Reducing Pica by Teaching Children to Exchange Inedible Items for Edibles

  

Behavior Modification

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Reducing Pica by Teaching Children to Exchange Inedible Items for Edibles

Lee Kern, Kristin Starosta and Barry Eshkol Adelman

  Behav Modif 2006; 30; 135

DOI: 10.1177/0145445505283414

  

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http://bmo.sagepub.com/cgi/content/abstract/30/2/135

  

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  Behavior Modification

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Kern et al. / REDUCING PICA BEHAVIOR MODIFICATION / March 2006 10.1177/0145445505283414

Reducing Pica by Teaching Children to Exchange Inedible Items for Edibles LEE KERN KRISTIN STAROSTA

  Lehigh University

  Western Michigan University Assessment results indicated that pica exhibited by two boys with developmental disabilities was not associated with environmental contingencies. Consistent with previous research, an oral stimulation function was hypothesized. A related intervention that taught participants to ex- change inedible items for edibles was developed. Findings showed that the intervention resulted in reductions in pica for both participants. When the intervention was introduced across settings, reductions in pica were observed for one participant. However, additional training with alterna- tive pica items was necessary to produce reductions in pica across settings with the second partic-

ipant. Reductions in pica were maintained as the intervention was systematically thinned.

  Keywords: pica; functional assessment; automatic reinforcement The ingestion of inedible items, commonly known as pica, is par-

  ticularly prevalent among individuals with developmental disabilities (Danford & Huber, 1982). Because pica may result in acute medical problems including intestinal blockage, poisoning, parasitic infec- tion, and sometimes death, it has been described as one of the most serious forms of self-injury (Burde & Reams, 1973; Danford & Huber, 1982; McLoughlin, 1988). The significant consequences of pica underscore the importance of effective intervention.

  In spite of the significance of intervention, pica has been described as being particularly treatment resistant (e.g., Piazza et al., 1998). One explanation for the difficulty identifying interventions that success- _{© 2006 Sage Publications DOI: 10.1177/0145445505283414 BEHAVIOR MODIFICATION, Vol. 30 No. 2, March 2006 135-158} fully reduce pica pertains to the role of automatic reinforcement in the

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  maintenance of pica. Several studies have suggested the absence of social consequences relative to the function of pica (e.g., Piazza et al., 1998; Piazza, Hanley, & Fisher, 1996). This makes intervention dif- ficult for several reasons. First, intervention must compete with a continuous schedule of reinforcement that automatic reinforcement presumably provides. Also, it may be difficult to directly link inter- vention to assessment information unless the specific source of re- inforcement can be identified (e.g., Kennedy & Souza, 1995). Con- sequently, the vast majority of interventions have involved the use of default strategies such as mechanical restraint (e.g., Rojahn, Schroeder, & Mulick, 1980; Singh & Winton, 1984), physical restraint (e.g., Nash, Broome, & Stone, 1987; Winton & Singh, 1983), water mist (Rojahn, McGonigle, Curcio, & Dixon, 1987), and over- correction (e.g., Matson, Stephens, & Smith, 1978; Singh & Winton, 1985). Such interventions may not be permitted in many settings (e.g., Commonwealth of Pennsylvania Department of Education, 2001) or, when permitted, may be stigmatizing or socially unacceptable (Burke & Smith, 1999; Myles, Simpson, & Hirsch, 1997).

  Fortunately, a few recent research studies have shown the effective- ness of stimulus substitution or competition for reducing pica when an operant function cannot be identified. For example, functional analy- ses of three individuals with developmental disabilities, aged from 4 to 17, conducted by Piazza and colleagues (1998) indicated that pica occurred across environmental conditions (although at varying rates), including situations absent of social consequences, suggesting an automatic reinforcement function. Based on previous research (e.g., Favell, McGimsey, & Schell, 1982), the authors hypothesized that pica was maintained by reinforcement in the form of oral stimulation. Subsequently, a preference assessment was conducted to determine whether items producing oral stimulation were preferred over other items and whether noncontingent access to these items resulted in reductions in pica. Results of the preference assessments showed that participants engaged in the highest levels of interaction and lowest levels of pica when presented with items providing oral stimulation. In the final phase, the experimenters demonstrated that noncontingent access to stimuli producing oral stimulation was more effective in reducing pica than was noncontingent access to preferred items that

  Kern et al. / REDUCING PICA 137

  were not orally stimulating for all 3 participants (although the differ- ence was slight for one participant). The results also showed that an intervention consisting of noncontingent access to orally stimulating items reduced pica to near zero levels for 2 of the 3 participants. Similar reductions occurred for the 3rd participant when the intervention was combined with blocking.

