Effect of Schedule-Induced Behavior on Responses of Spontaneously Hypertensive and Wistar–Kyoto Rats in a Delay-Discounting Task: A Preliminary Report

Abstract

Delay discounting is the loss of the subjective value of an outcome as the time to its delivery increases. It has been suggested that organisms can become more tolerant of this delay when engaging in schedule-induced behaviors. Schedule-induced behaviors are those that develop at a high rate during intermittent reinforcement schedules without the need of arranged contingency to the reinforcer, and they have been considered as a model of compulsivity. There is evidence that relates compulsivity to greater delay discounting. The rate of delay discounting represents how impulsive the subject is, as the rate of discounting increases the higher the impulsivity. Thus, the main purpose of this study was to undertake a preliminary evaluation of whether developing schedule-induced behaviors affects performance in a delay-discounting task, by comparing spontaneously hypertensive rats (SHRs) and Wistar–Kyoto (WKY) rats. The rats were exposed to a task that consisted of presenting the subjects with two levers: one produced a small, immediate food reinforcer while the other one produced a larger, delayed reinforcer. During Condition A, the levers were presented, and a water bottle and a running wheel were available in the conditioning chambers; during Condition B, only the levers were presented. SHR and WKY rats developed schedule-induced behaviors during Condition A and showed no difference in discounting rates, contradicting previous reports. Lick allocation during response-reinforcer delays and the inter-trial interval (ITI) showed, respectively, pre- and post-food distributions. Discounting rates during Condition B (when rats could not engage in schedule-induced behaviors) did not reach statistical significance difference among strains of animals, although it was observed a tendency for WKY to behave more self-controlled. Likewise it was not found any effect of schedule-induced behavior on discounting rates, however, a tendency for WKY rats to behave more impulsive during access to drink and run seems to tentatively support the idea of schedule-induced behavior as a model of compulsivity in those rats, being impulsivity simply defined as an excess in behavior.

Using rodent data to elucidate dopaminergic mechanisms of ADHD: Implications for human personality

“…Some researchers have reported steeper discounting rates in the SHRs (Aparicio et al, 2019;Bizot et al, 2007;Carbajal et al, 2023;Fox et al, 2008;Orduna, 2015). Others have reported no difference between SHR and comparison strains (Adriani et al, 2003;Garcia & Kirkpatrick, 2013;Gonzalez-Barriga & Orduna, 2022;Ramos, Lopez-Tolsa, Sjoberg, & Pellon, 2019).…”

Psychological flexibility: An attempt to remove theoretical elements from the estimation

“…This study analyzes schedule-induced behavior in self-control situations, given that ideas about delay discounting are incorporated into the model. The tasks assumed are general self-control tasks, as presented in Ramos et al (2019). Self-control tasks (e.g., Rachlin and Green (1972)) require a choice between two alternatives: a small reinforcer presented immediately (smaller and sooner; SS) and a larger reinforcer presented after a delay (larger PSYCHOLOGICAL FLEXIBILITY 10 and later; LL).…”

“…The amount of response of schedule-induced behavior is generally plotted in an inverted U-shape against the measured elapsed time Ramos et al (2019).…”

“…Two types of artificial data for model validation are provided in Table 1, following Ramos et al (2019) and P. Killeen (1975). Then, using the parameter values described above, 16,000 simulations were performed for each sample.…”

Assessment of the ‘timing’ function of schedule-induced behavior on fixed-interval performance.

“…After several years of investigating schedule-induced behaviors, Pellón and colleagues (Ardoy & Pellón, 2004; Gutiérrez-Ferre & Pellón, 2019; Íbias & Pellón, 2011; Pellón & Blackman, 1987; Pellón & Castilla, 2000; Pellón & Pérez-Padilla, 2013; Ramos et al, 2019) concluded that they are operants, either individually maintained by delayed reinforcement (Killeen & Pellón, 2013; Pellón & Killeen, 2015) or as part of a behavioral pattern that is reinforced as a whole and is repeated on every interreinforcement interval (Ruiz et al, 2016; Segal et al, 1965), a view that is also consistent with Skinner’s proposal on contiguity, instead of contingency, as necessary for the establishment of an operant behavior (Skinner, 1948).…”