A Comparison of Demand Fading and a Dense Schedule of Reinforcement During Functional Communication Training

Abstract

Ample research indicates that functional communication training (FCT) is an effective intervention to reduce challenging behavior. The purpose of this study was to evaluate the effect of demand fading on escape-maintained challenging behavior, mands, and task completion for 2 children with autism spectrum disorder. The study utilized an embedded reversal and alternating-treatments design to evaluate the efficacy of the intervention and compare the efficacy of the demand fading and dense schedule conditions. During FCT, participants were taught 2 mand topographies, one of which was associated with demand fading. FCT with and without demand fading resulted in decreases in challenging behavior for both participants. FCT with demand fading resulted in higher task completion for both participants. The effect of demand fading on the rate of mands varied by participant. Results provide further support for the use of FCT. The importance of intervention fading in the treatment of challenging behavior is discussed.

Approximately one in four children with autism spectrum disorder (ASD) engage in challenging behavior, which can affect the child’s day-to-day functioning, social interactions, and academic outcomes (Hartley, Sikora, & McCoy, 2008). Functional communication training (FCT) is often recommended for the reduction of challenging behavior for children with ASD (Tiger, Hanley, & Bruzek, 2008; Wong et al., 2015). FCT involves teaching and providing function-based reinforcement for a socially appropriate, functionally equivalent communicative response in order to reduce challenging behavior (Carr & Durand, 1985). At least 215 studies have evaluated the efficacy of FCT across a variety of populations (Gerow, Davis, Radhakrishnan, Gregori, & Rivera, 2018). This body of research indicates that FCT is an evidence-based practice for children with ASD and is effective across functions and topographies of challenging behavior (Gerow et al., 2018). The previous literature also highlights the importance of specific intervention components, which are now common parts of the implementation of FCT, such as extinction following challenging behavior and selecting an efficient communicative response (Hagopian, Fisher, Sullivan, Acquisto, & LeBlanc, 1998; Horner & Day, 1991).

FCT and Demand Fading

Although FCT is highly effective at reducing challenging behavior, typical implementers, such as parents and teachers, may have difficulty implementing the intervention if the alternative communication response occurs at high rates (Hagopian, Boelter, & Jarmolowicz, 2011). For example, a busy teacher may abandon the implementation of an intervention if the intervention requires the teacher to provide function-based reinforcement every 30 s. Therefore, simply teaching a communication response and recommending that it be reinforced on a continuous reinforcement schedule at all times and across all settings is neither feasible nor practical (Hagopian et al., 2011; Tiger et al., 2008). Schedule thinning, or systematically providing less frequent reinforcement for appropriate responses, can alleviate the difficulty associated with providing reinforcement contingent on each instance of appropriate behavior (Hagopian et al., 2011).

There are several ways to systematically thin reinforcement schedules during FCT, such as multiple schedules, delay of reinforcement, and chained schedules. Chained schedules involve requiring the individual to engage in two or more behaviors, in a particular sequence, in order to obtain reinforcement (Hagopian et al., 2011). Demand fading is one form of a chained schedule that is often used for the treatment of escape-maintained challenging behavior (Berg, Wacker, Harding, Ganzer, & Barretto, 2007; Mildon, Moore, & Dixon, 2004). In the context of FCT to reduce escape-maintained challenging behavior, demand fading involves requiring the completion of a certain number of tasks prior to reinforcing a communicative response (Hagopian et al., 2011). The number of tasks required increases throughout the intervention.

Demand fading is the most commonly used form of schedule thinning with FCT for escape-maintained challenging behavior (Hagopian et al., 2011). For example, Lalli, Casey, and Kates (1995) implemented demand fading with three individuals with developmental disabilities who engaged in escape-maintained challenging behavior. During FCT, each participant was taught to communicate appropriately to request a break from the work tasks. Throughout the intervention, the number of tasks required prior to receiving reinforcement contingent on asking for a break increased from 1 to 16 tasks. This research, along with other previous studies, provides support for the use of FCT, as well as FCT with demand fading (Hagopian et al., 2011).

Resurgence of Escape-Maintained Challenging Behavior

Previous studies have evaluated the extent to which resurgence of challenging behavior, or the reemergence of challenging behavior under extinction conditions, occurs following the implementation of FCT (e.g., Berg et al., 2015; Hoffman & Falcomata, 2014; Marsteller & St. Peter, 2014; Volkert, Lerman, Call, & Trosclair-Lasserre, 2009; Wacker et al., 2011, 2013). These studies, along with reviews of the literature (e.g., Briggs, Fisher, Greer, & Kimball, 2018; Radhakrishnan, Gerow, & Weston, 2019), indicate that challenging behavior tends to resurge under extinction conditions and during transitions to thinner schedules of reinforcement. Typical implementers, such as parents and teachers, may have difficulty implementing FCT consistently over extended periods of time, highlighting the importance of evaluating the extent to which effective treatments also prevent resurgence (Lattal & St. Peter Pipkin, 2009). Resurgence is defined as the occurrence of a previously reinforced behavior under conditions in which a more recently reinforced alternative behavior contacts extinction (Wacker et al., 2013). To evaluate resurgence, three conditions are typically assessed in sequential order: (a) reinforcement is provided contingent on Response A, (b) Response A is placed on extinction and reinforcement is provided contingent on Response B, and (c) both Responses A and B are placed on extinction (Epstein, 1985; Lattal & St. Peter Pipkin, 2009; Lieving & Lattal, 2003). In the case of FCT, Response A is a topography of challenging behavior, and Response B is a functionally equivalent communicative response. In the context of FCT, resurgence is typically evaluated by (a) providing reinforcement contingent on challenging behavior, (b) implementing FCT, in which the challenging behavior results in extinction, and appropriate communication results in reinforcement, and (c) implementing extinction contingent on both challenging behavior and appropriate communication (e.g., Berg et al., 2015; Volkert et al., 2009; Wacker et al., 2011). The reoccurrence of challenging behavior during the third phase is considered resurgence, especially if it occurs at rates similar to or higher than initial baseline responding (Wacker et al., 2011).