  Consistent with previous research, Piazza et al. (1998) showed that intervention designed to decrease behaviors maintained by automatic reinforcement must effectively compete with the reinforcing effects of sensory stimulation. A preference assessment was conducted to identify items that would compete with pica. It is interesting to note that among the 18 to 20 items used during the preference assessments, the highest rate of item interaction and the lowest rate of pica occurred with food for all three participants. This was observed in spite of the fact that the number of food items used in the preference assessments varied across participants. This finding suggests that food items may function as a powerful substitute when addressing problem behavior maintained by oral stimulation and is supported by previous research. For example, Favell and colleagues (1982) showed that noncontin- gent access to popcorn resulted in reduction in pica presumably main- tained by automatic reinforcement for all 3 participants.

  Although an array of items may provide oral stimulation, the effec- tiveness of food is important for another reason. Stimulatory items used by Piazza et al. (1998) included a teething ring, pacifier, and so on. Although chewing or mouthing of these types of items is socially acceptable for young children, such as the 4-year-old participant in the Piazza et al. study, it would not be acceptable for older individuals.

  Goh, Iwata, and Kahng (1999) also demonstrated the effectiveness of stimulus substitution for reducing cigarette pica. During an initial intervention phase, noncontingent reinforcement was implemented using edibles identified as preferred during a preference assessment. Edibles were delivered on a fixed-time, 10-second schedule. Two of the 4 participants met end-of-treatment criterion of five consecutive 5- minute sessions without pica. However, reductions in pica were not maintained for either participant when the reinforcement schedule was thinned. Consequently, a second phase was implemented using differential reinforcement of alternative behavior. Participants were

  138 BEHAVIOR MODIFICATION / March 2006

  taught to hand a found cigarette to a therapist in exchange for a pre- ferred edible item. All of the participants engaged in exchanges, and pica was reduced with 3 of the 4 participants. In addition, the interven- tion remained effective when a novel therapist and a novel setting were introduced.

  Although both of the studies described above demonstrated the effectiveness of reinforcement-based procedures for reducing pica, there is need for further research on this topic for several reasons. First, a potential concern with both noncontingent access and rein- forcement using food is satiation. If access to highly preferred foods is provided throughout the day, an individual may satiate on food or a particular food item. It is unclear exactly how this would affect pica; however, it is likely the intervention would lose its effectiveness, at least to some degree. Another concern is dietary balance. Because preferred food items must necessarily be used, it is possible that daily caloric consumption may consist primarily of one or a few items, at the expense of a balanced intake across food groups. Therefore, research needs to examine whether schedules of reinforcement can be thinned while maintaining reductions in pica (Bell & Stein, 1992).

  A second issue, commonly noted in pica research, is limited eval- uation of intervention effectiveness across settings. As Burke and Smith (1999) note in their review, most of the intervention research for pica has been conducted in institutional or clinical settings, and the intervention setting typically differs from the setting in which the par- ticipants live. Although Goh et al. (1999) evaluated intervention ef- fectiveness across two settings, both settings were treatment rooms. Thus, the applicability to natural settings has yet to be determined.

  A final concern is that the effects of reinforcement-based pro- cedures have been evaluated across limited amounts of time. In the Piazza et al. (1998), all sessions were 10 minutes in duration, whereas sessions in the Goh et al. (1999) study were 5 minutes in length. The effectiveness of this type of intervention has yet to be evaluated throughout an individual’s day. Likewise, treatment effects have rarely been evaluated for longer than 1 week (Bell & Stein, 1992). Intervention effectiveness needs to be evaluated across time.

  In the current study, we extended previous research findings in the following ways. First, we demonstrated that the density of reinforce-

  Kern et al. / REDUCING PICA 139

  ment could be thinned while maintaining reductions in pica. Second, we implemented the intervention across settings and contexts, includ- ing natural settings with 1 of the 2 participants. Intervention was effective across settings; however, additional training sessions that included slight procedural variations to address idiosyncratic differ- ences in pica items were required with one participant.

  

METHOD

PARTICIPANTS

  Two boys participated in the current study. Orlando was an 8-year- old boy with severe mental retardation. He was nonverbal and had no history of using any type of alternative communication system. Orlando needed assistance with all daily living and self-care skills. He lived in a residential facility most of his life but was frequently visited by his mother. He attended a self-contained public school classroom for students with developmental disabilities during the day. Through- out the study, a seizure disorder was controlled with 600 mg daily of Dilantin. In addition to pica, Orlando engaged in aggression, disrup- tion, and rumination. Historically, Orlando’s pica was observed throughout his life at fluctuating frequencies with no apparent pattern. He was observed eating or attempting to eat paper, carpet, string, twigs, and straws. Reports of previous pica included fabric (e.g., clothing), metal (e.g., coins), and plastic items (e.g., toys).

