MEMORY-BASED SAME-DIFFERENT CONCEPTUALIZATION BY PIGEONS

We first trained pigeons to peck one button (same) after the successiv e presentation of 16 identical pictures and to peck a second button (d ifferent) after the successive presentation of 16 nonidentical picture s. Later, we tested the birds with other lists of same and different i tems composed of completely novel pictures. Accuracy to the testing li sts reliably exceeded chance levels, thus demonstrating same-different conceptualization by pigeons under conditions that, for the first tim e, (1) eliminated purely perceptual mechanisms of discrimination learn ing and transfer and (2) required memory-based processing of the exper imental stimuli.