Delay or Rate of Food Delivery as a Determiner of Response Rate

Abstract

PIGEONS WERE CONFRONTED WITH TWO KEYS: a green food key and a white changeover key. Food became available for a peck to the green key after variable intervals of time (mean = 113 seconds). A single peck on the changeover key changed the color of the food key to red for a fixed period of time during which the timing of the variable-interval schedule in green was suspended and the switching option eliminated and after which the conditions associated with green were reinstated. In Experiment 1 a single food presentation was obtainable during each red-key period after a minimum delay timed from the switch. This delay and the duration of the red-key period were held constant during a condition but varied between conditions (delay = 2.5, 7.5, 15, or 30 seconds; red-period duration = 30, 60, 120, 240, or 480 seconds). In Experiment 2 additional food presentations were scheduled during a 240-second red-key period with the delay to the first food delivery held constant at 30 seconds, and the delays to later food deliveries varied over conditions. Considering the data from both experiments, the rate of switching to red was a decreasing function of the delay to the first food, the delay to the second food, and perhaps the delay to the third food after a switch. There was no clear evidence that the rate of food in the red-key period made an independent contribution. The ordering of response rates among conditions was consistent with the view that each food presentation after a response adds an incremental effect to the rate of the response and that each food presentation's contribution is a decreasing function of its delay timed from the response.

Sensitivity of pigeons to prereinforcer and postreinforcer delay

“…For example, several researchers have shown strong control over pigeons' behavior by variations in prereinforcer delay but not by variations in more molar variables such as rate of reinforcer access (see Dunn & Fantino, 1982;Lea, 1979;McDiarmid & Rilling, 1965;Moore, 1979Moore, , 1982Shull, Spear, & Bryson, 1981). Hall-Johnson and Poling (1984) have recently shown that pigeons prefer a particular alternative with a shorter initial component, even if choice of that alternative yields less total food received over a session or if that alternative requires more responses to yield the same total access to food as another alternative.…”

Conditioned Reinforcement: Experimental and Theoretical Issues

“…The harmonic mean corresponds to the average immediacy of reinforcement associated with the stimulus, which must be distinguished from the average rate of reinforcement. Why immediacy should be more fundamental than rate is not obvious, but its dominance has been confirmed by several different procedures (e.g., Mazur, 1986;Shull, Mellon, & Sharp, 1990;Shull, Spear, & Bryson, 1981).…”

“…Also as noted above, the critical variable appears to be the immediacy of reinforcement predicted by the stimulus onset, rather than rate per se. An example ofthe differences between immediacy and rate is provided by Shull et al (1981), who presented pigeons with a choice between a constant VI schedule during a green key color and a different schedule correlated with a red key color that could be produced by a response to a changeover key. Once the changeover occurred, they remained in the presence of the red color for a predetermined period of time (e.g., 3 min).…”

Choice and the Initial Delay to a Reinforcer

“…Ordinarily, one would have expected the pigeons to be indifferent, since the schedules in effect during the alternatives were identical, and each alternative yielded the same overall rate of reinforcement. Grace and Nevin (2000) initially pondered the role of multiple reinforcers in the constant-duration terminal link, because research has shown that subjects may well prefer a choice alternative associated with multiple reinforcers rather than a single reinforcer per terminal-link entry (e.g., Fantino & Herrnstein, 1968;Mazur, 1986;McDiarmid & rilling, 1965;Moore, 1979;Poniewaz, 1984;Shull, Mellon, & Sharp, 1990;Shull, Spear, & Bryson, 1981). in particular, Grace and Nevin discussed their findings from the view correspondence concerning this article may be addressed to Dr. J. Moore, Dept.…”