PERCEPTUAL DIFFERENTIATION DURING CATEGORIZATION LEARNING BY PIGEONS

In Experiment 1, pigeons were trained to categorize two sets of variab le stimuli (black and white checkerboard patterns), constructed by ran dom distortions of two prototype patterns. They were subsequently trai ned on new discriminations, between two new exemplars of their positiv e category, two new exemplars of their negative category, or two contr ol checkerboard patterns. The new exemplars of their familiar categori es were easier to discriminate than the wholly novel stimuli, although this difference was significant only for exemplars of their previousl y negative category. In Experiment 2, pigeons were initially trained o n a discrimination between two prototype checkerboards; they subsequen tly learned to discriminate between two distortions of their negative prototype more rapidly than between two control patterns.