Time horizons in rats foraging for food in temporally separated patches.

Timberlake, William; Gawley, Donald J.; Lucas, Gary A.

doi:10.1037/0097-7403.13.3.302

Cited by 77 publications

(74 citation statements)

References 36 publications

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“…If contrast occurred when time-outs were 16 min long, but not when they were 32 min long, then the results would be consistent with Timberlake's findings (e.g., Lucas et al, 1988;Timberlake et al, 1987). This would show that the time course for integrating rewards hassome generality across species (pigeons as weil as rats), procedures (behavioral contrast as well as anticipatory contrast or foraging), and the absence of rewards as weIl as their presence.…”

Section: Discussionsupporting

confidence: 78%

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Positive behavioral contrast as a function of time-out duration when pigeons peck keys on a within-session procedure

McSweeney

Melville

1991

Animal Learning & Behavior

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Three pigeons pecked keys for food reinforcersdelivered by multiple variable interval variable interval schedules in the first part of each session (baseline) and by multiple variable interval extinction schedules in the second part of each session (contrast). The variable interval schedules delivered reinforcers after an average of 4 min or 30 sec in different conditions. The duration of a time-out between the components varied in five steps from 5 10 120 sec. Positive contrast occurred for all time-out durations in both experiments. That is, the rate of responding emitted during the constant, variable interval component was greater during the contrast than during the baseline schedules. The size of contrast did not change systematically with changes in timeout duration. These results violate most theories of contrast. They are compatible with the idea that animals integrate reinforcers over intervals longer than 2 min.Positive behavioral contrast is an increase in the rate of responding emitted during a constant component of a multiple schedule with a worsening of the conditions of reinforcement in the other component. Positive contrast is usually studied by comparing responding during a baseline schedule, in which both components provide the same conditions of reinforcement, with responding during a contrast schedule, in which one component is held constant (the constant component) and the other component is changed to extinction (the changing component).Most theories of contrast predict that contrast will decrease in size if a time-out is interposed between the components of the multiple schedule. During a time-out, the stimuli that signal the components are omitted and no reinforcers are delivered. The theories differ in exactly how they make that prediction.Rachlin (1973) During the baseline schedule, operantly conditioned responses occur during both components because responses produce reinforcers. No classically conditioned responses occur because the two components provide identical rates of reinforcement. During the contrast schedule, operantly conditioned responses occur during the constant component because responses still produce reinforcers. Classically conditioned responses also occur because the appearance of the constant component represents a transition from astimulus that signals a lower valued reinforcer (extinction in the changing component) to astimulus that signals a higher valued reinforcer (a schedule of reinforcement in the constant component). If classically conditioned responses facilitate operantly conditioned responses, then response rates will be higher during the constant component ofthe contrast schedule (operantly plus classically conditioned responses) than during the constant component of the baseline schedule (operantly conditioned responses only) and positive contrast will be observed.Interposing a time-out between components should eliminate contrast because it eliminates transitions between stimuli of different values. Eliminating value transitions removes classically con...

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Section: Discussionsupporting

confidence: 78%

“…Timberlake has also shown that animals may integrate rewards over intervals as long as 16 min (e.g., Lucas, Gawley, & Timberlake, 1988;Timberlake, Gawley, & Lucas, 1987). In a procedure sirnilar to that used to study behavioral contrast, Lucas et al (1988) measured the consumption of a 0.15 % saccharin solution followed by a 32 % sucrose solution.…”

mentioning

confidence: 99%

Positive behavioral contrast as a function of time-out duration when pigeons peck keys on a within-session procedure

McSweeney

Melville

1991

Animal Learning & Behavior

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“…Timberlake (1984) found that responding at high ratios in progressiveratio schedules was not reduced by free food given an hour after the session. Timberlake, Gawley, and Lucas (1987) extended these results, showing that only when free food was available within 15 min of the end of the session was responding affected. The findings of Timberlake and associates rule out any important substitution effect due to supplemental feeding.…”

mentioning

confidence: 48%

Does satiation close the open economy?

Posadas-Sánchez

Killeen

2005

Learning & Behavior

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Pigeons responded on fixed-interval and fixed-ratio food schedules during sessions of extended duration. Pause lengths from the beginning of the session, when the subjects were hungry, resembled those found in open economies, whereas pause lengths from the end of the sessions, when the subjects were close to satiation, resembled those from closed economies. A model of motivation captured key features of the data, suggesting that a changing level of hunger is a causal factor in the behavioral differences observed between open and closed economies. Behavioral theories may provide a parsimonious alternative to economic theories in accounting for such effects.

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“…However, the psychological literature reveals that anticipation of future events based on earlier exposure is unlikely to alter current behavior unless future events occur within minutes. Rats, for instance, will work hard to obtain vanishing resources despite the fact that all their food could be obtained from a rich patch that materializes only 15 min later (Timberlake et al 1987). That is, they were unaffected by the availability of future foraging opportunities beyond a time horizon of 15 min.…”

Section: Cognitive Constraintsmentioning

confidence: 99%