Fixed-interval pause duration in chained fixed-ratio, fixed-interval schedules.

Gleidson Gabriel Da Cruz,Claudia Octavia Ribeiro Da Cunha,Kalliu Carvalho Couto,Lucas Couto De Carvalho,João Claudio Todorov

doi:10.3922/j.psns.2012.1.12

Abstract

rats were submitted to chained fixed-ratio (FR), fixed-interval (FI) schedules of reinforcement. A FR schedule at one lever produced a discriminative stimulus associated with a FI 60-s schedule of primary reinforcement (water) at the second response lever. In Experiment 1, the FI schedule was kept constant while the FR requirement was changed from one to seven responses under five different experimental conditions for five rats. Increases in the FR requirement resulted in increases in post- reinforcement pauses but also decreases in pauses in the FI schedule. Using another five rats, Experiment 2 tested the hypothesis that short pauses in the FI schedule result from the use of the chained schedules procedure. Baseline was a FI 80-s schedule. In the second condition, chained FR 1 FI 80-s schedules were programmed. The third condition was a return to baseline. In baselines 1 and 2, the FI pause was compatible with the literature but decreased considerably when a chained schedule was used. The present results support the hypothesis that the time between primary reinforcement presentations dominates the control of FI pauses over control by the onset of a discriminative stimulus. Keywords: timing; chained schedules; fixed ratio; fixed interval; water; rats.

Highlights

A review published by Lejeune, Richelle, and Wearden (2006) calls our attention to the importance of the work with the fixed-interval (FI) schedules of Ferster and Skinner (1957) for the study of interval timing in animals (e.g., Staddon & Cerutti, 2003)
Pilot studies showed an unexpected result in which pauses in the second component of chained fixed-ratio (FR) FI schedules were shorter than typical pauses in single FI schedules (e.g., Sherman, 1959; Schneider, 1969)
As the response requirement increased in subsequent experimental conditions, the pauses systematically decreased with the exception of Rat 1

Summary

Introduction

A review published by Lejeune, Richelle, and Wearden (2006) calls our attention to the importance of the work with the fixed-interval (FI) schedules of Ferster and Skinner (1957) for the study of interval timing in animals (e.g., Staddon & Cerutti, 2003). In FI schedules, the possibility of a reinforcing stimulus that follows a response depends on the time since the last reinforcement or since the presentation of a discriminative stimulus (e.g., Ferster & Skinner, 1957; Catania, 1984). One of several possibilities of studying timing behavior in FI schedules when the time to the reinforcement is signaled by some event other than primary reinforcement is chained schedules with FI as the second component (Ferster & Skinner, 1957). Pilot studies (de Souza & Todorov, 1975; Todorov & TeixeiraSobrinho, 2009) showed an unexpected result in which pauses in the second component of chained fixed-ratio (FR) FI schedules were shorter than typical pauses in single FI schedules (e.g., Sherman, 1959; Schneider, 1969). Pausing appeared to be controlled by the interreinforcement interval (variable) and not by the fixed time to the opportunity for reinforcement signaled by a discriminative stimulus

Methods

Results

Conclusion