  Matthew was 18 years old and had diagnoses of autism and severe mental retardation. His primary mode of communication was Picture Exchange Communication System (PECS), but he also used and re- sponded to gestures. A brain stem test indicated he was unable to hear; however, anecdotal information provided by his mother and teachers suggested some sound frequencies may have been audible. Thus, pic- tures and gestures were always paired with vocal communication. Matthew was able to complete several vocational and daily living activities (e.g., shredding, delivering mail, brushing his teeth) but needed ongoing prompting. He lived at home with his mother and attended a life skills classroom in a private school for students with

  140 BEHAVIOR MODIFICATION / March 2006

  emotional and behavioral problems. During all phases of the study, he took 500 mg of Valproic Acid and 225 mg of Dilantin daily to control a seizure disorder.

  Matthew’s challenging behaviors included aggression, disruption, and pica. Pica reportedly began when Matthew was 16 years old and quickly escalated and expanded. Items he ingested or attempted to ingest included pieces of fabric or fuzzy clothing (e.g., blankets, socks, wool sweaters, fleece jackets), foam padding from chairs and car seats, human hair, string, dust, paper items (e.g., toilet paper, paper towels), Velcro, and plastic (e.g., tape, plastic bags, various plastic packing materials). The severity of Matthew’s pica resulted in two emergency hospital admissions for an obstructed bowel. Furthermore, high rates of pica at school and the need for constant monitoring required one-to-one staffing throughout most of the school day.

  Several interventions had been previously implemented to reduce pica but were unsuccessful. For example, to address pica on the school minivan, hypothesized to occur because of inactivity, he was provided preferred items (e.g., Koosh balls, straws). However, he refused to engage with these items. At the time of the study, intervention con- sisted of removing pica items from the vicinity whenever possible and blocking pica attempts. Blocking resulted in reductions in consump- tion of inedible items but not attempts. In addition, staff members reported they did not like the intervention because it was extremely labor intensive and the blocking frequently resulted in aggression.

  SETTING

  All sessions conducted with Orlando occurred in a hospital set- ting where he was admitted for short-term treatment of challenging behaviors. Assessment, baseline, and treatment sessions were con- ducted in a small room (4.5 m by 6.0 m) equipped with a one-way win- dow for observation purposes. Probes to evaluate extension of the intervention took place in the hospital hallways and in the hospital classroom, where Orlando attended school during the day. During the final two intervention extension phases, data were collected in all areas of the hospital that Orlando typically interacted. This included hallways, the classroom, the playground, the cafeteria, and his living

  Kern et al. / REDUCING PICA 141

  quarters (a large room, approximately 12 m by 16 m, shared by four children).

  Matthew’s functional assessment was conducted across all settings where he spent time during his school day. This included all areas of the school building (classroom, gym, bathroom, hallways), the school minivan used for transportation, and two community settings where he received community-based instruction. The community settings were a game preserve and a large local discount warehouse store where he went daily to purchase food and supplies for the school’s breakfast and lunch programs. Baseline and intervention sessions were conducted in the school minivan, the community setting, and Matthew’s classroom.

  The primary dependent variable was pica. Pica for Orlando was defined as placing an inedible item past the plane of the lips. Pica for Matthew included both ingestion and attempts to ingest inedible items. Because of the absence of medical supervision in the study set- ting for Matthew, in addition to a history of medical problems result- ing from pica, attempts to ingest inedible items were blocked when- ever possible. Therefore, pica was defined as placing an inedible item past the plane of the lips or grasping an inedible item in the fingers and moving it in the direction of his mouth.

  Data were also collected on exchanges. An exchange was defined as grasping an inedible item between the fingers and handing it to another person. An exchange was coded if it was initiated indepen- dently by the participant or occurred following a gestural or physi- cal prompt. Although specific data are not available on prompted responses, prompts were seldom delivered with Orlando or with Matthew in the van and the classroom. Prompts were slightly more frequent with Matthew in the store, particularly prior to the teaching sessions. When prompts occurred, they were always at the beginning of an intervention session. No prompts were delivered during the lat- ter sessions of the intervention phases.

