Local contrast in multiple schedules: the effect of stimulus discriminability

Area of Science:

• Behavioral psychology
• Animal behavior

Background:

• Contrast effects are crucial in understanding operant conditioning.
• The role of discriminative stimuli, like wavelength differences, in contrast effects requires further investigation.

Purpose of the Study:

• To investigate how wavelength differences between schedule components influence positive and negative local contrast in pigeons.
• To examine the relationship between differential responding and the dissipation of contrast effects.

Main Methods:

• A three-ply multiple schedule was employed with pigeons.
• Response rates during a standard component were measured based on the preceding schedule component.
• Experimental conditions manipulated the wavelength differences signaling the schedule components.

Main Results:

• Pigeons in a narrow wavelength range exhibited positive local contrast (higher rate after extinction).
• Pigeons in both narrow and medium wavelength ranges showed negative local contrast (lower rate after a richer component).
• Positive contrast dissipated with the establishment of differential responding; negative contrast was inversely related to wavelength differences.

Conclusions:

• Wavelength differences play a significant role in modulating both positive and negative contrast effects.
• Discrimination between schedule components is essential for understanding the mechanisms of contrast.
• Future theories of contrast must integrate the role of discrimination in both positive and negative contrast phenomena.