Pigeons were trained to match-to-sample with several new methodologies: a large number of
stimuli, computer-drawn color picture stimuli, responses monitored by a computer touch screen,
stimuli presented horizontally from the floor, and grain reinforcement delivered onto the picture
stimuli. Following acquisition, matching-to-sample concept learning was assessed by transfer to
novel stimuli on the first exposure to pairs of novel stimuli; One group (trial-unique), trained
with 152 different pictures presented once daily, showed excellent transfer (80% correct). Transfer
and baseline performances were equivalent, indicating that the matching-to-sample concept
had been learned. A second group (2-stimulus), trained with only two different pictures, showed
no evidence of transfer. These results are discussed in terms of the effect of numbers of exemplars
on previous failures to find concept learning in pigeons, and the implications of the positive
finding from this experiment on abstract concept learning and evolutionary cognitive development.