  Data were collected by therapists in the hospital setting (Orlando) and teaching staff who were also graduate students in the school set-

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  ting (Matthew). All data were collected using a frequency count. Data for Orlando’s functional analysis and baseline and intervention ses- sions were collected via laptop computer using the Observe program (Repp, Harman, Felce, VanAcker, & Karsh, 1989). When intervention was extended to 30 minutes and throughout the day, data were col- lected during consecutive 1-minute intervals using pencil and paper. Matthew’s data were also collected using pencil and paper; however, frequencies were coded during 5-minute intervals.

  Interobserver agreement for computer-collected data was calcu- lated using the Reliable program (Repp et al., 1989). A 5 second win- dow of agreement, in which coding of a target behavior by two inde- pendent observers within 5 seconds of one another constituted an agreement, was used. Agreement for pencil and paper data was calcu- lated by dividing the smaller frequency by the larger frequency within each interval. This yielded interval percentages, which were summed, divided by the total number of intervals in each session, and multi- plied by 100.

  Interobserver agreement data for Orlando were collected during 26% of sessions and distributed across analysis, baseline, and inter- vention sessions. Mean agreements for pica was 96.8% (range, 83% to 100%). Agreement for exchanges was 100%. Interobserver agree- ment was assessed during 23% of sessions and distributed across baseline and intervention phases for Matthew. Mean agreement for attempts was 96.9% (range, 71% to 100%). Mean agreement for ex- changes was 97.2% (range, 83% to 100%).

  A reversal design was used with both participants to evaluate the effects of the intervention on pica and exchanges. After intervention effects were demonstrated using a reversal design with Matthew in the van, the intervention was evaluated in two additional settings (store and classroom) using a multiple baseline across settings design.

  PROCEDURE Assessment . Before beginning baseline, a functional analysis was

  conducted with Orlando using procedures described by Iwata and col- leagues (1982/1994). Prior to the analysis, a consulting physician determined that ingestion of less than one piece of paper daily would

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  be physiologically benign. Thus, the room where the analysis was conducted was baited with paper, a preferred pica item, torn into small pieces.

  During the analysis, Orlando was exposed to five experimental conditions, which were play, attention, materials, escape, and alone. All sessions were 10 minutes in duration. Briefly, during attention, materials, and escape conditions, occurrences of pica were reinforced with access to brief attention, a preferred item, or a break from task, respectively. During the play condition, preferred objects were avail- able freely, and no consequences were provided following pica.

  A functional assessment was conducted with Matthew in his school setting using procedures described by Dunlap, Kern-Dunlap, Clarke, and Robbins (1991). Matthew’s teacher was interviewed using the Preliminary Functional Assessment Survey (Dunlap et al., 1991), and a semistructured telephone interview was conducted with his mother. In addition, direct observation data were collected by Matthew’s teacher using the Functional Analysis Observation Form (O’Neill et al., 1997). The frequency of pica was recorded in addition to the time, activity, setting events or discriminative stimuli (e.g., demand, difficult task, transition, alone, or no attention), perceived function (e.g., attention, item or activity, or self-stimulation), and actual conse- quence associated with each observed occurrence. Data were recorded in this manner across the entire school day for 5 consecutive days.

  . Baseline and intervention ses-

  Baseline and intervention: Orlando

  sions for Orlando were 10 minutes in duration. One or two sessions were conducted daily. During all sessions, Orlando was provided with preferred activities (e.g., musical instruments). Similar to the assess- ment, the room was baited with a piece of paper torn into small bits. Occurrences of pica were ignored.

  Following stability in baseline, a forced-choice preference assess- ment was conducted to identify preferred edible items (e.g., Fisher et al., 1992; Mason, McGee, Farmer-Dougan, & Risley, 1989). Eight items identified by staff to be preferred were used in the assessment. Each item was paired with each other item and presented to Orlando, and his selection recorded. Results indicated that corn chips were

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  Orlando’s most preferred edible. Thus, corn chips were used during intervention.

  Intervention consisted of teaching Orlando to exchange the inedi- ble item for the preferred edible item (chip). Prior to beginning inter- vention, an initial teaching session was conducted, lasting approxi- mately 45 minutes. During this teaching session, each time Orlando grasped the inedible item, he was verbally prompted to hand it to a therapist in exchange for a chip. Specifically, the therapist stated, “Orlando, if you want a chip, hand me the paper.” This verbal prompt was accompanied by a physical prompt (therapist grasped Orlando’s hand and placed the inedible item in his or her own) during the initial trials of the teaching session. Each time an exchange occurred (either independent or prompted), the therapist provided Orlando a chip. Pica occurrences were ignored. As Orlando’s independence in exchanges increased, first physical then verbal prompts were faded. The teaching session ended after 10 consecutive exchanges without prompting.

