First trial rewards promote 1-trial learning and prolonged memory in pigeon and baboon.

There is a long-standing debate in educational settings on the influence of positive and negative consequences on learning. Although positive rewards seem desirable from an ethical perspective, 1-trial learning has been best demonstrated in the animal literature with tasks using highly salient negative consequences, such as shock or illness, and so far only in tasks requiring the acquisition of a singular stimulus-response association. Here we show that pigeons and baboons can concurrently learn, in a cognitively challenging memorization task, hundreds of picture-response associations after a single exposure and that this rapid learning is better promoted by a positive outcome after the first picture presentation. Further, the early positive outcomes had beneficial effects on the memory of learned acquisitions that was detectable up to 6-8 months after initial training. Beyond their significance for educational policies, these findings suggest that the psychological and brain mechanisms controlling rapid, often 1-trial, learning have a long evolutionary history. They may represent the phylogenetic precursor for the disproportionate impact of first impressions in humans and the phenomenon of fast word learning in children.