To date, at least 10 studies have evaluated the resurgence of challenging behavior following FCT using a similar three-phase evaluation (Berg et al., 2007, 2015; Fuhrman, Fisher, & Greer, 2016; Gratz, Wilson, & Glassford, 2019; Hoffman & Falcomata, 2014; Marsteller & St. Peter, 2014; Padilla Dalmau et al., 2011; Volkert et al., 2009; Wacker et al., 2011, 2013). Of those studies, five studies have assessed the resurgence of challenging behavior maintained by escape from demands (Berg et al., 2007, 2015; Volkert et al., 2009; Wacker et al., 2011, 2013). The extant literature on resurgence of escape-maintained challenging behavior indicates that long-term implementation of FCT, multiple exposures to extinction, and demand fading result in reductions in the resurgence of challenging behavior maintained by escape from demands (Wacker et al., 2011, 2013). A study by Wacker et al. (2013) demonstrated that multiple exposures to extinction, demand fading, and long-term treatment (5–7 months) resulted in decreases in resurgence in the final extinction condition. Based on this research, there is a need for continued investigation of specific intervention components that reduce the resurgence of escape-maintained challenging behavior.

Purpose and Research Questions

Although there have been previous studies demonstrating the efficacy of FCT and the efficacy of FCT with schedule-thinning procedures, few studies have directly compared the efficacy of various schedules of reinforcement used with FCT. Hagopian, Toole, Long, Bowman, and Lieving (2004) compared the effects of dense-to-lean versus fixed-lean schedules for the treatment of challenging behavior with three individuals with developmental disabilities. For each of the participants, a multiple schedule (i.e., time-based schedule) was used with either systematic increases in the length of the extinction component (dense-to-lean condition) or a consistently long extinction component (fixed-lean condition). The results indicated that the dense-to-lean condition resulted in lower rates of challenging behavior but that the fixed-lean condition resulted in faster achievement of treatment goals. However, there is a need for similar research with response-based schedules and research comparing dense-to-lean to fixed-dense schedules. The purpose of the present study was to compare FCT with demand fading to FCT with a dense schedule of reinforcement. Specific research questions included the following:

1. Does demand fading result in the reduction of escape-maintained challenging behavior during the intervention as compared to a dense schedule of reinforcement?

2. Does demand fading result in an increase in task completion during the intervention as compared to a dense schedule of reinforcement?

3. Does demand fading result in a decrease in mands during the intervention as compared to a dense schedule of reinforcement?

4. Does demand fading result in a reduced resurgence of challenging behavior as compared to a dense schedule of reinforcement?

Method

Participants

Two participants were included in this study. The participants attended a university-affiliated clinic or were on the wait list for the university-affiliated clinic, which provided applied behavior analytic interventions to children with disabilities. Each of the participants met the following inclusion criteria: (a) the parent reported that the child engaged in frequent challenging behavior and (b) the functional analysis indicated that the child engaged in challenging behavior that was maintained by escape from demands. Participants were not included in this study if the challenging behavior was too severe (i.e., was likely to cause harm to the child or others during the 5-min sessions). Participants were required to complete the first four phases of the treatment evaluation to be included in the study so that a comparison between the conditions could be conducted.

Noah was a Hispanic boy aged 6 years 7 months who was diagnosed with ASD and attention deficit hyperactivity disorder by a developmental pediatrician at the age of 4. Noah attended the university-affiliated clinic to receive applied behavior analytic intervention 2 hr per week. Noah also attended kindergarten with typically developing peers in a class of 15 students and 2 teachers. He lived with his parents and younger sister. During the parent interview, his mother reported that Noah engaged in screaming and kicking when asked to transition from a high-preferred activity to a low-preferred activity or when asked to do a difficult task at school.

Liam was a Caucasian boy aged 4 years 11 months who was diagnosed with ASD and a speech delay by an educational diagnostician at the age of 3. Liam was on the wait list for the university-affiliated clinic and received applied behavior analytic intervention at a private clinic for 40 hr per week. He lived with his parents and three siblings. During the parent interview, his mother reported that Liam engaged in hitting and headbutting when asked to do a difficult task or when denied access to preferred foods. According to his mother, hitting occurred approximately two to three times a day.

Setting and Materials

All sessions occurred in an instructional room within the university-affiliated clinic. Each room contained three chairs, a table, and materials for the session. Items used during the sessions included academic materials and toys, such as blocks, cars, and action figures. The therapist identified each child’s most preferred item via a multiple-stimulus without replacement preference assessment (DeLeon & Iwata, 1996). Each preference assessment included five toys, identified during the parent interview. The therapist and at least one observer were present during each session. The observer used a tablet computer to video record sessions, and data were collected via paper and pencil. The therapist was a doctoral student in educational psychology for one participant and a professor in educational psychology for the other participant. The observers were either professors or doctoral students in educational psychology

Data Collection

Study visits occurred two to three times per week over the course of 9 weeks for Noah and 13 weeks for Liam. The session length varied based on the frequency of the child’s challenging behavior. Noah’s sessions were 5 min in length, and Liam’s sessions were 10 min in length. Two to four sessions occurred per study visit, with an average of two sessions per visit.

