- Email: [email protected]
spastic behavior via a microswitch-based program
Research in Developmental Disabilities 30 (2009) 378–385
Contents lists available at ScienceDirect
Research in Developmental Disabilities
Two boys with multiple disabilities increasing adaptive responding and curbing dystonic/spastic behavior via a microswitch-based program Giulio E. Lancioni a,*, Nirbhay N. Singh b, Mark F. O’Reilly c, Jeff Sigafoos d, Robert Didden e, Doretta Oliva f a
Department of Psychology, University of Bari, Via Quintino Sella 268, 70100 Bari, Italy ONE Research Institute, Midlothian, VA, USA c University of Texas at Austin, Austin, TX, USA d Victoria University of Wellington, Wellington, New Zealand e Radboud University Nijmegen, Nijmegen, The Netherlands f Lega F. D’Oro Research Center, Osimo (AN), Italy b
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 14 July 2008 Received 6 July 2008
A recent study has shown that microswitch clusters (i.e., combinations of microswitches) and contingent stimulation could be used to increase adaptive responding and reduce dystonic/spastic behavior in two children with multiple disabilities [Lancioni, G. E., Singh, N. N., Oliva, D., Scalini, L., & Groeneweg, J. (2003). Microswitch clusters to enhance non-spastic response schemes with students with multiple disabilities. Disability and Rehabilitation, 25, 301–304]. The present study was an attempt to replicate the aforementioned study with two boys with multiple disabilities. The adaptive responses selected for the boys consisted of pushing an object with the hand or the back. The dystonic/spastic behavior consisted of body arching (i.e., pushing belly and stomach forward) and leg stretching for the two boys, respectively. Initially, the boys received preferred stimulation for all hand- and back-pushing responses. Subsequently, the stimulation followed only the responses that occurred free from the dystonic/spastic behavior. The results showed that both boys increased the frequency of adaptive responses, learned to perform these responses free from the dystonic/spastic behavior, and maintained this improved performance during a 2-month post-intervention check. ß 2008 Elsevier Ltd. All rights reserved.
Keywords: Adaptive responses Dystonic behavior Microswitch clusters Multiple disabilities
* Corresponding author. E-mail address: [email protected] (G.E. Lancioni). 0891-4222/$ – see front matter ß 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.ridd.2008.07.005
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1. Introduction Persons with profound and multiple disabilities may have very low levels of adaptive responding with limited opportunities of advancing in their development and increasing their control over the environment (Gutowski, 1996; Holburn, Nguyen, & Vietze, 2004; Mechling, 2006; Murphy, Saunders, Saunders, & Olswang, 2004). Frequently, they may also present with forms of problem behavior, such as (a) inadequate body postures (e.g., forward head tilting), (b) stereotypies (e.g., hand mouthing and eye poking), and (c) dystonic/spastic behavior (e.g., back arching or leg stretching), occurring concomitant with adaptive responses and independent of them (Lancioni, Singh, Oliva, Scalini, & Groeneweg, 2003; Lancioni et al., 2008b,c; Luiselli, 1998; Saloviita & Pennanen, 2003). Educational intervention with these persons needs to encompass the dual goal of promoting adaptive responding and reducing problem behavior in order to advance their situation in a meaningful and harmonious manner (Lancioni et al., 2007a, 2008b). A form of educational intervention recently put forward to pursue such a dual goal relies on programs involving microswitch clusters (i.e., combinations of microswitches) that concurrently monitor adaptive responding and problem behavior (Lancioni et al., 2006, 2008a). Initially, these programs provide preferred stimulation for all adaptive responses irrespective of whether they occur free or in combination with the problem behavior. Once adaptive responding has increased, the programs provide preferred stimulation only for the adaptive responses that occur free from the problem behavior (Lancioni et al., 2006). For example, a microswitch cluster monitoring adaptive vocalization responses and eye poking may ensure that (a) initially, all vocalization responses are followed by positive stimulation and (b) subsequently, only vocalization responses performed in the absence of eye poking are followed by positive stimulation (Lancioni et al., 2007b). Programs with microswitch clusters have been mainly addressed to increase adaptive hand and foot responses and reduce inappropriate head position or hand/finger mouthing and eye poking (Lancioni et al., 2008a). Only one study has been reported in which microswitch clusters were used to increase adaptive responses and reduce dystonic/spastic behavior (Lancioni et al., 2003). The positive results of this study with the two participants of 9 and 14 years of age seem to indicate (a) the possibility of supplementing traditional, therapist-directed physiotherapy with the exercise of selfdirected motor control, and thus (b) the availability of an additional, personalized strategy to improve and sustain the participant’s motor condition. In light of the apparent relevance of this last type of program and the limited evidence available about it, replication efforts would seem to be warranted. The purpose of the present study was to carry out such a replication with two boys with multiple disabilities. The adaptive responses selected for the boys consisted of pushing an object with the hand or the back. The dystonic/ spastic behavior consisted of body arching (i.e., pushing belly and stomach forward) and leg stretching. 2. Method 2.1. Participants The participants, Clint and Gene, were 4.1 and 13.4 years of age, respectively, and were rated in the severe/profound range of intellectual disability, although no IQ scores were available. They had congenital encephalopathy, spastic tetraparesis with dystonic movements, scoliosis, minimal residual vision or total blindness, and lack of speech. Clint, who was born prematurely with very low birth weight and suffered from perinatal hypoxia, was also diagnosed with epilepsy. This was largely controlled through medication. Gene had been involved in microswitch programs aimed at increasing adaptive responding. Those programs were partially active when this study started. Both participants spent their time in a wheelchair or in bed. They lived at home with their parents and attended daily educational programs focusing almost exclusively on physiotherapy and general stimulation. Parents and teachers had provided informed consent for this study.
