Symbolic Matching-to-Sample by Pigeons

Abstract

Pigeons were given 4 sessions, 90 reinforcers per session, in which the center one of three response keys was illuminated with red and green light. 40 responses on the center key produced side keys displaying white vertical and horizontal lines on black backgrounds. Red was “symbolically” matched by responding to the vertical lines and green by choice of the horizontal lines. A 25-sec. intertrial interval and a correction procedure for errors were in force. 90% or better matching occurred on the third session. A transfer task was derived by using figures as samples and colors as comparison stimuli. Reversal of the positions greatly disrupted performance. The animals learned to respond in the presence of each sample but did not appear to have learned the symbolic relations between colors and figures.