Comparative approaches to same/different abstract-concept learning.

Martinho and Kacelnik (2016) imprinted newly hatched ducklings (Anas platyrhynchos domestica) with a moving pair of either same or different objects, and following only one session, the ducklings accurately transferred the same/different relationship to novel object pairs that maintained the training relationship. This rapid learning and transfer of the concepts same and different far outstrips the more gradual learning of these basic concepts by animals in associative-learning tasks in which reinforcement is given for correct responses.