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2.2. Adaptive responses, problem behavior, and microswitch clusters The adaptive responses consisted of pushing/pressing an object with the right hand (Clint) or with the upper part of the torso’s back (Gene). The objects were flexible, plastic cylinders placed on the participant’s leg (Clint) or on the wheelchair’s upper backrest area (Gene). In both cases, the cylinders were attached to a pressure microswitch, which was activated as the boy pushed on the cylinder. The problem (dystonic/spastic) behavior was body arching, that is, pushing belly and stomach forward (Clint) or stretching one or both legs forward (Gene). The microswitch clusters consisted of a combination of the pressure microswitch for the handpushing response with a pressure microswitch on the wheelchair’s lower backrest area for body arching (Clint) or the pressure microswitch for the back-pushing response and tilt microswitches at the boy’s ankles for leg stretching (Gene). The microswitch on the wheelchair’s lower backrest area would be activated when released from pressure (i.e., when Clint arched his body). The tilt microswitches at Gene’s ankles would be activated when Gene stretched one or both legs forward. 2.3. Control system, data collection, and preferred stimuli The microswitch clusters were connected to a battery-powered, electronic control system that served to (a) turn on preferred stimuli contingent on the hand- or back-pushing responses (i.e., according to the procedural conditions described below) and (b) record the data. The data were recorded via special counters linked to the system. The recording concerned (a) the frequency of the hand- or back-pushing responses per session, (b) the frequency of these responses performed in the absence of the problem behavior (i.e., correct responses), (c) the length of time that the problem behavior remained absent during the stimulation period following each response or each correct response through the different intervention sessions (see below), and (d) the amount of session time that was free from the problem behavior. Preferred stimuli were selected through a stimulus preference screening (Crawford & Schuster, 1993). The screening covered multiple stimuli; each stimulus was presented 15–40 nonconsecutive times. Only the stimuli that were followed by positive reactions from the boys (i.e., alerting, orienting, and/or smiling) in two-thirds of the presentations or more were selected for the study. Such stimuli included various types of music, recordings of familiar persons’ speech and non-speech sounds, various noises and songs, and vibratory inputs. 2.4. Experimental conditions The study was carried out according to an ABB1AB1 design in which A represented the baseline, B represented the intervention focusing on the hand- and back-pushing responses for the two boys, respectively, and B1 represented the intervention focusing on these responses and the problem behavior together (Barlow, Nock, & Hersen, 2008). At the start of the first B1 (scheduled after different lengths of the B for the two boys), a set of five sessions occurred, which included 2–5 instances of physical guidance by a research assistant to promote the absence of the problem behavior during hand- and back-pushing responses. To control for the overall impact of these sessions, matching guidance sessions were also used during the B phase (see below). A post-intervention check occurred 2 months after the second B1. The boys received 5–14 5-min sessions a day, depending on their availability. 2.4.1. Baseline (A phases) The two baseline phases included 8 and 11 sessions for Clint and 12 sessions for Gene. The microswitch cluster and the control system were available for the boys but no stimuli were scheduled for their hand- or back-pushing responses. At the start of the sessions, each boy was guided to perform one response with no stimulus consequence for it. Guidance was repeated at intervals of about 1 min during the sessions if no independent responses occurred.
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2.4.2. Intervention for hand- or back-pushing responses (B phase) The B phase included 36 and 74 sessions for the two boys, respectively. The conditions were the same as in the baseline except that the hand- or back-pushing responses activated preferred stimuli for 8 s, regardless of whether such responses occurred in the absence of the problem behavior and this behavior remained absent while the stimuli were presented. Before the last 10 sessions of the B phase, five sessions with guidance instances were used (see above). 2.4.3. Intervention for hand- or back-pushing responses and problem behavior (B1 phases) The two B1 phases included 73 and 86 sessions for Clint and 59 and 76 sessions for Gene. Five sessions with guidance instances introduced the first B1 (see above). During those phases, two changes occurred compared to the B phase. First, only hand- or back-pushing responses that occurred free from the problem behavior produced preferred stimuli. Second, the stimuli lasted the 8 s interval scheduled only if the problem behavior did not occur during that interval. If the problem behavior occurred, the stimuli were interrupted. 2.4.4. Post-intervention check The boys continued to receive sessions such as those of the last B1 phase, regularly. Eighteen of those sessions, recorded 2 months after the end of the second B1 phase, served as their postintervention check. 3. Results The data for Clint and Gene are summarized in Figs. 1 and 2, respectively. The upper graph of the figures shows the mean frequencies of hand- or back-pushing responses and the mean frequencies of
Fig. 1. The upper graph shows Clint’s mean frequencies of hand-pushing responses (white bars) and the mean frequencies of those responses performed correctly (black circles) over blocks of sessions. The number of sessions included in each block is indicated by the numeral above it. The lower graph shows Clint’s mean session time (minutes) that was free from problem behavior (white bars) and the mean stimulation time per response (seconds) elapsed without the appearance of such behavior (black circles) over the same blocks of sessions. The graphs do not include the sessions with physical guidance used toward the end of the B phase and at the start of the first B1 phase.
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Fig. 2. The two graphs show Gene’s data plotted as in Fig. 1.