  During the intervention phase, at the beginning of each session Orlando was shown the chips and instructed, “Orlando, if you want a chip, hand me the paper.” Each time Orlando handed the therapist a piece of paper, he received a chip. When pica occurred, the initial instruction was reissued. Although the instruction was reissued con- tingent on pica throughout the study, the initial prompt and chip dis- play occurred only during the first nine intervention sessions. As in baseline and training, no blocking occurred, and pica occurrences were ignored.

  Following a decrease in pica and an increase in exchanges, baseline was reimplemented. On stability in baseline, intervention was again introduced. During the first two intervention phases, Orlando received an edible contingent on handing the therapist the inedible item on an fixed ratio (FR) 1 schedule. In an attempt to decrease the likelihood of satiation, the frequency of food delivery was thinned to an FR 2 sched- ule. Although Orlando received fewer chips during this phase, the fre- quency of exchanges remained high. Thus, a delay to reinforcement was added. After Orlando presented a pica item to the therapist, he or she stated, “Wait,” while holding up a hand, palm out, in a stop ges- ture. Initially, the latency was 10 seconds following presentation of the inedible item to the therapist. Following consistently low rates of

  Kern et al. / REDUCING PICA 145

  pica, this was increased to 20 seconds. During the final intervention phase, the schedule of reinforcement was thinned to an FR 3 schedule, and the delay to reinforcement remained at 20 seconds.

  During intervention, periodic probes were conducted to ensure the training would generalize outside of the intervention setting. The ini- tial probe lasted 10 minutes and was conducted in the hallways of the hospital. As with intervention, the hallways were baited with paper. The second set of intervention extension probes lasted 10 minutes and was conducted in Orlando’s classroom. Orlando’s teacher involved him in ongoing classroom activities, and in this case the setting was not baited. During all of the probes, intervention was implemented by Orlando’s therapist.

  Following the final intervention phase, the effectiveness of the intervention was assessed during a longer period of time and across settings and care providers. During these assessments, reinforcement remained on an FR 3 schedule with a 20 second delay. Initially, ses- sions were lengthened to 30 minutes and occurred at various times during the day. Sessions took place either in the classroom, on the playground, or in the hallways when Orlando was transitioning to one of these settings. These sessions were also conducted by Orlando’s therapist.

  During the final phase, the procedures were implemented through- out the day and across settings (in the classroom, on the playground, at school, in the kitchen, and in the living quarters). The exchange proce- dures were implemented by the respective care provider in each set- ting (i.e., therapist, child care worker, or teacher). Data were collected periodically throughout the day during the first 15 minutes of each hour (105 minutes total) between 9:00 a.m. and 3:15 p.m.

  . Following the functional

  Baseline and intervention: Matthew

  assessment, baseline and intervention sessions were initially con- ducted in the school minivan. This setting was selected for initial intervention evaluation because rates of pica were highest in this set- ting. Subsequently, sessions were conducted in a local discount ware- house and in Matthew’s classroom.

  Sessions in the school minivan occurred during 15 minute to 20 minute traveling trips that occurred between 9:30 and 11:30 a.m. each

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  weekday morning. Trips included Matthew’s entire class (3 class- mates and 3 staff). Matthew sat in the middlemost seat with one teach- ing staff member beside him. Another teaching staff member and two students sat behind him, whereas a third staff member and a student sat in the front seats.

  Sessions in the local discount warehouse took place from approxi- mately 9:45 a.m. to 10:30 a.m. While in the store, Matthew was always accompanied by his teacher. Matthew’s classmates and the classroom staff either shopped together with Matthew in one large group or broke into two smaller groups. At the store, Matthew was prompted and assisted to partially participate in shopping activities (e.g., pushing the cart, selecting items from the shelf and placing them in the cart).

  The third setting where sessions occurred was the classroom, be- tween 8:00 a.m. and 9:00 a.m. During classroom sessions, Matthew was moving about the classroom, sitting at a round table, or sitting next to vocational materials. Activities included the morning routine (e.g., hanging his jacket, completing self-care activities), eating breakfast, receiving table-top instruction (e.g., practicing with PECS), engaging in leisure activities, or performing vocational tasks (e.g., sorting mail, shredding paper). The classroom teacher worked exclusively with Matthew while his classmates and the other teaching staff were involved in their own individualized routines and programs. As in all previous sessions, for safety reasons described above, all pica attempts were blocked whenever possible.

  Following baseline, a forced-choice preference assessment was conducted in a manner similar to that conducted with Orlando using five edible items identified by staff and Matthew’s mother as pre- ferred. The assessment revealed that Matthew selected potato chips almost exclusively. Thus, potato chips were used during intervention.

