Behavioral contrast without response-rate reduction.

Area of Science:

• Behavioral psychology
• Animal behavior

Background:

• Behavioral contrast is a phenomenon where the rate of responding under one schedule of reinforcement changes when another schedule is introduced.
• Typically, response rates increase when a component with reduced reinforcement (like extinction) is added to a multiple schedule.

Purpose of the Study:

• To investigate whether a reduction in response rate during the extinction component is necessary for behavioral contrast to occur.
• To examine the conditions under which behavioral contrast manifests in a successive discrimination task.

Main Methods:

• Two experiments using pigeons trained on multiple variable-interval extinction schedules were conducted.
• Experiment I involved training on a multiple schedule with variable-interval and response-independent reinforcement, followed by association with extinction.
• Experiment II involved extensive training on a single variable-interval schedule before introducing a second stimulus associated with extinction.

Main Results:

• Behavioral contrast was observed in all subjects across both experiments, irrespective of response rate reduction in the extinction component.
• In Experiment I, contrast occurred even when pigeons initially showed low responding to the non-reinforced stimulus.
• In Experiment II, contrast was evident even when subjects showed minimal or no responding to the extinction stimulus, and the effect was not diminished in errorless learners.

Conclusions:

• Response reduction in one component of a multiple schedule is not a prerequisite for observing behavioral contrast.
• Behavioral contrast can occur robustly even when the extinction component elicits minimal or no responding.