behavior modification techniques. These techniques have included: shaping (Blake and Moss, 1967), stimulus fading alone (Conrad, Delk and Williams, 1974; Rasbury, 1974), stimulus fading and shaping in combination (Norman and Broman, 1970); and stimulus fading in combination with time out (Wulbert et al., 1973). The present article describes, in detail, the treatment of two elective mutes using a number of behavioral procedures as dictated by the changes in behavior and by the controlling stimuli. The use of a number of procedures was necessary because with a true elective mute it is difficult to find the single procedure which will produce the initial verbal response in the nonverbal environment. Follow-up data are provided and a strategy for treating the elective mute is suggested.
CASE I Method Background. Michael, an eight-year-old, had been referred for treatment due to his total lack of verbalization in the school setting. Despite his silence at school, his academic
addressed to William R. Sewell. Northeast Community Mental Health Center, TN 38134, U.S.A. Jackie Young. Ms. Lil Rovinsky, Ms. Irene Odor, Ms. Rene Nickel and Ms. Brenda this study could not have been completed. 143
131 DONALD A. WILLIAMSON.
STEVE H. SANDERS.
WILLIAM R. SEWELL. JACK N. HANEY
performance was relatively normal. At the time of referral, Michael was attending the third grade and had not emitted any verbal responses in school since his initial enrollment in the first grade. However, his mother reported that he spoke frequently at home. This assessment was supported by tape recordings of normal verbalization at home. Procedures and results This section is organized by presenting the figure, and describing the procedures and results for each stage of treatment. Figure 1 shows the percentages of responses across 30 sessions for baseline (session l), shaping with modeling (sessions 2-S), escape plus positive reinforcement (sessions 6-24). and shaping with fading (sessions 2.530). The top row of Fig. 1 lists from left to right the procedures used in treatment. Baseline. (Session 1) The first session was held in the clinic setting for the purpose of obtaining comparative baseline data. The child was placed in a room for one hour and asked to say various words and answer questions asked by a therapist or Michael’s mother. Michael did not respond (see Fig. 1, session 1). x0 85
I
2
3
4
,
andDUNCAN WHITE
Shaping with modeling. (Fig. 1, sessions 2-5) To initiate unvoiced motor approximation to procedure speaking, a shaping/modeling similar to that used by Blake and Moss (1967) and Nolan and Pence (1970) was employed during the next two-hour sessions. Michael was instructed to imitate everything the therapist did with his mouth. The response requirements for each approximation of speech are indicated in Fig. 1 (sessions 2-5). On session 2 imitation of blowing was reinforced with one cent. On sessions 3 and 4, saying “ah” was reinforced by one cent and a time-out was added so that when Michael did not respond the therapist removed all materials from the table and turned his back for two minutes. On session 5 the response requirement was changed from saying “ah” to saying and the magnitude of the reinforcer “cat” was increasd from one cent plus a toy to one dollar plus a toy. Michael responded 100% of the time by bloiving on session 2, 40% and 100% on sessions 3 and 4 by saying “ah”, and not at all on session5 when the response required was and the magnitude of the the word “cat” reinforcer was high, e.g. one dollar and a toy.
6 7 8 Se%lOnS
9 IO-2425 2627-2823
Fig. 1. The percentage of prompted verbal responses shaping/modeling. escape and positive reinforcement. shaping fading phases.
M
for and
THE BEHAVIORAL TREATMENT OF ELECTIVE MIJTISM
The escape plus positive procedure was begun in session
reinforcement 6.