  Intervention was initially introduced in the minivan. Items Matthew attempted to ingest in this setting included fuzz from his or others’ clothing, human hair (which he removed from others’ heads), and any various remains left in the van (e.g., paper or plastic items).

  Prior to initiating intervention in the minivan, teaching sessions were conducted by Matthew’s teacher in the classroom using a dis- crete trial, table-top format. This was done because Matthew’s teacher

  Kern et al. / REDUCING PICA 147

  believed that acquisition would occur more quickly in a structured, less distracting environment. During teaching sessions, Matthew’s teacher sat across the table from him. Fuzz from a sweater was placed on the table, and Matthew’s teacher provided a verbal prompt by stat- ing, “If you want the chip, you have to give me the fuzz,” accompanied by a gestural prompt in the form of pointing to the fuzz and holding out her hand. Immediately following the verbal and gestural prompts, another teaching staff member provided a full physical prompt (hand- over-hand) from behind. After 10 prompted trials, a probe of 10 unprompted trials was conducted to assess independence. During unprompted trials, the teacher sat quietly at the baited table across from Matthew while holding a chip. All pica attempts were blocked. A predetermined criterion was established of 70% independence on three consecutive probes of 10 trials prior to introducing the inter- vention in the minivan. Criterion was achieved in 7 training sessions. Intervention was then introduced in the minivan.

  During the intervention sessions in the minivan, Matthew’s teacher made sure that chips were visible. Whenever possible, pica attempts were blocked. After low rates of pica and high rates of exchanges were observed, a return to baseline was conducted. Intervention was again introduced following an increase in pica and decrease in exchanges.

  Similar to Orlando, the rate of exchanges remained high through- out both intervention phases. Therefore, a delay to reinforcement was introduced in a fashion identical to Orlando. Specifically, the duration between Matthew’s presentation of the inedible item and the teacher’s provision of the chip was systematically increased by 5 second incre- ments every 1 or 2 days.

  Following intervention in the minivan, intervention was introduced in the community store and Matthew’s classroom. Consistent with a multiple baseline design, baseline was introduced simultaneously in both settings, and intervention was later staggered across the two settings.

  After intervention was introduced in the store, unlike the minivan, rapid reductions in pica were not observed. Although Matthew con- tinued to exchange fuzz, the intervention was not effective with other objects. Pica attempts were targeted at Velcro used to attach product and price descriptions to shelving, his shirt collar, his jacket sleeve,

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  and human hair. Matthew also was making repeated attempts to pull hair from the heads of his teachers for pica purposes. For these rea- sons, five additional teaching sessions were conducted prior to store sessions 14, 15, 19, 21, and 22 using the alternative pica items.

  Because pica items in the store did not lend themselves to removal and exchange, Matthew was taught to touch the item then hold out his hand to receive a chip. Prompting procedures were the same as during the initial training sessions. The first three teaching sessions were con- ducted with hair. As with the initial teaching sessions, 10 prompted trials were followed by a probe of 10 unprompted trials to assess inde- pendence. During these three probes, independence was 100%, 90%, and 90%. Clothing was used for the next two teaching sessions. Ten prompted trials were conducted with Matthew wearing his jacket then wearing his shirt. As with hair, each set of prompted trials was fol- lowed by probe trials. During all probe sessions, independence ranged from 90% to 100%.

  Following intervention implementation in the store, it was subse- quently introduced in the classroom. Although variability in pica and exchanges continued to be observed in the store, there appeared to be a decreasing trend. In addition, the school staff believed that the inter- vention was effective and felt an urgency to extend it to the classroom rather than continue the more labor-intensive baseline procedures. Intervention procedures in the classroom were identical to the mini- van and store.

  

RESULTS

ASSESSMENTS

  Orlando’s functional analysis showed that pica occurred across all experimental conditions at somewhat consistent rates (play = 72 per hour, attention = 56 per hour, materials = 81 per hour, escape = 78 per hour, and alone = 90 per hour).

  All sources of information obtained during the functional assess- ment conducted with Matthew indicated that pica occurred through- out the day and was unrelated to any specific environmental variable.

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  Direct observation data reflected the occurrence of pica in all settings regardless of the time of day, activity, or staff present, with the excep- tion of when he was eating (e.g., lunch, snack), during which time almost no pica attempts occurred (range, 0 to 5 per hour). Although pica was observed across all settings, the frequency varied. This vari- ability appeared to be related to the availability of preferred pica items (e.g., sweater, paper) rather than any specific environmental variable. For example, mean occurrence of pica in the gym was 11 per hour, whereas mean occurrence in the van was 102 per hour. The occurrence of pica across all settings was consistent with information obtained from interviews with Matthew’s teacher and mother.