Dependent Measures

The observers collected data on challenging behavior, mands, and task completion during each session. For each target behavior, the observer recorded the frequency of behavior within the session. The experimenters converted the frequency to responses per minute for each target behavior (i.e., frequency divided by the number of minutes in the session). Noah’s target challenging behavior was aggression, which was defined as hitting, kicking, or pushing the therapist or attempting to hit, kick, or push the therapist. Liam’s target challenging behavior was also aggression, defined as hitting, kicking, and headbutting the therapist or attempting to hit, kick, or headbutt the therapist.

Data were collected on appropriate behaviors in addition to the target challenging behaviors. The observers collected data on the frequency of independent target mands (“All done,” and “Break please.”) during the treatment evaluation. Only the target mands for the condition were reported during the FCT and extinction phases. During the baseline phases, all specific requests for the function-based reinforcement counted as a mand. If the participant was taught to use picture exchange (Noah only), both picture exchange and verbalizations counted as independent mands. Simultaneous occurrences of picture exchange and verbalizations were counted as one mand. Finally, the observer recorded data on task completion, defined as correctly complying with the demand following either verbal instruction or verbal instruction with a model prompt.

Interobserver Agreement (IOA)

An independent observer collected data on each of the dependent measures during at least 30% of sessions in each phase and for each participant. The independent observer was a doctoral student or professor in educational psychology. To assess agreement between observers, each session was divided into 10-s intervals. An agreement was scored if both observers recorded the exact same frequency of the target behavior in the interval. IOA was calculated as the percentage of 10-s intervals with exact agreement (i.e., the number of intervals with exact agreement divided by the total number of intervals in the session multiplied by 100). The average IOA for Noah was 98% (range 80%–100%) for challenging behavior, 94% (range 83%–100%) for mands, and 94% (range 77%–100%) for task completion. For Liam, average IOA was 99% (range 90%–100%) for challenging behavior, 98% (range 93%–100%) for mands, and 94% (range 75%–100%) for task completion. IOA was above 80% on average for each participant, phase, and rater.

Experimental Design

This study consisted of a functional analysis, treatment evaluation, and extinction-challenge evaluation.

Functional Analysis

The functional analysis included four conditions: play, escape, tangible, and attention. A multielement design was used to compare the child’s behavior during each condition (Kennedy, 2005). The order of sessions was randomized within each set of four conditions.

Treatment Evaluation

The treatment evaluation consisted of a reversal design (Kennedy, 2005) with five or seven phases: (a) baseline, (b) FCT, (c) baseline, (d) FCT, (e) extinction, (f) FCT (for Liam only), and (g) extinction (for Liam only). Extinction phases were implemented following the completion of the first four phases to evaluate the extent to which demand fading affected the resurgence of challenging behavior. In the FCT and extinction phases, there were two different conditions. The conditions were presented within an alternating-treatments design, with the order of the conditions randomized within each set of two sessions. A different mand (“All done,” or “Break please.”) and additional stimulus cues were associated with each condition. The pairing of conditions with mands and additional stimulus cues was counterbalanced across participants (see Table 1).

Table 1.

Method: Counterbalancing Stimuli Associated with Each Condition

Condition	Participant	Mand	Color for Stimulus Cues
Demand fading	Noah	“All done.”	Red
	Liam	“Break please.”	Blue
Dense schedule	Noah	“Break please.”	Blue
	Liam	“All done.”	Red

Functional Analysis Procedures

A functional analysis was conducted to identify the purpose of each child’s challenging behavior. The procedures were based on those described in Iwata, Dorsey, Slifer, Bauman, and Richman (1982/1994), with the addition of the condition of contingent access to tangible items. The therapist interviewed each child’s mother prior to the functional analysis, using a researcher-adapted version of the Functional Analysis Interview (O’Neill et al., 1997), to identify the topographies of challenging behavior and relevant antecedents. Each child’s functional analysis included a play condition and the following test conditions: escape, tangible, and attention. In the play condition, the therapist provided attention at least every 10 s. In each test condition, the therapist arranged relevant antecedent conditions and provided 20 s of access to the relevant consequence contingent on challenging behavior (i.e., escape from demands, access to a highly preferred tangible item, or attention). Each of the sessions was 5 min in length.

Treatment Evaluation Procedures

Baseline

The purpose of the baseline sessions was to evaluate typical rates of challenging behavior. The procedures in the baseline sessions were the same as those in the escape condition of the functional analysis and the first five baseline sessions consisted of the escape condition of the functional analysis. Contingent on challenging behavior, the therapist provided a 20-s break. Contingent on incorrect responding or 5 s without a response, the therapist increased the prompting level according to a least-to-most prompting hierarchy (verbal, verbal plus model, and verbal plus physical prompt). The therapist provided praise contingent on prompted or independent task completion. All other behaviors, including mands, were ignored.

The therapist selected demands for the sessions based on parent or therapist report that the child typically engaged in challenging behavior when presented with the demands. For Noah, demands consisted of preacademic tasks with small manipulative items, such as “Touch green,” “Count,” and “Sort by color.” For Liam, demands consisted of writing letters.

FCT

The therapist taught the child two appropriate, functionally equivalent mands in order to replace challenging behavior with appropriate communication. The target mands were “All done,” and “Break please.” Additional stimulus cues were associated with each of the mands to increase the likelihood that the child would differentiate the different conditions (see Table 1). Specifically, for Noah, the “All done” picture card had a red background (associated with the demand fading condition in the second FCT phase), and the “Break please” picture card had a blue background (associated with the dense schedule condition in the second FCT phase). For Liam, the therapist wore a red T-shirt and taught “All done” (associated with the dense schedule condition in the second and third FCT phases), and the therapist wore a blue T-shirt and taught “Break please” (associated with the demand fading condition in the second and third FCT phases). In the first FCT phase, each of the mands was associated with the same schedule of reinforcement and procedures.

