Abstract:We investigated the duration of lever pressing by rats when the delivery of appetitive reinforcers was contingent upon response duration. In the first experiment, response durations increased when duration requirements were imposed, and they decreased when duration requirements were removed. This effect occurred whether reinforcers were immediate or delayed by 8 s. In order to maintain the integrity of the delay intervals, reinforcer delivery was dependent upon both lever depression and release. In a second ex… Show more
“…A secondary goal of this study was to characterize the distribution of response durations emitted under a VI schedule. Whereas the motoric hypothesis of δ assumes that the time to emit a response is fixed, direct measurements of lever-press durations have found them to vary between responses (Byrne & Sarno, 2019;Fowler, Filewich, & Leberer, 1977;Roberts & Gharib, 2006; see Fig. 1c).…”
Operant behavior is organized in bouts that are particularly visible under variable-interval (VI) schedules of reinforcement. Previous research showed that increasing the work required to produce a response decreases the rate at which bouts are emitted and increases the minimum interresponse time (IRT). In the current study, the minimum effective IRT was directly manipulated by changing the minimum duration of effective lever presses reinforced on a VI 40-s schedule. Contrary to assumptions of previous models, response durations were variable. Response durations were typically 0.5 s greater than the minimum duration threshold; durations that exceeded this threshold were approximately log-normally distributed. As the required duration threshold increased, rats emitted fewer but longer bouts. This effect may reflect an effort-induced reduction in motivation and a durationinduced facilitation of a response-outcome association.
“…A secondary goal of this study was to characterize the distribution of response durations emitted under a VI schedule. Whereas the motoric hypothesis of δ assumes that the time to emit a response is fixed, direct measurements of lever-press durations have found them to vary between responses (Byrne & Sarno, 2019;Fowler, Filewich, & Leberer, 1977;Roberts & Gharib, 2006; see Fig. 1c).…”
Operant behavior is organized in bouts that are particularly visible under variable-interval (VI) schedules of reinforcement. Previous research showed that increasing the work required to produce a response decreases the rate at which bouts are emitted and increases the minimum interresponse time (IRT). In the current study, the minimum effective IRT was directly manipulated by changing the minimum duration of effective lever presses reinforced on a VI 40-s schedule. Contrary to assumptions of previous models, response durations were variable. Response durations were typically 0.5 s greater than the minimum duration threshold; durations that exceeded this threshold were approximately log-normally distributed. As the required duration threshold increased, rats emitted fewer but longer bouts. This effect may reflect an effort-induced reduction in motivation and a durationinduced facilitation of a response-outcome association.
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