Single- vs. combined-category preference assessments for edible, leisure, and social-interaction stimuli

A concern when conducting combined-category preference assessments is the potential for displacement effects, a shift in the preference ranking from highly preferred to moderately or less preferred for stimuli in two of three stimulus categories (e.g., edible, leisure, or social-interaction). In this study, we evaluated potential displacement effects in combined-category arrays of edible, leisure, and social-interaction stimuli for five individuals with autism. First, single-category paired-stimulus preference assessments were implemented to identify two highly preferred stimuli from each category. When these stimuli were included in a combined-category preference assessment, displacement effects were observed for three of five participants. During a subsequent reinforcer assessment, stimuli identified as less preferred in the combined-category preference assessment functioned as reinforcers for two participants. Additionally, although social interaction was not identified as highly preferred for three of the five participants, it functioned as a reinforcer for four participants.