Escape and positive reinforcement. (Fig. 1, sessions 6-24) An escape procedure was implemented during sessions 6-8 to facilitate the production of a one-word response. During each session, Michael was told that if he said the word “home” he would receive one dollar and be allowed to leave the clinic for a tenminute rest break with his mother. Following the rest break his mother would return him to the room. Upon his return the procedural sequence would begin again with the same instructions. If he failed to respond, the therapist left the room for 20 min. During this time, the child was left alone and was instructed to sit up straight in his chair and look at the wall in front of him. At the end of this 20-min period the therapist entered the room and began another two-minute period, asking Michael to say “home”. It was made clear to the child that he would not be allowed to leave the room until he responded and that a response would be immediately followed by escape and positive reward. The prompt, “say home,” was given several times during the two-minute period. At the end of each hour, Michael was allowed to go to the restroom and get a drink of water. The escape plus positive reinforcement procedure was effective in producing a change from 10% responding on session 6 to 100% responding with two experimenters present on session 9. Due to this success, the sessions were moved to the classroom. Two hour morning sessions were conducted daily. The escape plus positive reinforcement procedure that had been used in the clinic was now used in the classroom with the teacher and students present. The percent responses dropped to zero during the sessions (see Fig. 1, sessions 10-24). The data were averaged across these sessions. These data show classroom did not procedure began one-word response
that generalization to the occur. A shaping/fading on session 25. Since a had been initiated in the
145
clinic, a decision was made once again to try shaping a one-word response in the clinic by first modeling and reinforcing imitation and then by increasing the response requirements. This time, shaping was successful and stimulus fading was begun so that eventually Michael was asked to speak in his classroom in the presence of other children and his teacher. Shaping/Fading. (Fig. 1, sessions 25-30) This was a shaping/fading procedure, as the response requirement continuously increased and the number of persons present was progressively increased and the physical environment was changed from the clinic to Michael’s classroom. During these sessions, the verbal responding was maintained by a contingency management program, while the response requirements and stimulus conditions were gradually changed. In sessions 25 and 26, pictures were presented to Michael, and he was asked “what is this picture”: the correct answer was modeled, and he was reinforced with social praise and a penny. Then, he was instructed to repeat the answer. On sessions 27 and 28 the modeled answer and prompt were dropped, on sessions 29 the experimenters were included in the session, and on session 30 Michael was asked the questions in front of the entire class. Michael was replying to a prompt 100% of the time on session 26. On sessions 27 and 28 Michael responded to 100% of the prompts and on 29 and 30 to 100% of the questions without a prompt. Follow-up. To insure continuation of speech, two-week and one-year reports were obtained from Michael’s teachers. These reports were obtained by interviews rather than direct classroom observation. A two-week follow-up report from Michael’s teacher indicated that he was speaking “normally” in class and on one occasion had even recited to the entire class. The follow-up after one year showed that Michael had continued to improve. His new teacher indicated that he always responded to questions from her or others and occasionally spoke spontaneously in class.
116 DONALD A. WILLIAMSON.
STEVE H. SANDERS,
WILLIAM R. SEWELL.
CASE II Method Background. Crissy, a seven-year-old girl of average intelligence had not spoken outside the house since kindergarten. Both parents submitted that speech was normal at home and that she even answered the telephone. When brought to the clinic for intake testing, Crissy responded with withdrawn silence and shedding of tears following her father’s reprimands. Procedures and results This section is organized by presenting the figure and describing the procedures and results for each stage. Figure 2 shows the percentage of responses across one session for baseline (session 1); (sessions 2-11); modeling shaping with
JACK N. HANEY and DUNCAN WHITE
reinforcement with stimulus fading (sessions 12-16); reinforcement with fading and reinforcer sampling (sessions 17-21); reinforcement with reinforcement fading (sessions 22-38); and a one-month follow-up with no reinforcement (sessions 39-41). The top row lists the procedures used in treatment. Listed under each treatment heading is the response required during shaping and modeling or the persons present and/or the reinforcer during the remaining phases. Baseline. The first session was devoted to taking a baseline measurement of talking in the clinic setting. To achieve consistency in discriminative stimuli for speaking, a list of 80 words was used as prompts for talking. The therapist informed Crissy that she was to repeat after him each word on the list. The therapist then pointed to and read each word
Fig. 2. The percentage of prompted verbal responses for Case II during shaping/modeling; reinforcement, reinforcer sampling; reinforcement stimulus fading, and follow-up fading: reinforcement/reinforcement phases.
