Discrimination learning in the pigeon with two relevant cues, one hard and one easy.

Abstract

Pigeons were trained on a colour/shape discrimination. Colour was shown to be the operative cue. No learning of shape was demonstrated after 500 overtraining trials, whereas the shape cue alone was learned in fewer trials than this. Learning of the ‘hard’ shape cue was thus suppressed by the presence of the ‘easy’ colour cue. It was not eliminated, however, for the shape cue was learned after 1000 overtraining trials.