Choice with frequently changing food rates and food ratios

Secondary and within-session analyses to improve the feasibility and precision of assessments of sociability

Previous research has improved the feasibility and precision of assessments of sociability, but further progress is warranted. The purpose of this study was to evaluate secondary measures and within-session analyses to further improve the feasibility and precision of assessments of sociability. We reanalyzed previously published assessment results to evaluate whether initial and conditional (i.e., on therapist movement) approach and avoidance may approximate established continuous measures. Results indicated that both measures were strongly correlated with the percentage of session on the social side and may provide a more feasible approximation for use in clinical practice. We also conducted within-session analyses of these assessment results to evaluate whether they may improve precision or clarity. Correlational and matching-based analyses of the within-session data suggest that clear conclusions may be drawn from the results of a single session and facilitate a richer understanding of sociability. Implications for clinical practice and future research are discussed.

The matching law provides a quantitative description of social time allocation in children with autism

Recent research has developed and evaluated assessments of sociability in which time allocation near or away from an adult who initiates social interactions is used to characterize the participant as social, indifferent, or avoidant of social interaction. Though these qualitative outcomes have been useful, no studies have evaluated methods of obtaining more quantitative measures of sociability. The matching law has been demonstrated to describe a wide range of human behavior and may also be useful in describing social time allocation. We adapted the matching law and assessment of sociability procedures with the aim of providing a more precise, quantitative measure of sociability. We fitted the matching equation to the social time allocation data of 8 children with autism spectrum disorder. The equation was effective in quantifying sociability, accounted for a large proportion of variance in participants' behavior, did so equally well for participants who were social and avoidant, and provided a more sensitive measure relative to those used in previous research. The implications of this methodology, its potential utility, and directions for future research are discussed.

Stimulus control depends on the subjective value of the outcome

Stimuli that provide information about likely future reinforcers tend to shift behavior, provided a reliable relation between the stimulus and the reinforcer can be discriminated. Stimuli that are apparently more reliable exert greater control over behavior. We asked how the subjective value (measured in terms of preference) of reinforcers associated with stimuli influences stimulus control. Five pigeons worked on a concurrent chains procedure in which half of all trials ended in a smaller reinforcer sooner, and the other half in a larger reinforcer later. In Signaled trials, the color and flash duration on the keys in the initial link signaled the outcome of the trial. In Conflicting probe trials, the color and the flash duration signaled conflicting information about the outcome of the trial. Choice in Signaled trials shifted toward the signaled outcome, but was never exclusive. In Conflicting probe trials, control was divided idiosyncratically between the 2 stimulus dimensions, but still favored the outcome with the higher subjective value. Thus, stimulus control depends not only on the perceived reliability of stimuli, but also on the subjective value of the outcome.

Behavioral momentum and accumulation of mass in multiple schedules

Behavioral momentum theory suggests that the relation between a discriminative-stimulus situation and reinforcers obtained in that context (i.e., the Pavlovian stimulus-reinforcer relation) governs persistence of operant behavior. Within the theory, a mass-like aspect of behavior has been shown to be a power function of predisruption reinforcement rates. Previous investigations of resistance to change in multiple schedules, however, have been restricted to examining response persistence following protracted periods of stability in reinforcer rates within a discriminative situation. Thus, it is unclear how long a stimulus-reinforcer relation must be in effect prior to disruption in order to affect resistance to change. The present experiment examined resistance to change of pigeon's key pecking following baseline conditions where reinforcer rates that were correlated with discriminative-stimulus situations changed. Across conditions, one multiple-schedule component arranged either relatively higher rates or lower rates of variable-interval food delivery, while the other component arranged the opposite rate. These schedules alternated between multiple-schedule components across blocks of sessions such that reinforcer rates in the components were held constant for 20, 5, 3, 2, or 1 session(s) between alternations. Resistance to extinction was higher in the component that most recently was associated with higher rates of food delivery in all conditions except when schedules alternated daily or every other day. These data suggest that resistance to change in multiple schedules is related to recently experienced reinforcer rates but only when multiple-schedule components are associated with specific reinforcer rates for several sessions.