those responses performed in the absence of the problem behavior (i.e., correct responses) over blocks of sessions, across all phases of the study. The lower graph of the figures shows (a) the mean time per session (in minutes) that remained free from the problem behavior over the same blocks of sessions and (b) the mean stimulation time (in seconds) per response (B phase) or per correct response (B1 phases and post-intervention check) elapsed free from the problem behavior through those blocks of sessions. The sessions are grouped into two blocks during the baseline phases and post-intervention check and three blocks during the B and B1 phases, so as to provide a view of performance trends within each of those periods. During the initial baseline, Clint’s mean frequency of hand-pushing responses was about eight per session, and Gene’s mean frequency of back-pushing responses was about four per session. Less than half of the responses were correct (performed in the absence of the problem behavior). The mean time per session without problem behavior was close to 2 min for both boys. During the B phase, the mean frequencies of hand- and back-pushing responses increased to about 23 and 12 per session. About half of those responses were correct. There were no definite positive trends during the last 10 sessions of the phase (i.e., those that followed the set of guidance sessions). The mean session time without problem behavior amounted to 2.7 and 2.8 min for Clint and Gene, respectively. The mean stimulation time per response elapsed free from problem behavior was 2.9 and 3.4 s for the two boys, respectively. During the first B1, the mean frequencies of hand- and back-pushing responses per session were about 31 and 15 for the two boys. The mean frequencies of those responses scored correct were 27 and 12, respectively. The mean session time without problem behavior amounted to 4.2 and 4.0 min for Clint and Gene, respectively. The mean stimulation time per correct response elapsed free from problem behavior was 6.7 and 6.8 s for the two boys, respectively. The boys’ performance declined during the next A phase and increased again during the second B1 phase and the post-intervention check. During those periods, their frequencies of responses and frequencies of correct responses largely matched those recorded in the first B1 phase. Their mean session time without problem behavior ranged around 4.4 min; their mean stimulation time per response elapsed free from problem behavior ranged around 7 s. The Kolmogorov–Smirnov test (Siegel & Castellan, 1988) showed statistically significant differences (p < 0.01) between the A and the B and B1 phases in the frequencies of hand- and
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back-pushing responses. Similarly, significant differences were found between the B phase and the B1 phases in the frequencies of responses and correct responses, the amount of session time without problem behavior, and the amount of stimulation time elapsed free from problem behavior. 4. Discussion These findings indicate that an intervention program based on microswitch clusters was effective in increasing adaptive responses and reducing dystonic/spastic behavior in two boys with multiple disabilities. These data support the results of the previous study dealing with a similar combination of adaptive responses and dystonic/spastic behavior (Lancioni et al., 2003) as well as the results of the other studies on microswitch clusters (Lancioni et al., 2008a). A program allowing persons with pervasive disabilities to curb dystonic/spastic behavior within a constructive activity context can be seen as a very relevant resource. Within such a program, in fact, the persons (a) develop positive response patterns and enrich their level of input with pleasant (preferred) stimulation (also determining the timing of it), and, at the same time, (b) learn to control their motor behavior and thus improve their overall performance and appearance, and limit the risks of physical deterioration (Algozzine, Browder, Karvonen, Test, & Wood, 2001; Begnoche & Pitetti, 2007). Learning to control one’s own motor behavior through appropriate engagement represents a strategy that seems in line with the notion of functional therapy (Fetters & Kluzik, 1996; Ketelaar, Vermeer, Hart, Van Petegem-van Beek, & Helders, 2001; Lancioni et al., 2008a). This type of strategy emphasizes an active (person-centered) specific motor practice as the basis for improving the targeted motor function. It can ultimately represent a form of self-directed physiotherapy as a supplement to traditional therapist-directed physiotherapy (Begnoche & Pitetti, 2007; Day, Fox, Lowe, Swales, & Behrman, 2004; Ketelaar et al., 2001). The essential variables for the success of this strategy would seem to be the compatibility of the adaptive responses with the control of the dystonic/spastic behavior, the strength of the stimulation available for the adaptive responses, and the conditions of occurrence of such stimulation. As to the first issue, the boys participating in this study seemed to be able to reconcile the performance of the adaptive hand- and back-pushing responses with the control of the problem behavior. One might at this point hypothesize, for example, that Clint would have found it more difficult to reconcile a headturning response (as opposed to the hand-pushing response adopted) with his problem behavior (Lancioni et al., 2003). The strength of the stimulation is critical to motivate the person to engage in the adaptive response and to ensure that this becomes progressively freer from the problem behavior. One might here add that the effectiveness of the stimulation depends on its strength per se as well as on the relationship between its strength and the cost of performing the adaptive response and controlling the problem behavior (Borrero & Vollmer, 2002; Ivancic & Bailey, 1996; Lancioni, Singh, O’Reilly, & Oliva, 2005; Miltenberger, 2004). Apparently, the stimulation provided in this study was fairly powerful in general and capable of competing favorably with the level of difficulty posed by adaptive responding and the control of problem behavior (Kazdin, 2001). As to the stimulation conditions, variations have been reported across the studies on microswitch clusters (Lancioni et al., 2008c). In early studies, the stimulation was presented for the scheduled time for each correct response regardless of whether the problem behavior appeared during its presentation. More recently, the stimulation was interrupted if the problem behavior appeared during its presentation. The latter approach, which was used in this study, might have been beneficial for both boys who tended to display the problem behavior during the stimulation. Interruption of the stimulation may have prevented any possibility of reinforcement for the problem behavior and may have acted as a prompt for new adaptive responding (Kazdin, 2001). The increase in adaptive responding and decline in problem behavior may be considered a relevant achievement that makes the persons look more competent, successful, and socially acceptable with positive consequences in terms of personal dignity and possibly social attention and quality of life (Petry, Maes, & Vlaskamp, 2005; Vermeer, Lijnse, & Lindhout, 2004). Obviously, the real impact and clinical relevance of the aforementioned achievement would largely depend on (a) the extension of the intervention program during the day (i.e., on an increased number of daily sessions), and (b) on the