At the beginning of the FCT sessions, the therapist instructed the child to complete one task, then use the target mand. The therapist presented demands at least once every 10 s. The therapist increased the prompt level according to a least-to-most prompting hierarchy (verbal, verbal plus model, and verbal plus physical prompt) with a 5-s time delay between prompts, contingent on noncompliance or incorrect responding. Following the accurate completion of one task without the highest level of prompting, a 20-s break was provided contingent on the independent or prompted use of the target mand. The therapist interacted with the child during the break and provided access to moderately preferred toys. If the child engaged in the target mand prior to meeting the task requirements, the therapist praised the child for asking and restated the contingency. If the child used a nontarget mand during the session, the therapist ignored the mand.

In the initial sessions of FCT, the therapist used a progressive time delay and full verbal model (for Liam) or a full physical prompt with a full verbal model (for Noah) to teach the target mand. The therapist only prompted the target mand following the accurate completion of one task without the highest level of prompting. The time delay started at 0 s and increased by 3 s following three consecutive FCT trials with no challenging behavior. The terminal time delay length was 12 s. Prompting for the mand was terminated once the child engaged in independent mands for 80% or more of the FCT trials in two consecutive sessions for that mand. If the child engaged in challenging behavior, the therapist did not prompt the mand until at least 3 s after the child stopped engaging in challenging behavior in order to avoid incidentally reinforcing the challenging behavior.

Baseline

The second baseline phase followed the same procedures as those in the initial baseline phase.

FCT

In the second FCT phase, the procedures were similar to those in the initial FCT phase. The initial time delay for prompting the mand started at 3 s for this phase. In addition, each of the mands was associated with a different schedule of reinforcement. For Noah, the “Break please” mand was associated with a dense schedule of reinforcement, and the “All done” mand was associated with demand fading. For Liam, the “All done” mand was associated with a dense schedule of reinforcement, and the “Break please” mand was associated with demand fading. The dense schedule of reinforcement condition followed the same procedures as the initial FCT phase. In the demand fading condition, the number of tasks required gradually increased throughout the phase. Specifically, the number of tasks required increased following two consecutive sessions with an 80% decrease in challenging behavior as compared to the average baseline rate. Additionally, prior to the change from one to two tasks, the child also needed to meet the criterion to terminate mand prompting. The following number of tasks was required throughout the phase: (a) one task, (b) two tasks, (c) four tasks, and (d) eight tasks. If the child engaged in the target mand prior to meeting the task requirement, the therapist acknowledged the mand in the same manner as she did in the initial FCT phase. Specifically, the therapist praised the child for asking, restated the contingency, and indicated the number of remaining tasks required. The phase was terminated once the child reached eight tasks and visual analysis indicated a stable pattern of responding for challenging behavior and a decrease in level as compared to baseline.

Extinction

In the extinction sessions, the cues indicating the different conditions (the different T-shirts or different picture cards) were present, but the procedures were the same for all of the extinction sessions. The therapist started the session by indicating that it was time to do work. The therapist presented demands at least once every 10 s. Contingent on incorrect responding or after 5 s without a response, the therapist increased the prompting level according to a least-to-most prompting hierarchy (verbal, verbal plus model, and verbal plus physical prompt). The therapist provided praise contingent on prompted or independent task completion. The therapist acknowledged target mands (e.g., “Thank you for asking. We need to do some more work.”) but did not provide a break contingent on mands. Challenging behavior was ignored during these sessions.

Following the final extinction phase for both participants, the experimenters met with the participants’ parents and provided recommendations. For both participants, the experimenters recommended using the structured prompting sequence, increasing task demands until the child achieved a predetermined goal, and continuing the reinforcement of mands. Therefore, although the study ended on an extinction phase, the experimenters promoted the continued use of the intervention following the completion of the study.

Additional FCT and Extinction Phases (Liam Only)

During the initial extinction phase, Liam engaged in challenging behavior during both conditions. For this reason, the experimenters decided to implement an additional FCT phase, during which the response requirement was increased from 8 demands to 16 demands in the demand fading condition. All other procedures were the same as those in the previous FCT phase. Following the third FCT phase, the therapist implemented extinction again, using the same procedures as those in the previous extinction condition.

Treatment Fidelity

To assess the accuracy of therapist implementation, an independent observer collected treatment fidelity data during at least 30% of the sessions within each phase and for each participant. The observer used a researcher-developed task analysis of the procedures to rate the implementer as correct or incorrect for each step during the session. The number of steps implemented correctly was converted to a percentage of steps implemented correctly (i.e., the number of steps implemented correctly divided by the total number of steps multiplied by 100). The average treatment fidelity was 99.1% (range 88%–100%) for Noah’s sessions and 99.6% (range 90%–100%) for Liam’s sessions.

Results

Functional Analysis

The functional analyses indicated that the function of each participant’s challenging behavior was escape from demands (see Fig. 1). For Noah, the escape condition was associated with the highest rate of challenging behavior (M = 1.52, range 0.00–3.20). Challenging behavior occurred at a lower rate in the attention (M = 0.08, range 0.00–0.40) and tangible conditions (M = 0.12, range 0.00–0.60). No challenging behavior occurred during the play (control) condition. Liam engaged in challenging behavior during the escape condition (M = 0.34, range 0.00–0.50) and did not engage in any instances of challenging behavior during the attention, tangible, or play conditions.

Fig. 1.

Responses per minute of aggression during functional analysis for Noah (top panel) and Liam (bottom panel)

Treatment Evaluation

FCT was associated with a decrease in challenging behavior for both participants (see Figs. 2 and 3). The challenging behavior results varied by participant in the extinction condition. Similarly, FCT was associated with an increase in mands for both participants, but the persistence of mands during the extinction condition varied by participant. Noah’s treatment was 1 month and Liam’s treatment was 3.5 months from the initial FCT session to the final FCT session.