  BASELINE AND INTERVENTION Baseline and intervention data for Orlando are shown in Figure 1.

  The number of pica and exchange occurrences per session was con- verted to number per hour for reporting purposes. During the initial baseline session, occurrences of pica per hour were high, ranging from 138 to 228. No exchanges occurred. After implementing inter- vention, pica immediately decreased, and exchanges occurred during two of the three sessions. On return to baseline, occurrences of pica increased and were highly variable (range, 24 to 300), whereas ex- changes returned to zero. Reimplementation of the intervention pro- cedures resulted in a reduction of pica to near zero levels and an increase in exchanges. The first intervention extension probe, con- ducted in the hallways, resulted in rates of pica and exchanges com- parable to intervention.

  Following the intervention extension probe, reinforcement was thinned to an FR 2 schedule. Pica remained low; however, exchanges continued at high rates, although the variability increased. Similar rates of pica and exchanges occurred with the addition of a 10 second delay to reinforcement.

  Three additional intervention extension probes then were con- ducted in the classroom. A decreasing trend in pica was observed across the three probes. Exchanges continued to occur although at a lower rate than during the baited analog sessions.

  150 BEHAVIOR MODIFICATION / March 2006 _{Baseline Exchange Intervention Intervention Extension Probe Intervention Extension 225 250 275 10 s Delay 20 s Delay 20 s Delay} 300 _{attempt Base- line FR 2 FR 2 + FR 2 + FR 3 + min Day 30 Across Hour Per 125 150 175} 200 _Number 100 _{25 50 75 exchange Orlando}

  1 ^{3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61} _Sessions Figure 1. Number per hour of pica attempts and exchanges for Orlando.

  During the next phase, the delay to reinforcement was increased to 20 seconds. Pica remained low, and the overall frequency of ex- changes decreased. When the schedule of reinforcement was again thinned to an FR 3 schedule, zero rates of pica occurred in six out of seven sessions. Although the number of exchanges per hour was highly variable, the mean number decreased. The final intervention extension sessions across multiple settings, both at 30 minutes and throughout the day, resulted in continued low rates of pica and as low rates of exchanges.

  Baseline and intervention sessions conducted with Matthew are shown in Figures 2 and 3. As with Orlando, data are displayed as num- ber per hour. Baseline data in the van (Figure 2) indicate high rates of pica and the absence of exchanges. On implementation of interven- tion, pica remained high during the initial session, then immediately decreased and remained low throughout the phase. Exchanges were initially variable but increased to high levels. Return to baseline resulted in an increase in pica and the absence of exchanges. When intervention was reimplemented, a decreasing trend in pica occurred, whereas exchanges decreased. The addition of a delay to reinforce- ment resulted in continued low frequencies of pica and a decreasing trend in the occurrence of exchanges.

  Baseline and intervention data in new settings (store and class- room) are reported in Figure 3. During baseline, pica attempts were observed in both settings, and no exchanges occurred. Following implementation of intervention, pica attempts gradually decreased over time. Additional teaching sessions conducted prior to trips to the store resulted in a slight decrease in pica attempts, although variability continued to be observed. Exchanges were also highly variable and occurred during almost all intervention sessions.

  

DISCUSSION

  The exchange intervention effectively reduced pica exhibited by both of the participants. Pica reductions in the initial training setting

  Kern et al. / REDUCING PICA 151

  25 ^{50 450 425 400 375 350 325 300 275 250 225 200 175 150 125 75 100} _{1 5 10}

₁₅

_{20 25} ^Number _{30 Sessions} ^{Per Hour Matthew Van attempt exchange Baseline Exchange Intervention Baseline Exchange Intervention Time Delay (seconds) 5 10 15 20 25 30 35 40} Figure 2. Number per hour of pica attempts and exchanges for Matthew in the van.

  152 BEHAVIOR MODIFICATION / March 2006 _{200 Baseline Excha nge Intervention (357) (210) (297) 150} 175 _{125 attempt T e a c h i n g S e s s i o n s Matthew Store} 100 _{50 75 -25} 25 exchange _{175 200} -50 150 _{125 100 Classroom 25 50}

  75

  5 ^{10 15 20 25 30 35 40} Sessions

Figure 3. Number per hour of pica attempts and exchanges for Matthew in the store and

classroom.

  occurred immediately. However, in Matthew’s case, when the inter- vention was introduced in new settings, reductions in pica were not

  Kern et al. / REDUCING PICA 153

  immediately observed. This is most likely because items with the highest rates of pica in the new settings differed from those used in the training setting. It was necessary to conduct additional teaching ses- sions using alternate pica items. The slow acquisition rate may also be attributable to fewer opportunities to practice the intervention. Pica was introduced initially in the van because the rate was highest in that setting. Because lower baseline rates of pica were observed in the other two settings, opportunities to practice exchanges were less fre- quent than in the van. Another possible explanation is that the van was a confined space compared with the other settings. Therefore, pica attempts were easier to monitor, and the presence of the discriminative stimulus (chips) may have been more apparent. Implementation of the pica intervention across settings extends the existing literature base, and idiosyncratic problems with implementation in different settings underscores the need to examine pica interventions across environ- ments and in natural contexts.