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possibility of having a second microswitch cluster for a new form of constructive responding. Sessions with the second cluster could be alternated with sessions with the original cluster to avoid a mere repetition of the same sessions (cf. Lancioni et al., 2008b). With regard to the overall applicability/practicality of the microswitch-cluster technology, at least two different viewpoints can be forwarded. On the one hand, it may be argued that clusters such as those used in this study are quite simple as to the way the microswitches work, thus they could be considered fairly straightforward in terms of acceptability and usability within daily contexts. On the other hand, one could stress that microswitch clusters could also involve sensors more complex than those used in this study (e.g., optic sensors), that require a technical attitude that not all parents, teachers or rehabilitation personnel automatically possess. In the latter case, the question of acceptability and usability of this technology in daily contexts would not necessarily have an unequivocally positive answer (cf. Parette, Brotherson, & Blake-Huer, 2000; Scherer, Sax, Vanbiervliet, Cushman, & Scherer, 2005). In conclusion, one could argue that the present data add positive evidence to the preliminary findings on the effectiveness of microswitch clusters for promoting adaptive responses and reducing dystonic/ spastic behavior in persons with multiple disabilities. Although encouraging this evidence needs replications with new cases and adaptive responses, and with the involvement of different research groups (Richards, Taylor, Ramasamy, & Richards, 1999). Another relevant objective for future research could be that of conducting a social validation study of the microswitch-cluster approach and involving educational personnel and parents as social raters (Cunningham, McDonnell, Easton, & Sturmey, 2003). References Algozzine, B., Browder, D., Karvonen, M., Test, D. W., & Wood, W. M. (2001). Effects of intervention to promote self-determination for individuals with disabilities. Review of Educational Research, 71, 219–277. Barlow, D. H., Nock, M., & Hersen, M. (2008). Single-case experimental designs (3rd ed.). New York: Allyn & Bacon. Begnoche, D., & Pitetti, K. H. (2007). Effects of traditional treatment and partial body weight treadmill training on the motor skills of children with spastic cerebral palsy: A pilot study. Pediatric Physical Therapy, 19, 11–19. Borrero, J. C., & Vollmer, T. R. (2002). An application of the matching law to severe problem behavior. Journal of Applied Behavior Analysis, 35, 13–27. Crawford, M. R., & Schuster, J. W. (1993). Using microswitches to teach toy use. Journal of Developmental and Physical Disabilities, 5, 349–368. Cunningham, J., McDonnell, A., Easton, A., & Sturmey, P. (2003). Social validation data on three methods of physical restraint: Views of consumers, staff and students. Research in Developmental Disabilities, 24, 307–316. Day, J. A., Fox, E. J., Lowe, J., Swales, H. B., & Behrman, A. L. (2004). Locomotor training with partial body weight support on a treadmill in a nonambulatory child with spastic tetraplegic cerebral palsy: A case report. Pediatric Physical Therapy, 16, 106–113. Fetters, L., & Kluzik, J. (1996). The effects of neurodevelopmental treatment versus practice on the reaching of children with spastic cerebral palsy. Physical Therapy, 76, 346–358. Gutowski, S. J. (1996). Response acquisition for music or beverages in adults with profound multiple handicaps. Journal of Developmental and Physical Disabilities, 8, 221–231. Holburn, S., Nguyen, D., & Vietze, P. M. (2004). Computer-assisted learning for adults with profound multiple disabilities. Behavioral Interventions, 19, 25–37. Ivancic, M. T., & Bailey, J. S. (1996). Current limits to reinforcement identification for some persons with profound multiple disabilities. Research in Developmental Disabilities, 17, 77–92. Kazdin, A. E. (2001). Behavior modification in applied settings (6th ed.). New York: Wadsworth. Ketelaar, M., Vermeer, A., Hart, H., Van Petegem-van Beek, E., & Helders, P. J. M. (2001). Effects of a functional therapy program on motor abilities of children with cerebral palsy. Physical Therapy, 81, 1534–1545. Lancioni, G. E., Singh, N. N., Oliva, D., Scalini, L., & Groeneweg, J. (2003). Microswitch clusters to enhance non-spastic response schemes with students with multiple disabilities. Disability and Rehabilitation, 25, 301–304. Lancioni, G. E., Singh, N. N., O’Reilly, M. F., & Oliva, D. (2005). Microswitch programs for persons with multiple disabilities: An overview of the responses adopted for microswitch activation. Cognitive Processing, 6, 177–188. Lancioni, G. E., O’Reilly, M. F., Singh, N. N., Sigafoos, J., Oliva, D., Baccani, S., et al. (2006). Microswitch clusters promote adaptive responses and reduce finger mouthing in a boy with multiple disabilities. Behavior Modification, 30, 892–900. Lancioni, G. E., Singh, N. N., O’Reilly, M. F., Sigafoos, J., Didden, R., Oliva, D., et al. (2007a). Fostering adaptive responses and head control in students with multiple disabilities through a microswitch-based program: Follow-up assessment and program revision. Research in Developmental Disabilities, 28, 187–196. Lancioni, G. E., Singh, N. N., O’Reilly, M. F., Sigafoos, J., Oliva, D., Pidala, S., et al. (2007b). Promoting adaptive foot movements and reducing hand mouthing and eye poking in a boy with multiple disabilities through microswitch technology. Cognitive Behaviour Therapy, 36, 85–90. Lancioni, G. E., O’Reilly, M. F., Singh, N. N., Sigafoos, J., Oliva, D., Antonucci, M., et al. (2008a). Microswitch-based programs for persons with multiple disabilities: An overview of some recent developments. Perceptual and Motor Skills, 106, 355–370. Lancioni, G. E., Singh, N. N., O’Reilly, M. F., Sigafoos, J., Didden, R., Oliva, D., et al. (2008b). A girl with multiple disabilities increases object manipulation and reduces hand mouthing through a microswitch-based program. Clinical Case Studies, 7, 238–249.
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Lancioni, G. E., Singh, N. N., O’Reilly, M. F., Sigafoos, J., Oliva, D., Gatti, M., et al. (2008c). A microswitch-cluster program to foster adaptive responses and head control in students with multiple disabilities: Replication and validation assessment. Research in Developmental Disabilities, 29, 373–384. Luiselli, J. K. (1998). Treatment of self-injurious hand-mouthing in a child with multiple disabilities. Journal of Developmental and Physical Disabilities, 10, 167–174. Mechling, L. C. (2006). Comparison of the effects of three approaches on the frequency of stimulus activations, via a single switch, by students with profound intellectual disabilities. Journal of Special Education, 40, 94–102. Miltenberger, R. G. (2004). Behavior modification: Principles and procedures (3rd ed.). New York: Wadsworth. Murphy, K. M., Saunders, M. D., Saunders, R. R., & Olswang, L. B. (2004). Effects of ambient stimuli on measures of behavioral state and microswitch use in adults with profound multiple impairments. Research in Developmental Disabilities, 25, 355–370. Parette, H. P., Brotherson, M. J., & Blake-Huer, M. (2000). Giving families a voice in augmentative and alternative communication decision-making. Education and Training in Mental Retardation and Developmental Disabilities, 35, 177–190. Petry, K., Maes, B., & Vlaskamp, C. (2005). Domains of quality of life of people with profound multiple disabilities: The perspective of parents and direct support staff. Journal of Applied Research in Intellectual Disabilities, 18, 35–46. Richards, S. B., Taylor, R. L., Ramasamy, R., & Richards, R. Y. (1999). Single subject research: Applications in educational and clinical settings. New York: Wadsworth. Saloviita, T., & Pennanen, M. (2003). Behavioural treatment of thumb sucking of a boy with fragile X syndrome in the classroom. Developmental Disabilities Bulletin, 31, 1–10. Scherer, M. J., Sax, C., Vanbiervliet, A., Cushman, L. A., & Scherer, J. V. (2005). Predictors of assistive technology use: The importance of personal and psychosocial factors. Disability and Rehabilitation, 27, 1321–1331. Siegel, S., & Castellan, N. J. (1988). Nonparametric statistics (2nd ed.). New York: McGraw-Hill. Vermeer, A., Lijnse, M., & Lindhout, M. (2004). Measuring perceived competence and social acceptance in individuals with intellectual disabilities. European Journal of Special Needs Education, 19, 283–300.
