The Prevalence of Preference Displacement of Leisure Items by Edible Stimuli In Children with Autism

Background: The identification of preferred stimuli is a critical aspect of successful treatment strategies for children with autism. Preferred stimuli are frequently used to shape or teach new adaptive behaviors or in programming to reduce maladaptive behavior. The paired-stimulus (PS) preference assessment developed by Fisher et al., (1992) constitutes one commonly used assessment method for creating a hierarchy of preferred items. In a PS, several stimuli are presented in pairs and an observer records the number of times the individual selects each item. Presentations are repeated until every item has been presented in a pair with every other item. The item selected most frequently is determined to be the most preferred. Studies have indicated that individuals often select edible stimuli instead of leisure items when compared during preference assessments (DeLeon, Iwata, & Roscoe, 1997; Bojak & Carr, 1999). This result suggests that edible stimuli may serve as more effective reinforcers compared to leisure items. However, the prevalence of displacement of leisure items by edible stimuli with children with autism is unclear. Additionally, the influence of reinforcer magnitude during a PS and delays on displacement is unknown. That is, most preference assessments present choices between one portion of an edible item and an arbitrary duration of access to a leisure item (e.g., 30 seconds). Displacement may be a product of the relatively brief periods of access to leisure items.

Objectives: The purpose of the current investigation was to examine the prevalence of displacement of leisure items in children with autism, and to determine whether duration of access to leisure items affects displacement.

Methods: In Experiment 1, 26 participants were exposed to three PS assessments that evaluated edible stimuli, leisure items, and the two combined. Results of the combined PS were compared to those of the two separated assessments to determine whether displacement occurred. In Experiment 2, participants chose between edible stimuli that displaced leisure items and the most preferred leisure item. The duration of access to the leisure item was then systematically increased across series to identify the point at which leisure items became more preferred. That is, as the duration of access to an item increases, a shift in preference to the leisure item emerges.

Results: Results of Experiment 1 indicate that for 20 of the 26 participants (77.0%) the most frequently selected item was food. Additionally, for 14 of the 26 participants (54.0%) the three highest ranked items were edible stimuli. During Experiment 2, the leisure stimulus eventually displaced all of the edible stimuli following increases in duration of access.

Conclusions: The current study suggests that the displacement of leisure items is common amongst children with autism. Additionally, the displacement of leisure items by edible stimuli during PS is likely influenced by the duration of access to the leisure item. Thus, it is important for clinicians who may use leisure items as reinforcers to consider the influence of particular dimensions of reinforcement (i.e., magnitude) on preference and reinforcer efficacy.