Fig. 2.

Responses per minute of aggression (top panel), independent mands (middle panel), and task completion (bottom panel) for Noah. An asterisk indicates an increase in the number of demands required

Fig. 3.

Responses per minute of aggression (top panel), independent mands (middle panel), and task completion (bottom panel) for Liam. An asterisk indicates an increase in the number of demands required

Noah

For Noah, the initial baseline data were variable, with an increasing trend in challenging behavior at the end of the phase (M = 1.90, range 0.00–3.80). In the subsequent FCT phase, the procedures were the same across both conditions, and both conditions were associated with a decrease in the level of challenging behavior (demand fading: M = 0.16, range 0.00–0.40; dense schedule: M = 0.28, range 0.00–0.80). There was a level increase and an increasing trend in challenging behavior during the second baseline phase (M = 1.50, range 0.40–2.20). During the initial two sessions of the second FCT phase, Noah engaged in elevated rates of challenging behavior, but challenging behavior decreased to zero instances in the final sessions of the phase. During this phase, Noah engaged in similar rates of challenging behavior during both the demand fading (M = 0.37, range 0.00–3.6) and the dense schedule conditions (M = 0.34, range 0.00–4.2). Together, the first four phases included three demonstrations of effect, indicating a functional relation between FCT and a decrease in challenging behavior. In the extinction phase, Noah did not engage in any challenging behavior in the demand fading or dense schedule contexts (with differing stimulus cues but the same procedures), indicating that challenging behavior did not resurge following FCT. The data indicated that Noah completed work without engaging in challenging behavior. However, it was important that Noah continue to mand for breaks in circumstances in which the establishing operation for escape-maintained behavior was present. For this reason, the experimenters recommended that Noah’s parents, teachers, and therapists continue to reinforce the mands following the completion of the study.

Noah did not mand independently during the baseline sessions in either baseline phase. However, FCT was associated with higher rates of mands than the baseline phases were, and mands persisted during the extinction phase in both conditions. During the initial FCT phase, in which the procedures were the same across both conditions, Noah engaged in similar rates of manding in both the demand fading (M = 0.56, range 0.20–1.00) and dense schedule (M = 0.40, range 0.00–1.00) conditions. These data suggest that there was no difference in responding across stimuli when the contingencies were the same. In the second FCT phase, Noah manded at a higher rate during the demand fading condition (M = 1.25, range 0.20–2.40) as compared to the dense schedule condition (M = 0.97, range 0–1.80), especially during the end of the phase as the demand requirement increased. The level difference and trend difference at the end of the phase suggest differentiation between the data paths. In the extinction phase (with the same procedures across conditions and different stimulus cues), Noah engaged in similar rates of mands in the demand fading (M = 0.64, range 0.40–1.00) and dense schedule (M = 0.56, range 0.00–1.20) conditions. The similar level and trend indicate that there was no differentiation between the two conditions but that there was a decreasing trend in both conditions.

For Noah, FCT was associated with an increase in task completion as compared to baseline conditions. In addition, task completion persisted at similar rates to the FCT phases during the extinction phase. Task completion increased from the initial baseline (M = 0.57, range 0.00–1.60) to the initial FCT phase (demand fading: M = 0.96, range 0.80–1.00; dense schedule: M = 0.80, range 0.60–1.00), indicating that Noah’s behavior was similar across stimuli during the phase in which the contingencies were the same across stimuli. In the second baseline phase, there was a decrease in task completion (M = 0.50, range 0.00–1.60). The final FCT phase was associated with a level increase in both conditions, and Noah completed tasks at a higher rate during the demand fading condition (M = 2.18, range 0.40–3.80) than during the dense schedule condition (M = 1.00, range 0.20–1.40). The level and trend in each condition indicate differentiation between the conditions, suggesting that demand fading resulted in higher rates of task completion. Finally, the level of task completion increased in the extinction phase in both the demand fading (M = 3.08, range 2.40–4.20) and dense schedule conditions (M = 3.04, range 2.60–3.80). However, there was a decreasing trend in task completion during the extinction phase in both conditions.

Liam

For Liam, FCT was associated with decreases in challenging behavior. Challenging behavior resurged during extinction sessions but occurred at lower rates than during the baseline phases. In the initial baseline, there was an increasing trend in challenging behavior (M = 0.34, range 0.00–0.50). In the initial FCT phase, in which the procedures were the same across both conditions, there was a level decrease in both conditions (demand fading: M = 0.10, range 0.00–0.30; dense schedule: M = 0.05, range 0.00–0.10). The second baseline phase was associated with an increase in challenging behavior (M = 0.88, range 0.40–1.40). During the subsequent FCT phase, Liam’s challenging behavior decreased to similarly low rates in both the demand fading (M = 0.10, range 0.00–0.30) and dense schedule conditions (M = 0.04, range 0.00–0.30). In the first extinction phase (in which the procedures were the same across conditions, but the stimulus cues differed), Liam engaged in higher rates of challenging behavior than in the previous FCT phase. He engaged in similar rates of challenging behavior in both the demand fading (M = 0.20, range 0.00–0.80) and dense schedule conditions (M = 0.21, range 0.00–0.70). In the final FCT phase, Liam engaged in low levels of challenging behavior in both the demand fading (M = 0.10, range 0.00–0.30) and dense schedule conditions (M = 0.01, range 0.00–0.10). In the final extinction phase (in which the procedures were the same across conditions, but the stimulus cues differed), Liam’s challenging behavior returned to rates similar to the previous extinction condition but was below baseline levels (demand fading: M = 0.23, range 0.00–0.50; dense schedule: M = 0.13, range 0.00–0.40). Because Liam continued to engage in challenging behavior during the extinction conditions, the experimenters recommended continued use of the intervention at home and in his typical applied behavior analysis sessions at the private clinic he attended.