THE BEHAVIORAL TREATMENT OF ELECTIVE MUTISM
for her response. A one-minute rest period followed each 80 words. Crissy was allowed to walk about the room, get a drink of water, or go to the restroom during each rest period. The data for session 1 on Fig. 2 show that Crissy did not respond to any prompt. Shaping/Modeling. (Fig. 2, sessions 2-11) During sessions 2-11, an attempt was made to initiate both unvoiced and voiced approximations to speaking. The therapist first i.e. modeled motor approximations, eye contact and blowing, and finally a voiced response. Imitative responses were “mmm” continuously reinforced during sessions 2-4, with one cent per response. This reinforcement schedule was changed to a fixed ratio 10 (FRlO) schedule, with 10 cents given per 10 responses for the remaining sessions in the clinic. As can be seen in Fig. 2 (sessions 2-ll), Crissy always imitated the eye contact and blowing responses after treatment began. However, she never imitated the sound “mmm.” Reinforcement and reinforcer sampling with stimulus fading. To achieve voiced response initiation and generalization to others via positive reinforcement, Crissy’s mother was used as a model in conjunction with a stimulus fading procedure during sessions 12-20. On session 12, Crissy’s mother followed the same word list modeling procedure used by the therapist to gather baseline, with an FRlO for ten cents employed. Shaping and, stimulus fading were used from sessions 13-16 and the same reinforcement schedule was used. However, shaping was begun on session 13. On session 13, the response requirement changed so that a question requiring more than a one-word answer was substituted for every fifth word in the list. In addition, stimulus fading was begun by stationing experimenter one (El) in the far comer of the room. Crissy did not respond on session 13. Therefore, on session 14 questions were still substituted for every fifth word, but El did not enter the room. Cri~sy responded 100% of the time on session 14. On session 15, shaping continued by
147
substituting questions for every fourth word, and stimulus fading was reinstituted by stationing El in the doorway. In this location El was completely visible but farther away than on previous sessions. Crissy did not respond on session 15. On session 16, the stimulus material remained the same, but the door was partially closed, making El partially visible. Crissy responded 100% of the time. On session 17 a reinforcer sampling procedure similar to that described by Ayllon and Azrin (1968) was added to produce a response in the presence of a “stranger.” More specifically, a pair of expensive championship roller skates were placed on the table before her and she was told that she could take them home and use them for three days if she responded to all prompts from El. Then she was told that she would own the roller skates if, on session 21, she read for ten minutes to her class. The stimulus materials were the same and El was stationed in the doorway. Crissy had not responded earlier when El was completely visible in the door. However, on session 17 wth the reinforcer sampling procedure, Crissy responded 100% of the time and took the skates home for three days. On session 18. the stimulus materials were the same, but E2 was at the table with Crissy. She did not respond. On session 19, El was at the table and she responded 100% of the time. On session 20, E2 was slightly visible with the door ajar and Crissy did not respond. The reinforcer sampling procedure was not strong enough to produce generalization to a second “stranger” who was not included in the reinforcement contingency. Session 21 was conducted at Crissy’s school. Crissy was instructed that she could have complete possession of the roller skates by reading a passage from a book for ten minutes to her class. The immediate possibility of obtaining the reinforcer produced generalization. Crissy read the entire passage in front of the class and earned the roller skates. Reinforcement and reinforcement fading. During this phase, the emphasis was on fading the material reinforcer so that only natural
148 DONALD A. WLLIAMSOlri.
STEVE H. SANDERS.
WILLIAM R. SEWELL.
