Fading and errorless transfer in successive discriminations

Area of Science:

• Behavioral Psychology
• Animal Cognition
• Stimulus Control

Background:

• Established a successive discrimination task using red (positive) and green (negative) stimuli in pigeons.
• Introduced compound stimuli by superimposing lines of varying angular orientations onto the colored stimuli.

Purpose of the Study:

• To investigate how line elements acquire stimulus control when presented with color stimuli.
• To examine the role of stimulus attenuation in the development of stimulus control by compound stimuli.
• To understand how errorless performance is maintained during changes in stimulus predictability.

Main Methods:

• Gradually attenuated either the positive color, the negative color, or both, while presenting line elements alone as probes.
• Assessed the degree of control exerted by line elements before each attenuation phase.
• Analyzed the number of stimulus dimensions controlling responding based on attenuation conditions.

Main Results:

• Angular orientation of lines acquired stimulus control in an errorless manner when the positive color was attenuated (alone or with the negative color).
• Line elements did not acquire control when only the negative color component was attenuated.
• Attenuation of the negative stimulus affected the number of stimulus dimensions controlling responding; one dimension controlled when both colors were attenuated, but multiple dimensions controlled when only the positive color was attenuated.

Conclusions:

• Changes in the predictability of reinforcement by color and line elements during stimulus attenuation explain the observed results.
• Errorless performance can be maintained while organisms attend to different dimensions of novel stimuli.
• The specific attenuation condition influences the dimensionality of newly acquired stimulus control.