FCT was associated with higher rates of mands and independent task completion relative to baseline. However, mands did not persist during the extinction conditions for Liam. Liam did not mand during either baseline phase. In the initial FCT phase (with the same procedures across conditions), mands occurred at a lower rate on average in the demand fading condition (M = 0.82, range 0.00–1.10) as compared to the dense schedule condition (M = 1.18, range 0.80–1.60). However, due to the variability and overlap in the data paths, there did not appear to be a consistent change in manding in the presence of the two different sets of stimuli during the phase with the same contingencies across stimuli. During the second FCT phase, Liam manded at a higher rate during the dense schedule condition (M = 1.14, range 0.90–1.50) as compared to the demand fading condition (M = 0.81, range 0.30–1.30). The decreasing trend in the demand fading condition indicated differentiation between the two data paths, suggesting that demand fading was associated with fewer independent mands than the dense schedule condition was. During the first extinction condition (in which the procedures were the same across conditions, but the stimulus cues differed), Liam engaged in few mands during the demand fading condition (M = 0.04, range 0.00–0.20) and no mands during the dense schedule condition. The final FCT phase was associated with a consistently higher rate of mands during the dense schedule condition (M = 1.27, range 1.10–1.40) than the demand fading condition was (M = 0.06, range 0.00–0.20). The differentiation in the data paths throughout the phase indicates a functional relation between the dense schedule condition and a higher rate of mands. In the final extinction phase (in which the procedures were the same across conditions, but the stimulus cues differed), Liam did not mand during the demand fading condition and engaged in few mands during the dense schedule condition (M = 0.05, range 0.00–0.20).

FCT was associated with an increase in task completion as compared to baseline rates. In addition, task completion persisted at higher rates than in baseline during the extinction sessions. In the initial baseline phase, task completion was variable, and there was a decreasing trend in the data (M = 0.56, range 0.00–0.90). In the initial FCT phase, Liam engaged in similar rates of task completion in the demand fading (M = 1.00, range 0.80–1.30) and dense schedule conditions (M = 1.03, range 0.90–1.20). These data suggest that given the same contingencies, Liam engaged in similar rates of task completion under the two different stimulus conditions. The data in the second baseline phase were similar to those in the first baseline phase (M = 0.57, range 0.30–1.20). In the second FCT phase, the dense schedule condition was associated with a lower rate of task completion (M = 1.13, range 1.00–1.40) than the demand fading condition was (M = 2.28, range 0.80–3.90). Visual analysis of the data shows consistently low levels for the dense schedule condition and an increasing trend for the demand fading condition. Task completion persisted during the first extinction phase (in which the procedures were the same across conditions, but the stimulus cues differed), with higher task completion in the demand fading condition (M = 1.50, range 0.80–2.20) than in the dense schedule condition (M = 1.09, range 0.70–1.90). There was differentiation between the two data paths in this phase, with a decreasing trend in both data paths. In the third FCT phase, the demand fading condition was associated with slightly lower rates of task completion (M = 1.00, range 0.30–1.80) than the dense schedule condition was (M = 1.27, range 1.10–1.40). In addition, there was a decreasing trend in task completion in the demand fading condition, especially after the onset of the 16-demand requirement. However, across the second and third FCT phases, the average rate of task completion was higher in the demand fading condition (M = 1.81) than in the dense schedule condition (M = 1.18). In the final extinction phase (in which the procedures were the same across conditions, but the stimulus cues differed), there was a decreasing trend in the dense schedule condition (M = 0.98, range 0.20–1.50), and the rate of task completion was slightly lower than the in demand fading condition (M = 1.18, range 0.80–1.80). However, there was little differentiation between the data paths in this phase.

Percentage of Accurate Mands

As a secondary analysis, the experimenters evaluated the percentage of accurate mands during the FCT phases in which the demand fading and dense schedules were compared (see Fig. 4). The experimenter counted the mand as accurate if it occurred following the completion of the task requirement and as inaccurate if it occurred prior to the completion of the task requirement. The experimenters calculated the percentage of accurate mands using the following formula: the number of target mands emitted after completing the task requirement (i.e., accurate mands) divided by the total number of target mands multiplied by 100.

Fig. 4.

Percentage of accurate mands during the second and third FCT phases for Noah (top panel) and Liam (bottom panel). An asterisk indicates an increase in the number of demands required

Noah

For Noah, 48% of mands were accurate in the demand fading condition (42 of 88 mands), and 94% were accurate in the dense schedule condition (63 out of 67 mands). These data indicate that mands for escape were on an intermittent schedule during the demand fading condition.

Liam

In the second FCT phase, 98% of Liam’s mands were accurate in the demand fading condition (95 out of 97 mands), and 100% of mands were accurate in the dense schedule condition (137 out of 137 mands). In the third FCT phase, 86% of mands were accurate in the demand fading condition (6 out of 7 mands), and 98% of mands were accurate in the dense schedule condition (89 out of 91 mands). Overall, these data indicate that mands for escape typically resulted in reinforcement for Liam, with nearly every emitted target mand resulting in reinforcement during the two FCT phases.