contingencies remained at the end of our intervention. For all sessions the response requirement was reading a passage to the class Crissy was given several and teacher. opportunities a day to read a passage to the class. On sessions 22-24, she could earn 51.00 for all readings. She responded to 100% of the requests. On sessions 25-30, she earned S1.00 for all reading plus a card. She and the class were told that on the day five cards were earned the class would have a party. Crissy responded to 80% of the requests and did not earn a card on session 25, did earn cards on sessions 26-29 by re-ponding to 100% of the requests, did not on session 30. Finally, on session 31, she did respond to all requests and the entire class had a party. On sessions 32-38, the response requirement remained the same, but Crissy only earned S.25 for responding to all requests; the requests were doubled and it took seven cards to earn a party for the class. Crissy responded to 100% of the requests and the class earned a party. Follow-up, As with Case I, one month after termination, Crissy’s teacher was contacted to insure continuation of verbal behavior in the school setting. The prompts to read were reintroduced for three sessions. Figure 2 (sessions 39-41) shows Crissy was responding to 100% of the requests without receiving reinforcement. She was also responding freely in all of her classes. A one-year follow-up was not possible because the family moved to another city without leaving a new address. DISCUSSION Two cases of elective mutism were successfully treated by sequentially applying behavior modification techniques. Short- and long-term follow-up data suggest that once mutism in one environment was corrected, naturally occurring social reinforcers maintained the verbal behavior. This finding was similar to that of Nolan and Pence (1970) and Rasbury (1974). An analysis of the results of these two cases in combination with those of other case reports
JACK N. HANEY and DUNCAN WHITE
suggest a working strategy for the behavioral treatment of elective mutism. The first step, and probably most important, is to empirically determine under what environment conditions the child will speak, even if the frequency is low. If the child is speaking to most persons in the test environments but at a low frequency, then the problem is really one of reluctant speech and contingency management procedures should be used to increase this frequency in the appropriate environments. (Straugh, Potter and Hamilton, 1965) If the child speaks to only a few people, e.g. the mother, but not to others in a test environment, then stimulus fading procedures should be used to bring the child’s verbal behavior gradually under the control of new persons. (Conrad er al., 1974; Rasbury, 1974). Finally. if the child does not talk in the presence of anyone in a particular test environment, then the therapist can either shape the child’s verbal behavior (Blake and Moss, 1967), employ an avoidance procedure (Van der Kooy and Webseter, 1975), use reinforcer sampling with a high magnitude reinforcer (Case II), or utilize an escape/positive reinforcement technique as was used for Case I. Following initiation of one or more word -responses, “strangers” can be faded in while the child is speaking. Once speech is stable in the presence of the “strangers,” the therapist can change the environment to the original setting for not talking and continue. The first option, shaping, was not successful for either of the t\vo cases presented in this report. The second choice, an avoidance procedure presented by Van der Kooy and Webster (1975). was successful for one case and a reinforcer sampling procedure was successful for the second case of this report. Also, the escape/ positive reinforcement technique was successfully used for Case 1. The fadin procedure has been effectively used by Conrad et al. (1974). The utility of this treatment strategy is currently being tested with a number of cases. The most prevalent request by investigators, program administrators, and, in fact, legislators is for follow-up data substantiating
THE BEHAVIORAL
TREATMENT
permanence of the treatment effect. This study definitely meets this need and is substantially strengthened by the follow-up data provided.
REFERENCES Ayllon T. and Azrin N. (1968) The token economy: A Motivational System for Therapy and Rehabilitation. Appleton-Century-Crofts, New York. Blake P. and Moss T. (1967) The development of socialization skills in an electively mute child, Behav. Res. & Ther. 5.349-3.56. Conrad R. D., Delk J. L. and Williams D. (1974) Use of stimulus fading procedures in the treatment of situation specific mutism: A case study, J. Behav. Ther. 8 Exp. Psychiat. 5. 99-100. Ferster C. B. and Perrot M. C. (1968) Behavior Principles. Appleton-Century-Crofts, New York. Nolan J. D. and Pence C. (1970) Operant conditioning principles in the treatment of a selectively mute child,
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3. Consult. Clin. Psych. 35,265268. Norman A. and Broman H. J. (1970) Volume feedback and generalization technique in shaping speech of an electivelv mute boy: A case study, Perceptual Motor Skills 31; 463-470. _ Rasbury W. C. (1975) Behavioral treatment of selective mutism: A case report, J. Behav. Ther. 8 Exp. Psychiat. 5,103.104. Reed G. R. (1963) Elective mutism in children: A reappraisal. J. Child Psych. Psychiat. Straughn J. H.. Potter W. and Hamilton S. M. (1965) The behavioral treatment of an elective mute, J. Child Psych. Psychiat. 6.125130. Tramer M. (1963) Elektiver mutismus bei ltmdem. Z. Kinderpsychiat., 1934, 1. 30-35. (Cited by Reed, G. R.) J. Child Psych. Psychiat. 4,99, Van der Kooy D. and Webster C. D. (1975) J. Behav. Ther. & Exp. Psychiat. 6, 149-152. Wulbert M., Nyman 8. A., Snow D. and Owen Y. (1973) The efficacy of stimulus fading in the treatment of elective mutism: A case study, J. appl. Behav. Anal. 6. 435-441.