Investigating the Use of a Blocked Trial Procedure to Facilitate Conditional Discriminations Nicholas K. Reetz, Paula Petit, Sarah Camp, Valerie VanTussi, Brianne Larson, & Kevin P. Klatt Psychology Department, University of Wisconsin-Eau Claire Method Introduction Results Support for this project came both from the Office of Research and Sponsored Programs and from Differential Tuition through the UWEC Student Travel for the Presentation of Research Results Program. Discussion A skill repertoire is a set of skills that share several attributes. For example, correctly following the instructions “touch nose,” “touch head,” “touch belly,” and “touch foot” all fall into the skill repertoire of being able to touch body parts when instructed to do so. Behavioral therapists, who use behavioral principles to teach skills, typically teach one skill within a behavior repertoire to mastery before teaching another skill within the same repertoire. A fairly common problem exhibited by children with profound cases of autism is the inability to consistently and correctly discriminate between previously isolated skills from a developing repertoire when instructions to perform those skills are randomized. Little to no research addresses how to teach the ability to discriminate to young children with autism who are in the process of building simple skill repertoires (e.g., motor imitation, receptive identification of body parts, etc.). The inability to discriminate can significantly slow the acquisition of new skills in a child's developing repertoire and may be attributed to a lack of stimulus control. The current study investigated the use of a blocked trial procedure (Saunders & Spradlin, 1993) to facilitate conditional skill discriminations. The participant was a 4.5 year old girl diagnosed with autism spectrum disorder. Experimental sessions were run during normally scheduled therapy sessions. Skills were taught in isolation of one another by the participant’s therapy team before the discrimination between the skills was taught. Sessions were terminated if severe problem behavior occurred or if the participant made six consecutive errors. The participant was taught to discriminate between two sets of skills, with each set consisting of two skills: Discrimination Set 1: Skill 1 = Touch Nose; Skill 2 = Touch Foot Discrimination Set 2: Skill 1 = Touch Belly; Skill 2 = Touch Head 18 trials were scheduled to be presented for each discrimination set being run. Incorrect responses were not followed by a correction procedure. Baseline data indicated that the participant could not discriminate between the skills in each skill set. In Discrimination Set 1, the participant took nearly one month to meet the mastery criteria for Block Type 3. In Discrimination Set 2, the participant took two days to meet the mastery criteria for Block Type 3. The participant was able to meet mastery criteria in less sessions as she progressed through block types in Discrimination Set 1. Data taken from the terminal condition probes in Discrimination Set 1 displayed an upward trending curve. In Discrimination Set 1, the participant met the percentage correct specified by the mastery criteria on a Block Type 8 probe after Block Type 6. In Discrimination Set 2, the participant met the percentage correct specified by the mastery criteria on a Block Type 8 probe after Block Type 4. The sole use of a blocked trial procedure does not appear to immediately establish effective stimulus control of an instruction over a response. Supplemental methodological adjustments (e.g., the use of a preceding maintenance probe, the use of vocal prompts, etc.) appear necessary to effectively establish initial stimulus control of an instruction over a response. No supplemental methodological adjustments were needed to maintain effective stimulus control after the most basic discrimination task (i.e., Block Type 3) had been mastered. As shown by the upward trending curve of the Block Type 8 probe data points in Discrimination Set 1, the participant was better able to complete difficult discrimination tasks (i.e., Block Type 8) after mastering easier discrimination tasks. The acquisition of the ability to discriminate between two skills (i.e., Discrimination Set 2) appears to occur more rapidly after the mastery of previously taught discriminations (i.e., Discrimination Set 1). The ability to discriminate between two skills, as taught by the use of a blocked trial procedure, appears to maintain in general. If a loss of the ability to discriminate between two skills occurs, re-applying the blocked trial procedure appears to re- establish the ability to discriminate. Trial: Establishment of Motivating Operation *All responses in baseline sessions were followed by no scheduled consequences. Instruction Correct Response Receipt of Reinforcer Instruction Incorrect Response No consequence Block Types: Baseline = randomized trials of skills 1 and 2 Block Type 1 = 18-trial block of skill 1 Block Type 2 = 18-trial block of skill 2 Block Type 3 = 9-trial blocks of skills 1 and 2 Block Type 4 = 6-trial blocks of skills 1 and 2 Block Type 5 = 4-trial blocks of skills 1 and 2 Block Type 6 = 3-trial blocks of skills 1 and 2 Block Type 7 = randomized 2-trial, 3-trial, and 4-trial blocks of skills 1 and 2 Block Type 8 = randomized trials of skills 1 and 2 *The criteria needed to progress to the next scheduled block type was correct responding to at least 85% of trials presented across two consecutive days. Maintenance Probe: Establishment of Motivating Operation Instruction Correct Response Begin 18 trial experimental session Occurred directly before 18 trial experimental session Incorrect Response Two prompted trials Begin 18 trial experimental session Block Type 8 (Terminal Condition) Probe: Probes occurred on sessions following the meeting of mastery criteria for a discrimination block type. Followed typical trial format. This manipulation allowed the researchers to track the participant’s ability to discriminate between randomly presented trials.