Percentage of Correct Responses

The experimenters also reviewed the number of demands presented and the percentage of opportunities with task completion in each condition to evaluate if either of these variables contributed to differences in task completion across the conditions. In the second FCT phase for Noah, there was an average of 11.31 demands per session during the demand fading condition and 5.46 demands per session in the dense schedule condition. Noah completed tasks during 94% and 92% of opportunities in the demand fading and dense schedule conditions, respectively. Across the second and third FCT phases for Liam, there was an average of 27.53 demands per session in the demand fading condition and 13.53 demands per session in the dense schedule condition. In the second FCT phase, Liam’s percentage of opportunities with task completion was comparable across the conditions: 87% and 85% for demand fading and dense schedule, respectively. In the third FCT phase, the percentage of opportunities with task completion was much lower in the demand fading condition (32%) than in the dense schedule condition (94%). Together, these data indicate that for the two phases with higher task completion in the demand fading condition, the higher task completion was due to an increase in the number of opportunities to complete tasks rather than an increase in the percentage of opportunities with task completion.

Discussion

The purpose of this study was to evaluate the impact of demand fading on escape-maintained challenging behavior, mands, and task completion during and following FCT. Two children with autism were included in the study. The treatment evaluation indicated FCT was effective at reducing challenging behavior for both participants. There was little to no difference in the rate of challenging behavior across the demand fading and dense schedule conditions for either participant. Demand fading was associated with an increase in the rate of task completion for both participants as compared to the dense schedule of reinforcement. The effect of demand fading on mands differed by participant, with one participant engaging in a higher rate of mands during the demand fading condition and the other participant engaging in a higher rate of mands during the dense schedule condition.

Research Question 1: Does Demand Fading Result in the Reduction of Escape-Maintained Challenging Behavior During the Intervention as Compared to a Dense Schedule of Reinforcement?

The demand fading and dense schedule conditions were associated with similarly low rates of challenging behavior for both participants. These data indicate that both the dense schedule and the demand fading conditions produce reductions in challenging behavior as compared to baseline and that neither condition produces a larger reduction in challenging behavior. Practically, these data indicate that implementers can expect similar reductions in challenging behavior across these conditions but that the demand fading procedure may result in higher rates of task completion. These findings were similar to findings in Hagopian et al.’s (2004) study, which found that both a dense-to-lean schedule and a fixed-lean schedule resulted in reductions in challenging behavior. These results also extend previous research conducted by Wacker et al. (2011, 2013) by directly comparing the rate of appropriate behaviors during different treatment conditions.

Research Question 2: Does Demand Fading Result in an Increase in Task Completion During the Intervention as Compared to a Dense Schedule of Reinforcement?

A common concern regarding the use of FCT is that it is likely to produce too frequent access to function-based reinforcement at the expense of instructional time (Tiger et al., 2008). Demand fading resulted in a higher rate of task completion for both participants than the dense schedule condition did. These data indicate that the demand fading condition may be preferable to the dense schedule condition because the child is likely to complete more tasks, which will lead to more rapid improvements in skills. The review of the number of demands presented per condition indicated that the difference in the rate of demand completion was due to the number of demands presented during the sessions. These data suggest that demand fading provides more opportunities for task completion, rather than increasing correct responding.

Liam’s rate of task completion and percentage of opportunities with task completion decreased during the demand fading condition of the third FCT phase, in which the demand requirement was 8 or 16 demands prior to receiving a break. He also completed a lower percentage of demands presented during the demand fading condition than he did in the dense schedule condition. The rapid increase in the number of demands required may have caused the decrease in task completion during the third FCT phase. The magnitude of the reinforcement may have been insufficient to maintain the high response requirement (Roane, Falcomata, & Fisher, 2007). Liam’s data in the third FCT phase suggest the need for additional research regarding the criterion for increasing the demand response requirement. Future research should also investigate the extent to which similar patterns of responding occur for other children at higher response requirements and should evaluate methods to promote increased independent task completion even during higher response requirements.

Research Question 3: Does Demand Fading Result in a Decrease in Mands During the Intervention as Compared to a Dense Schedule of Reinforcement?

The condition associated with the higher rate of manding differed by participant. Our hypothesis was that the demand fading condition would be associated with lower rates of mands due to the chained schedule. However, this was only the case for one of the two participants. For the other participant, the rate of manding was higher for the demand fading condition than it was in the dense schedule condition. The secondary analysis indicated that Liam’s mands contacted reinforcement on a schedule that was close to a continuous schedule of reinforcement and that Noah’s mands contacted reinforcement on an intermittent schedule during the demand fading condition. The intermittent schedule of reinforcement for Noah may have resulted in higher rates of mands in the demand fading condition and a higher persistence of mands during the extinction phases (Stephens, Pear, Wray, & Jackson, 1975). However, the schedule of reinforcement of mands was not systematically manipulated, so it is unclear whether the schedule of reinforcement for mands affected the rate.

Research Question 4: Does Demand Fading Result in a Reduced Resurgence of Challenging Behavior as Compared to a Dense Schedule of Reinforcement?

There was no clear differentiation between the demand fading and dense schedule contexts in the extinction phases, indicating no demonstrated effect of demand fading on the resurgence of challenging behavior. Previous literature suggests that demand fading, along with multiple exposures to extinction and long-term implementation of FCT, results in a reduced resurgence of challenging behavior (Wacker et al., 2011, 2013). The data from this study align with previous research in that the children’s challenging behavior was lower than baseline levels during extinction conditions. However, the extent to which demand fading resulted in a reduction in resurgence was unclear due to the lack of differentiation during extinction phases. These data also align with previous research that indicates challenging behavior tends to resurge under extinction conditions following a variety of different intervention components, with very few of the previous participants engaging in zero challenging behavior under extinction conditions (Radhakrishnan et al., 2019). Noah did not engage in challenging behavior during the extinction phase for either condition. Demand fading during FCT may have resulted in Noah engaging in no challenging behavior during the extinction phase. However, there was no differentiation in the rate of challenging behavior between the demand fading and dense schedule contexts. It may be the case that demand fading or another intervention component resulted in the decrease in challenging behavior during the extinction phases, but these results do not clearly indicate which variables led to the lack of resurgence. Liam engaged in challenging behavior in both contexts during the extinction phases, suggesting that the intervention procedures did not prevent the resurgence of challenging behavior for Liam.