  Although both of the participants engaged in pica across settings, the assessment data for Matthew indicated variability in the frequency across settings. Anecdotal data and the overall frequency of pica and exchanges during probes across settings conducted with Orlando also indicated variable rates of pica across settings. There appeared to be two explanations for this variability. First, the availability of preferred pica items differed across settings. In addition, alternative activities sometimes competed with pica. For example, both boys were required to complete tasks in the classroom setting, during which time pica was sometimes reduced. This may also explain the reduced rate of both pica and exchanges when intervention was introduced across the day with Orlando. The variability of pica across settings suggests that multiple factors should be considered (e.g., activity, item availability) when interpreting functional assessment or analysis data and when evaluating intervention effectiveness.

  An advantage of the current intervention was control of edible intake via delivery by the teacher or therapist. Unlike free access to food (e.g., Favell et al., 1982), the risk of satiation can be reduced by modifying schedules of reinforcer delivery. An additional potential advantage involves the link between pica and delivery of edible items. Receipt of an edible required the participant to present a pica item. It is

  154 BEHAVIOR MODIFICATION / March 2006

  possible that this relationship may help to establish that consumption of certain edible items is preferable to consumption of certain inedible items, a relationship that may not be easily established through free access to food or noncontingent reinforcement.

  This study also demonstrated that the schedule of reinforcement could be thinned without accompanying increases in pica. Goh et al. (1999) were unsuccessful in their attempts at schedule fading. How- ever, they suggested the lack of success may have been a result of abrupt increases in schedule thinning. The success of gradual changes in the current study support the conclusions of Goh and colleagues. Still, the extent of reinforcement thinning is a limitation. Reinforce- ment was not thinned beyond an FR 3 schedule and a 40 second delay. Further research should evaluate continued thinning of reinforce- ment. Also, additional research might evaluate alternative methods of schedule thinning that are efficient and maintain low rates of both pica and exchanges (e.g., Hanley, Iwata, & Thompson, 2001).

  Several additional limitations and areas warranting further re- search should be noted. Although intervention for Orlando involved only item exchange, for safety reasons blocking was also imple- mented during intervention with Matthew. It seems unlikely that the blocking had much effect on pica given that it was routinely used throughout the day and was also used during baseline sessions with- out accompanying reductions in pica. However, the possibility that it had an additive effect cannot be ruled out. Further research might con- duct a component analysis to parcel out the independent contribution of blocking.

  Another limitation is that baseline data were not collected for Orlando in settings outside of the treatment setting. Thus, compara- tive data to evaluate the effects of the intervention are not available.

  Because the initial intervention setting was baited, pica occurred at higher rates than in other settings. Nonetheless, pica was present across all settings, which was one reason for his hospitalization. Also, anecdotal information from therapists and family members indicated general reductions in pica throughout the day.

  The topographical similarity of the alternative response (exchange) to the initial steps in the chain of a pica response may raise concerns (e.g., Goh et al., 1999). Although concern is valid, there also may be

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  advantages to the exchange intervention. First, unlike other alterna- tive responses that could have been taught, the exchange response was physically incompatible with pica and may have expedited the effec- tiveness of the intervention by directly teaching that the alternative incompatible response resulted in reinforcement that was presumably preferred. In addition, because part of the chain required to obtain reinforcement was already a part of the participants’ repertoire, this may have facilitated acquisition of the alternative response. Finally, the intervention required the participant to identify and remove pica items from the environment, thereby decreasing the availability of those items.

  Another limitation is that procedural fidelity data were not col- lected. In Orlando’s case, the intervention procedures were imple- mented throughout the day by several different child care workers. All of the staff indicated that the procedures were easy to implement, and data collectors and supervisors noted that procedures were imple- mented with reasonable integrity. However, there were occasions when therapists noted that the ratio and delay to reinforcement sched- ules were not implemented completely accurately. Nonetheless, the data, although limited, indicate that low rates of pica were maintained.