Contents lists available at ScienceDirect
Research in Developmental Disabilities
Two boys with multiple disabilities increasing adaptive responding and curbing dystonic/spastic behavior via a microswitch-based program Giulio E. Lancioni a,*, Nirbhay N. Singh b, Mark F. O’Reilly c, Jeff Sigafoos d, Robert Didden e, Doretta Oliva f a
Department of Psychology, University of Bari, Via Quintino Sella 268, 70100 Bari, Italy ONE Research Institute, Midlothian, VA, USA c University of Texas at Austin, Austin, TX, USA d Victoria University of Wellington, Wellington, New Zealand e Radboud University Nijmegen, Nijmegen, The Netherlands f Lega F. D’Oro Research Center, Osimo (AN), Italy b
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 14 July 2008 Received 6 July 2008
A recent study has shown that microswitch clusters (i.e., combinations of microswitches) and contingent stimulation could be used to increase adaptive responding and reduce dystonic/spastic behavior in two children with multiple disabilities [Lancioni, G. E., Singh, N. N., Oliva, D., Scalini, L., & Groeneweg, J. (2003). Microswitch clusters to enhance non-spastic response schemes with students with multiple disabilities. Disability and Rehabilitation, 25, 301–304]. The present study was an attempt to replicate the aforementioned study with two boys with multiple disabilities. The adaptive responses selected for the boys consisted of pushing an object with the hand or the back. The dystonic/spastic behavior consisted of body arching (i.e., pushing belly and stomach forward) and leg stretching for the two boys, respectively. Initially, the boys received preferred stimulation for all hand- and back-pushing responses. Subsequently, the stimulation followed only the responses that occurred free from the dystonic/spastic behavior. The results showed that both boys increased the frequency of adaptive responses, learned to perform these responses free from the dystonic/spastic behavior, and maintained this improved performance during a 2-month post-intervention check. ß 2008 Elsevier Ltd. All rights reserved.
Keywords: Adaptive responses Dystonic behavior Microswitch clusters Multiple disabilities
* Corresponding author. E-mail address: [email protected] (G.E. Lancioni). 0891-4222/$ – see front matter ß 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.ridd.2008.07.005
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1. Introduction Persons with profound and multiple disabilities may have very low levels of adaptive responding with limited opportunities of advancing in their development and increasing their control over the environment (Gutowski, 1996; Holburn, Nguyen, & Vietze, 2004; Mechling, 2006; Murphy, Saunders, Saunders, & Olswang, 2004). Frequently, they may also present with forms of problem behavior, such as (a) inadequate body postures (e.g., forward head tilting), (b) stereotypies (e.g., hand mouthing and eye poking), and (c) dystonic/spastic behavior (e.g., back arching or leg stretching), occurring concomitant with adaptive responses and independent of them (Lancioni, Singh, Oliva, Scalini, & Groeneweg, 2003; Lancioni et al., 2008b,c; Luiselli, 1998; Saloviita & Pennanen, 2003). Educational intervention with these persons needs to encompass the dual goal of promoting adaptive responding and reducing problem behavior in order to advance their situation in a meaningful and harmonious manner (Lancioni et al., 2007a, 2008b). A form of educational intervention recently put forward to pursue such a dual goal relies on programs involving microswitch clusters (i.e., combinations of microswitches) that concurrently monitor adaptive responding and problem behavior (Lancioni et al., 2006, 2008a). Initially, these programs provide preferred stimulation for all adaptive responses irrespective of whether they occur free or in combination with the problem behavior. Once adaptive responding has increased, the programs provide preferred stimulation only for the adaptive responses that occur free from the problem behavior (Lancioni et al., 2006). For example, a microswitch cluster monitoring adaptive vocalization responses and eye poking may ensure that (a) initially, all vocalization responses are followed by positive stimulation and (b) subsequently, only vocalization responses performed in the absence of eye poking are followed by positive stimulation (Lancioni et al., 2007b). Programs with microswitch clusters have been mainly addressed to increase adaptive hand and foot responses and reduce inappropriate head position or hand/finger mouthing and eye poking (Lancioni et al., 2008a). Only one study has been reported in which microswitch clusters were used to increase adaptive responses and reduce dystonic/spastic behavior (Lancioni et al., 2003). The positive results of this study with the two participants of 9 and 14 years of age seem to indicate (a) the possibility of supplementing traditional, therapist-directed physiotherapy with the exercise of selfdirected motor control, and thus (b) the availability of an additional, personalized strategy to improve and sustain the participant’s motor condition. In light of the apparent relevance of this last type of program and the limited evidence available about it, replication efforts would seem to be warranted. The purpose of the present study was to carry out such a replication with two boys with multiple disabilities. The adaptive responses selected for the boys consisted of pushing an object with the hand or the back. The dystonic/ spastic behavior consisted of body arching (i.e., pushing belly and stomach forward) and leg stretching. 2. Method 2.1. Participants The participants, Clint and Gene, were 4.1 and 13.4 years of age, respectively, and were rated in the severe/profound range of intellectual disability, although no IQ scores were available. They had congenital encephalopathy, spastic tetraparesis with dystonic movements, scoliosis, minimal residual vision or total blindness, and lack of speech. Clint, who was born prematurely with very low birth weight and suffered from perinatal hypoxia, was also diagnosed with epilepsy. This was largely controlled through medication. Gene had been involved in microswitch programs aimed at increasing adaptive responding. Those programs were partially active when this study started. Both participants spent their time in a wheelchair or in bed. They lived at home with their parents and attended daily educational programs focusing almost exclusively on physiotherapy and general stimulation. Parents and teachers had provided informed consent for this study.