Liam and Noah engaged in differing patterns of challenging behavior during the treatment conditions, which may have contributed to the differing resurgence of challenging behavior under extinction conditions. Liam engaged in zero instances of challenging behavior during 63% and 64% of sessions in the second and third FCT phases, respectively. Noah engaged in zero instances of challenging behavior during 85% of sessions in the second FCT phase. The researchers followed the same criterion to move to the extinction phase for both participants, but it was not based on the number of sessions with zero instances of challenging behavior, allowing for some differences across participants. It is unclear if the occurrence of challenging behavior during this phase contributed to the rate of challenging behavior during the extinction phases. However, the findings from this study do suggest the need for additional research regarding the extent to which more sessions with zero challenging behavior during the intervention phase contribute to a reduced resurgence under extinction conditions.

It is important to note that it is not recommended to end on an extinction phase in practice. The purpose of the extinction phase in this study was to evaluate the resurgence of challenging behavior. Based on previous research (e.g., Wacker et al., 2011, 2013), practitioners should promote long-term implementation of FCT with children who engage in escape-maintained challenging behavior. For the participants included in this study, the experimenters met with the parents and recommended the continued reinforcement of the mands, the use of schedule thinning, and the use of structured prompting to promote the implementation of the intervention following the study.

Limitations

The results of the present study should be interpreted with caution, given its limitations. This study included two participants. The data and design demonstrated the efficacy of FCT. However, there was no differentiation for the challenging behavior dependent variable for either participant. The lack of differentiation for the challenging behavior dependent variable may have been due to carryover effects between the two conditions. Future research should consider utilizing a different design to evaluate the effect of demand fading on challenging behavior. Although these data do not provide evidence for the effect of demand fading on the occurrence of challenging behavior during the session, the rate of task completion and mands did vary by condition, providing information about the effect of demand fading on these dependent variables.

Two mands were taught during the FCT phase. If the child engaged in the mand associated with the other condition (e.g., he said “All done” rather than “Break please”), the mand was ignored (i.e., extinction). This may have affected the results of the study. However, this only occurred three times throughout the study; Noah said the incorrect mand once in the demand fading condition and twice in the dense schedule condition.

The number of demands presented varied by condition, which led to the difference in the rate of task completion in each condition. The more frequent breaks in the dense schedule condition likely caused the lower number of demands in that condition, and the experimenters did not control for the number of demands presented in each condition. Instead, the experimenters kept the length of the session consistent across the two conditions. These procedures provide information about the number and rate of completed tasks for each procedure, given a specific time constraint. Practitioners (e.g., teachers, therapists) typically have a set amount of time allocated to work with a child. Therefore, this study provides practical information about the relative number of tasks completed given a particular time constraint. However, future research should further investigate the extent to which demand fading affects the percentage of accurate responses given the same number of demands in each condition. In addition, future research should evaluate the difference in the length of time required to provide the same number of demands across the two conditions given the frequent breaks in the dense schedule condition.

Finally, some of the included procedures may not reflect typical practice. The short 5- or 10-min sessions may limit the generalizability of these findings to longer sessions. In addition, study procedures, such as teaching two distinct mands, using stimuli to indicate the condition, and rapid alternation between conditions, may have influenced the results. Based on these limitations, there is a need for replication of these results in contexts that more closely align with typical practice.

Directions for Future Research

Based on the present findings, there are a number of important directions for future research. First, future research should evaluate demand fading in natural settings with typical implementers (e.g., Wacker et al., 2011, 2013). For example, challenging behavior may occur at different rates under intervention and extinction conditions in a classroom as compared to a clinical setting. It is important to investigate the variables that affect rates of challenging behavior in clinical, school, home, and community settings. Future research should further evaluate the extent to which the increased rate of task completion diminishes as the demand requirement increases. In addition, there is a need for further research on the variables that result in higher or lower rates of mands under demand fading conditions as compared to dense schedule conditions. Finally, future research should continue to evaluate the effect of specific intervention variables, such as the schedule of reinforcement for mands, on the resurgence of challenging behavior following the intervention.

Implications for Practice

The data from the present study provide further evidence for the efficacy of FCT in reducing escape-maintained challenging behavior in children with ASD. In addition, the data from the present study suggest that demand fading is associated with a higher rate of task completion. This represents a relative benefit of demand fading for use in practice as compared to the dense schedule of reinforcement. Both the demand fading condition and the dense schedule condition resulted in a reduction in challenging behavior during the FCT phase. Due to the increased task completion and the decreased frequency of breaks, it is likely that demand fading is more feasible and socially valid for use in applied settings than a continued dense schedule of reinforcement is. Finally, it is important to note that FCT with demand fading may not be sufficient to reduce the reoccurrence of challenging behavior. Based on previous research and the present results, practitioners should encourage the continued implementation of FCT over extended periods of time, to the extent possible, to prevent the reoccurrence of challenging behavior.

Author Note

Stephanie Gerow, Department of Educational Psychology, Baylor University Waco, Texas; Supriya Radhakrishnan, Department of Educational Psychology, Baylor University; Tonya N. Davis, Department of Educational Psychology, Baylor University Waco, Texas; Abby Hodges, Department of Teaching and Learning Sciences, University of Denver CO; Amy Feind, Northwest Independent School District Fort Worth, TX.

The authors would like to thank Gabby Rivera, Christy Prawira, Nicole O’Guinn, and Lauren Uptegrove for their assistance with data collection.

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from parents/legal guardians of all individual participants included in the study.