Semester

Fall

Date of Graduation

2004

Document Type

Thesis

Degree Type

MA

College

Eberly College of Arts and Sciences

Department

Psychology

Committee Chair

Michael Perone.

Committee Co-Chair

Kennon A. Lattal

Committee Member

Barry Edelstein

Abstract

Twelve rats were exposed to two variable-time schedules that differed in their rates of food delivery. The "imposed" schedule was normally in effect, but lever pressing occasionally switched to the "alternate" schedule for periods averaging 30 s. Increases in food frequency afforded by switching to the alternate schedule were manipulated across conditions. All rats were exposed to the same absolute food frequency increases, but the programming of these increases was varied among the rats by holding particular food delivery rates constant across conditions. For half of the rats, the schedules were signaled. In general, response rates were directly related to the size of the food-frequency increase, although the effect was more robust when the schedules were signaled. Response rates were undifferentiated when imposed schedule food delivery rates were held constant. The results lend limited support to the molar account that behavior is sensitive to changes in rates of stimulus events.

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