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2.2. Adaptive responses, problem behavior, and microswitch clusters The adaptive responses consisted of pushing/pressing an object with the right hand (Clint) or with the upper part of the torso’s back (Gene). The objects were flexible, plastic cylinders placed on the participant’s leg (Clint) or on the wheelchair’s upper backrest area (Gene). In both cases, the cylinders were attached to a pressure microswitch, which was activated as the boy pushed on the cylinder. The problem (dystonic/spastic) behavior was body arching, that is, pushing belly and stomach forward (Clint) or stretching one or both legs forward (Gene). The microswitch clusters consisted of a combination of the pressure microswitch for the handpushing response with a pressure microswitch on the wheelchair’s lower backrest area for body arching (Clint) or the pressure microswitch for the back-pushing response and tilt microswitches at the boy’s ankles for leg stretching (Gene). The microswitch on the wheelchair’s lower backrest area would be activated when released from pressure (i.e., when Clint arched his body). The tilt microswitches at Gene’s ankles would be activated when Gene stretched one or both legs forward. 2.3. Control system, data collection, and preferred stimuli The microswitch clusters were connected to a battery-powered, electronic control system that served to (a) turn on preferred stimuli contingent on the hand- or back-pushing responses (i.e., according to the procedural conditions described below) and (b) record the data. The data were recorded via special counters linked to the system. The recording concerned (a) the frequency of the hand- or back-pushing responses per session, (b) the frequency of these responses performed in the absence of the problem behavior (i.e., correct responses), (c) the length of time that the problem behavior remained absent during the stimulation period following each response or each correct response through the different intervention sessions (see below), and (d) the amount of session time that was free from the problem behavior. Preferred stimuli were selected through a stimulus preference screening (Crawford & Schuster, 1993). The screening covered multiple stimuli; each stimulus was presented 15–40 nonconsecutive times. Only the stimuli that were followed by positive reactions from the boys (i.e., alerting, orienting, and/or smiling) in two-thirds of the presentations or more were selected for the study. Such stimuli included various types of music, recordings of familiar persons’ speech and non-speech sounds, various noises and songs, and vibratory inputs. 2.4. Experimental conditions The study was carried out according to an ABB1AB1 design in which A represented the baseline, B represented the intervention focusing on the hand- and back-pushing responses for the two boys, respectively, and B1 represented the intervention focusing on these responses and the problem behavior together (Barlow, Nock, & Hersen, 2008). At the start of the first B1 (scheduled after different lengths of the B for the two boys), a set of five sessions occurred, which included 2–5 instances of physical guidance by a research assistant to promote the absence of the problem behavior during hand- and back-pushing responses. To control for the overall impact of these sessions, matching guidance sessions were also used during the B phase (see below). A post-intervention check occurred 2 months after the second B1. The boys received 5–14 5-min sessions a day, depending on their availability. 2.4.1. Baseline (A phases) The two baseline phases included 8 and 11 sessions for Clint and 12 sessions for Gene. The microswitch cluster and the control system were available for the boys but no stimuli were scheduled for their hand- or back-pushing responses. At the start of the sessions, each boy was guided to perform one response with no stimulus consequence for it. Guidance was repeated at intervals of about 1 min during the sessions if no independent responses occurred.
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2.4.2. Intervention for hand- or back-pushing responses (B phase) The B phase included 36 and 74 sessions for the two boys, respectively. The conditions were the same as in the baseline except that the hand- or back-pushing responses activated preferred stimuli for 8 s, regardless of whether such responses occurred in the absence of the problem behavior and this behavior remained absent while the stimuli were presented. Before the last 10 sessions of the B phase, five sessions with guidance instances were used (see above). 2.4.3. Intervention for hand- or back-pushing responses and problem behavior (B1 phases) The two B1 phases included 73 and 86 sessions for Clint and 59 and 76 sessions for Gene. Five sessions with guidance instances introduced the first B1 (see above). During those phases, two changes occurred compared to the B phase. First, only hand- or back-pushing responses that occurred free from the problem behavior produced preferred stimuli. Second, the stimuli lasted the 8 s interval scheduled only if the problem behavior did not occur during that interval. If the problem behavior occurred, the stimuli were interrupted. 2.4.4. Post-intervention check The boys continued to receive sessions such as those of the last B1 phase, regularly. Eighteen of those sessions, recorded 2 months after the end of the second B1 phase, served as their postintervention check. 3. Results The data for Clint and Gene are summarized in Figs. 1 and 2, respectively. The upper graph of the figures shows the mean frequencies of hand- or back-pushing responses and the mean frequencies of
Fig. 1. The upper graph shows Clint’s mean frequencies of hand-pushing responses (white bars) and the mean frequencies of those responses performed correctly (black circles) over blocks of sessions. The number of sessions included in each block is indicated by the numeral above it. The lower graph shows Clint’s mean session time (minutes) that was free from problem behavior (white bars) and the mean stimulation time per response (seconds) elapsed without the appearance of such behavior (black circles) over the same blocks of sessions. The graphs do not include the sessions with physical guidance used toward the end of the B phase and at the start of the first B1 phase.
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Fig. 2. The two graphs show Gene’s data plotted as in Fig. 1.
