Variable-time reinforcement in multiple and concurrent schedules.

Area of Science:

• Behavioral psychology
• Animal behavior
• Operant conditioning

Background:

• Behavioral contrast is a phenomenon where changes in response rates in one component of a multiple schedule are influenced by conditions in another component.
• Previous research has explored various factors contributing to behavioral contrast, including reinforcement density and schedule-induced behaviors.

Purpose of the Study:

• To investigate the role of reduced response rates in the occurrence of behavioral contrast.
• To test the preference interpretation of behavioral contrast by comparing extinction and variable-time schedules.

Main Methods:

• Experiment I: Four rats and a pigeon were exposed to a two-component multiple schedule. One component was a variable-interval schedule; the second was either a variable-time schedule or extinction, both reducing response rates.
• Experiment II: Two rats allocated time between concurrent schedules, one variable-interval and one variable-time, to assess preference.

Main Results:

• Behavioral contrast was observed only when extinction was the second component, despite both extinction and the variable-time schedule reducing responding.
• Rats in Experiment II showed no preference between the variable-interval and variable-time schedules.

Conclusions:

• The findings support the preference interpretation of behavioral contrast.
• Behavioral contrast appears to result from the introduction of a less-preferred condition within a multiple schedule, rather than solely from a reduction in response rate.