Expansion of Sidman's theory: The inclusion of prompt stimuli in equivalence classes.

Stimulus equivalence is defined as the ability to relate stimuli in novel ways after training in which not all of the stimuli had been directly linked to one another. Sidman (2000) suggested all elements of conditional discrimination training contingencies that result in equivalence potentially become class members. Research has demonstrated the inclusion of samples, comparisons, responses, and reinforcers in equivalence classes. Given the evidence that all elements of a conditional discrimination become part of the class, the purpose of this study was to determine if class-specific prompts would also enter into their relevant equivalence classes. Experiment 1 investigated the inclusion of prompts in an equivalence class using abstract stimuli with neurotypical students enrolled in higher education courses. Experiment 2 systematically replicated Experiment 1 using meaningful stimuli and individuals diagnosed with autism spectrum disorder. The results of both experiments demonstrated that class-specific prompts became part of equivalence classes with the other positive elements of the contingency. The results are discussed in terms of class expansion and the potential impact on equivalence-based instruction.

Sleep patterns predictive of daytime challenging behavior in individuals with low-functioning autism.

Increased severity of problematic daytime behavior has been associated with poorer sleep quality in individuals with autism spectrum disorder. In this work, we investigate whether this relationship holds in a real-time setting, such that an individual's prior sleep can be used to predict their subsequent daytime behavior. We analyzed an extensive real-world dataset containing over 20,000 nightly sleep observations matched to subsequent challenging daytime behaviors (aggression, self-injury, tantrums, property destruction and a challenging behavior index) across 67 individuals with low-functioning autism living in two U.S. residential facilities. Using support vector machine classifiers, a statistically significant predictive relationship was found in 81% of individuals studied (P < 0.05). For all five behaviors examined, prediction accuracy increased up to approximately eight nights of prior sleep used to make the prediction, indicating that the behavioral effects of sleep may manifest on extended timescales. Accurate prediction was most strongly driven by sleep variability measures, highlighting the importance of regular sleep patterns. Our findings constitute an initial step towards the development of a real-time monitoring tool to pre-empt behavioral episodes and guide prophylactic treatment for individuals with autism. Autism Res 2018, 11: 391-403. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We analyzed over 20,000 nights of sleep from 67 individuals with autism to investigate whether daytime behaviors can be predicted from prior sleep patterns. Better-than-chance accuracy was obtained for 81% of individuals, with measures of night-to-night variation in sleep timing and duration most relevant for accurate prediction. Our results highlight the importance of regular sleep patterns for better daytime functioning and represent a step toward the development of 'smart sleep technologies' to pre-empt behavior in individuals with autism.

Behaviorally-determined sleep phenotypes are robustly associated with adaptive functioning in individuals with low functioning autism.

Despite sleep disturbance being a common complaint in individuals with autism, specific sleep phenotypes and their relationship to adaptive functioning have yet to be identified. This study used cluster analysis to find distinct sleep patterns and relate them to independent measures of adaptive functioning in individuals with autism. Approximately 50,000 nights of care-giver sleep/wake logs were collected on school-days for 106 individuals with low functioning autism (87 boys, 14.77 ± 3.11 years) for 0.5-6 years (2.2 ± 1.5 years) from two residential schools. Using hierarchical cluster analysis, performed on summary statistics of each individual across their recording duration, two clusters of individuals with clearly distinguishable sleep phenotypes were found. The groups were summarized as 'unstable' sleepers (cluster 1, n = 41) and 'stable' sleepers (cluster 2, n = 65), with the former exhibiting reduced sleep duration, earlier sleep offset, and less stability in sleep timing. The sleep clusters displayed significant differences in properties that were not used for clustering, such as intellectual functioning, communication, and socialization, demonstrating that sleep phenotypes are associated with symptom severity in individuals with autism. This study provides foundational evidence for profiling and targeting sleep as a standard part of therapeutic intervention in individuals with autism.

Membership of Defined Responses in Stimulus Classes.

Sidman (2000) has suggested that in addition to conditional and discriminative stimuli, class-consistent defined responses can also become part of an equivalence class. In the current study, this assertion was tested using a mixed-schedule procedure that allowed defined response patterns to be "presented" as samples in the absence of different occasioning stimuli. Four typically developing adults were first trained to make distinct response topographies to two visual color stimuli, and then were taught to match those color stimuli to two different form-sample stimuli in a matching task. Three separate tests were given in order to determine whether training had established two classes each comprised of a response, a color, and a form: a form-response test in which the forms were presented to test if the participants would make differential responses to them; and two response-matching tests to test if the participants would match visual stimulus comparisons to response-pattern samples. Three of the four participants showed class-consistent responding in the tests, although some participants needed additional training prior to passing the tests. In general, the data indicated that the different response patterns had entered into a class with the visual stimuli. These results add to a growing literature on the role of class-consistent responding in stimulus class formation, and provide support for the notion that differential responses themselves can become a part of an equivalence class.