those responses performed in the absence of the problem behavior (i.e., correct responses) over blocks of sessions, across all phases of the study. The lower graph of the figures shows (a) the mean time per session (in minutes) that remained free from the problem behavior over the same blocks of sessions and (b) the mean stimulation time (in seconds) per response (B phase) or per correct response (B1 phases and post-intervention check) elapsed free from the problem behavior through those blocks of sessions. The sessions are grouped into two blocks during the baseline phases and post-intervention check and three blocks during the B and B1 phases, so as to provide a view of performance trends within each of those periods. During the initial baseline, Clint’s mean frequency of hand-pushing responses was about eight per session, and Gene’s mean frequency of back-pushing responses was about four per session. Less than half of the responses were correct (performed in the absence of the problem behavior). The mean time per session without problem behavior was close to 2 min for both boys. During the B phase, the mean frequencies of hand- and back-pushing responses increased to about 23 and 12 per session. About half of those responses were correct. There were no definite positive trends during the last 10 sessions of the phase (i.e., those that followed the set of guidance sessions). The mean session time without problem behavior amounted to 2.7 and 2.8 min for Clint and Gene, respectively. The mean stimulation time per response elapsed free from problem behavior was 2.9 and 3.4 s for the two boys, respectively. During the first B1, the mean frequencies of hand- and back-pushing responses per session were about 31 and 15 for the two boys. The mean frequencies of those responses scored correct were 27 and 12, respectively. The mean session time without problem behavior amounted to 4.2 and 4.0 min for Clint and Gene, respectively. The mean stimulation time per correct response elapsed free from problem behavior was 6.7 and 6.8 s for the two boys, respectively. The boys’ performance declined during the next A phase and increased again during the second B1 phase and the post-intervention check. During those periods, their frequencies of responses and frequencies of correct responses largely matched those recorded in the first B1 phase. Their mean session time without problem behavior ranged around 4.4 min; their mean stimulation time per response elapsed free from problem behavior ranged around 7 s. The Kolmogorov–Smirnov test (Siegel & Castellan, 1988) showed statistically significant differences (p < 0.01) between the A and the B and B1 phases in the frequencies of hand- and
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back-pushing responses. Similarly, significant differences were found between the B phase and the B1 phases in the frequencies of responses and correct responses, the amount of session time without problem behavior, and the amount of stimulation time elapsed free from problem behavior. 4. Discussion These findings indicate that an intervention program based on microswitch clusters was effective in increasing adaptive responses and reducing dystonic/spastic behavior in two boys with multiple disabilities. These data support the results of the previous study dealing with a similar combination of adaptive responses and dystonic/spastic behavior (Lancioni et al., 2003) as well as the results of the other studies on microswitch clusters (Lancioni et al., 2008a). A program allowing persons with pervasive disabilities to curb dystonic/spastic behavior within a constructive activity context can be seen as a very relevant resource. Within such a program, in fact, the persons (a) develop positive response patterns and enrich their level of input with pleasant (preferred) stimulation (also determining the timing of it), and, at the same time, (b) learn to control their motor behavior and thus improve their overall performance and appearance, and limit the risks of physical deterioration (Algozzine, Browder, Karvonen, Test, & Wood, 2001; Begnoche & Pitetti, 2007). Learning to control one’s own motor behavior through appropriate engagement represents a strategy that seems in line with the notion of functional therapy (Fetters & Kluzik, 1996; Ketelaar, Vermeer, Hart, Van Petegem-van Beek, & Helders, 2001; Lancioni et al., 2008a). This type of strategy emphasizes an active (person-centered) specific motor practice as the basis for improving the targeted motor function. It can ultimately represent a form of self-directed physiotherapy as a supplement to traditional therapist-directed physiotherapy (Begnoche & Pitetti, 2007; Day, Fox, Lowe, Swales, & Behrman, 2004; Ketelaar et al., 2001). The essential variables for the success of this strategy would seem to be the compatibility of the adaptive responses with the control of the dystonic/spastic behavior, the strength of the stimulation available for the adaptive responses, and the conditions of occurrence of such stimulation. As to the first issue, the boys participating in this study seemed to be able to reconcile the performance of the adaptive hand- and back-pushing responses with the control of the problem behavior. One might at this point hypothesize, for example, that Clint would have found it more difficult to reconcile a headturning response (as opposed to the hand-pushing response adopted) with his problem behavior (Lancioni et al., 2003). The strength of the stimulation is critical to motivate the person to engage in the adaptive response and to ensure that this becomes progressively freer from the problem behavior. One might here add that the effectiveness of the stimulation depends on its strength per se as well as on the relationship between its strength and the cost of performing the adaptive response and controlling the problem behavior (Borrero & Vollmer, 2002; Ivancic & Bailey, 1996; Lancioni, Singh, O’Reilly, & Oliva, 2005; Miltenberger, 2004). Apparently, the stimulation provided in this study was fairly powerful in general and capable of competing favorably with the level of difficulty posed by adaptive responding and the control of problem behavior (Kazdin, 2001). As to the stimulation conditions, variations have been reported across the studies on microswitch clusters (Lancioni et al., 2008c). In early studies, the stimulation was presented for the scheduled time for each correct response regardless of whether the problem behavior appeared during its presentation. More recently, the stimulation was interrupted if the problem behavior appeared during its presentation. The latter approach, which was used in this study, might have been beneficial for both boys who tended to display the problem behavior during the stimulation. Interruption of the stimulation may have prevented any possibility of reinforcement for the problem behavior and may have acted as a prompt for new adaptive responding (Kazdin, 2001). The increase in adaptive responding and decline in problem behavior may be considered a relevant achievement that makes the persons look more competent, successful, and socially acceptable with positive consequences in terms of personal dignity and possibly social attention and quality of life (Petry, Maes, & Vlaskamp, 2005; Vermeer, Lijnse, & Lindhout, 2004). Obviously, the real impact and clinical relevance of the aforementioned achievement would largely depend on (a) the extension of the intervention program during the day (i.e., on an increased number of daily sessions), and (b) on the
