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

Abstract

Ten 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 postreinforcement 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.

Control by reinforcers across time and space: A review of recent choice research

“…Even in single and mixed schedules in which the time between consecutive reinforcers varies, the relation between one reinforcer and the next exerts some control over postreinforcer pause duration. Pauses increase with the minimum interreinforcer interval (e.g., Church & Lacourse, ; Schneider, ; Todorov, de Carvalho, Couto, da Cruz, & da Cunha, ), and when the time between reinforcers increases or decreases systematically with the number of reinforcers obtained, so too does the duration of the pause (Church & Lacourse, ). Finally, Williams () reported that performance in one component of a multiple schedule is affected by the contingencies in the following component, and Nevin () showed that resistance to change in a multiple‐schedule component was positively related to the following component reinforcer rate.…”

Temporal control in chained fixed-ratio, fixed-interval schedules.

“…The present and previous results (Todorov & Teixeira-Sobrinho, 2009;Todorov et al, 2012) indicate that temporal control in FI or FR schedules may be influenced by contextual variables. At least four variables might influence the temporal control over FI pauses in chained FR FI schedules, including the size of the FR requirement, the discriminative stimulus, FI length, and IRI.…”

“…Data from 11 rats (five rats from Todorov & Teixeira-Sobrinho, 2009; four rats from Todorov et al, 2012; two rats from the present study) and two rats in Figure 1 show that pauses in FI schedules in the chained FR 5 FI 60 s schedule are shorter than in simple FI schedules. An important consideration is the different experimental manipulations in these studies.…”

“…Pauses before the FR systematically increased as the FI duration increased. Figure 2 also shows preratio pauses in a chained FR 5 FI 60 s schedule from Todorov & Teixeira-Sobrinho (2009) and Todorov et al (2012). Pauses in the FR schedule in these two previous studies increased with slight increases in the FR schedule.…”

“…If the time to the next reinforcement is the controlling variable in FI schedules, then FI pauses should remain constant with changes in the FR schedule. However, previous studies showed that pauses in the second component decrease with increases in the FR requirement (de Souza & Todorov, 1975;Todorov & Teixeira-Sobrinho, 2009;Todorov, Carvalho, Couto, da Cruz, & Cunha, 2012). Temporal control in chained schedules appears to be a function of the IRI and not a function of the fixed time to the next opportunity for reinforcement signaled by a discriminative stimulus.…”