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possibility of having a second microswitch cluster for a new form of constructive responding. Sessions with the second cluster could be alternated with sessions with the original cluster to avoid a mere repetition of the same sessions (cf. Lancioni et al., 2008b). With regard to the overall applicability/practicality of the microswitch-cluster technology, at least two different viewpoints can be forwarded. On the one hand, it may be argued that clusters such as those used in this study are quite simple as to the way the microswitches work, thus they could be considered fairly straightforward in terms of acceptability and usability within daily contexts. On the other hand, one could stress that microswitch clusters could also involve sensors more complex than those used in this study (e.g., optic sensors), that require a technical attitude that not all parents, teachers or rehabilitation personnel automatically possess. In the latter case, the question of acceptability and usability of this technology in daily contexts would not necessarily have an unequivocally positive answer (cf. Parette, Brotherson, & Blake-Huer, 2000; Scherer, Sax, Vanbiervliet, Cushman, & Scherer, 2005). In conclusion, one could argue that the present data add positive evidence to the preliminary findings on the effectiveness of microswitch clusters for promoting adaptive responses and reducing dystonic/ spastic behavior in persons with multiple disabilities. Although encouraging this evidence needs replications with new cases and adaptive responses, and with the involvement of different research groups (Richards, Taylor, Ramasamy, & Richards, 1999). Another relevant objective for future research could be that of conducting a social validation study of the microswitch-cluster approach and involving educational personnel and parents as social raters (Cunningham, McDonnell, Easton, & Sturmey, 2003). References Algozzine, B., Browder, D., Karvonen, M., Test, D. W., & Wood, W. M. (2001). Effects of intervention to promote self-determination for individuals with disabilities. Review of Educational Research, 71, 219–277. Barlow, D. H., Nock, M., & Hersen, M. (2008). Single-case experimental designs (3rd ed.). New York: Allyn & Bacon. Begnoche, D., & Pitetti, K. H. (2007). Effects of traditional treatment and partial body weight treadmill training on the motor skills of children with spastic cerebral palsy: A pilot study. Pediatric Physical Therapy, 19, 11–19. Borrero, J. C., & Vollmer, T. R. (2002). An application of the matching law to severe problem behavior. Journal of Applied Behavior Analysis, 35, 13–27. Crawford, M. R., & Schuster, J. W. (1993). Using microswitches to teach toy use. Journal of Developmental and Physical Disabilities, 5, 349–368. Cunningham, J., McDonnell, A., Easton, A., & Sturmey, P. (2003). Social validation data on three methods of physical restraint: Views of consumers, staff and students. Research in Developmental Disabilities, 24, 307–316. Day, J. A., Fox, E. J., Lowe, J., Swales, H. B., & Behrman, A. L. (2004). Locomotor training with partial body weight support on a treadmill in a nonambulatory child with spastic tetraplegic cerebral palsy: A case report. Pediatric Physical Therapy, 16, 106–113. Fetters, L., & Kluzik, J. (1996). The effects of neurodevelopmental treatment versus practice on the reaching of children with spastic cerebral palsy. Physical Therapy, 76, 346–358. Gutowski, S. J. (1996). Response acquisition for music or beverages in adults with profound multiple handicaps. Journal of Developmental and Physical Disabilities, 8, 221–231. Holburn, S., Nguyen, D., & Vietze, P. M. (2004). Computer-assisted learning for adults with profound multiple disabilities. Behavioral Interventions, 19, 25–37. Ivancic, M. T., & Bailey, J. S. (1996). Current limits to reinforcement identification for some persons with profound multiple disabilities. Research in Developmental Disabilities, 17, 77–92. Kazdin, A. E. (2001). Behavior modification in applied settings (6th ed.). New York: Wadsworth. Ketelaar, M., Vermeer, A., Hart, H., Van Petegem-van Beek, E., & Helders, P. J. M. (2001). Effects of a functional therapy program on motor abilities of children with cerebral palsy. Physical Therapy, 81, 1534–1545. Lancioni, G. E., Singh, N. N., Oliva, D., Scalini, L., & Groeneweg, J. (2003). Microswitch clusters to enhance non-spastic response schemes with students with multiple disabilities. Disability and Rehabilitation, 25, 301–304. Lancioni, G. E., Singh, N. N., O’Reilly, M. F., & Oliva, D. (2005). Microswitch programs for persons with multiple disabilities: An overview of the responses adopted for microswitch activation. Cognitive Processing, 6, 177–188. Lancioni, G. E., O’Reilly, M. F., Singh, N. N., Sigafoos, J., Oliva, D., Baccani, S., et al. (2006). Microswitch clusters promote adaptive responses and reduce finger mouthing in a boy with multiple disabilities. Behavior Modification, 30, 892–900. Lancioni, G. E., Singh, N. N., O’Reilly, M. F., Sigafoos, J., Didden, R., Oliva, D., et al. (2007a). Fostering adaptive responses and head control in students with multiple disabilities through a microswitch-based program: Follow-up assessment and program revision. Research in Developmental Disabilities, 28, 187–196. Lancioni, G. E., Singh, N. N., O’Reilly, M. F., Sigafoos, J., Oliva, D., Pidala, S., et al. (2007b). Promoting adaptive foot movements and reducing hand mouthing and eye poking in a boy with multiple disabilities through microswitch technology. Cognitive Behaviour Therapy, 36, 85–90. Lancioni, G. E., O’Reilly, M. F., Singh, N. N., Sigafoos, J., Oliva, D., Antonucci, M., et al. (2008a). Microswitch-based programs for persons with multiple disabilities: An overview of some recent developments. Perceptual and Motor Skills, 106, 355–370. Lancioni, G. E., Singh, N. N., O’Reilly, M. F., Sigafoos, J., Didden, R., Oliva, D., et al. (2008b). A girl with multiple disabilities increases object manipulation and reduces hand mouthing through a microswitch-based program. Clinical Case Studies, 7, 238–249.
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385
Lancioni, G. E., Singh, N. N., O’Reilly, M. F., Sigafoos, J., Oliva, D., Gatti, M., et al. (2008c). A microswitch-cluster program to foster adaptive responses and head control in students with multiple disabilities: Replication and validation assessment. Research in Developmental Disabilities, 29, 373–384. Luiselli, J. K. (1998). Treatment of self-injurious hand-mouthing in a child with multiple disabilities. Journal of Developmental and Physical Disabilities, 10, 167–174. Mechling, L. C. (2006). Comparison of the effects of three approaches on the frequency of stimulus activations, via a single switch, by students with profound intellectual disabilities. Journal of Special Education, 40, 94–102. Miltenberger, R. G. (2004). Behavior modification: Principles and procedures (3rd ed.). New York: Wadsworth. Murphy, K. M., Saunders, M. D., Saunders, R. R., & Olswang, L. B. (2004). Effects of ambient stimuli on measures of behavioral state and microswitch use in adults with profound multiple impairments. Research in Developmental Disabilities, 25, 355–370. Parette, H. P., Brotherson, M. J., & Blake-Huer, M. (2000). Giving families a voice in augmentative and alternative communication decision-making. Education and Training in Mental Retardation and Developmental Disabilities, 35, 177–190. Petry, K., Maes, B., & Vlaskamp, C. (2005). Domains of quality of life of people with profound multiple disabilities: The perspective of parents and direct support staff. Journal of Applied Research in Intellectual Disabilities, 18, 35–46. Richards, S. B., Taylor, R. L., Ramasamy, R., & Richards, R. Y. (1999). Single subject research: Applications in educational and clinical settings. New York: Wadsworth. Saloviita, T., & Pennanen, M. (2003). Behavioural treatment of thumb sucking of a boy with fragile X syndrome in the classroom. Developmental Disabilities Bulletin, 31, 1–10. Scherer, M. J., Sax, C., Vanbiervliet, A., Cushman, L. A., & Scherer, J. V. (2005). Predictors of assistive technology use: The importance of personal and psychosocial factors. Disability and Rehabilitation, 27, 1321–1331. Siegel, S., & Castellan, N. J. (1988). Nonparametric statistics (2nd ed.). New York: McGraw-Hill. Vermeer, A., Lijnse, M., & Lindhout, M. (2004). Measuring perceived competence and social acceptance in individuals with intellectual disabilities. European Journal of Special Needs Education, 19, 283–300.