Predisposed visual memory of shapes in quail chicks

Newly hatched chicks will spontaneously peck at conspicuous objects in thei r field of view, and soon learn to distinguish between edible food particle s and unpleasant tasting objects. To examine whether the selective pecking is based on the ability to memorize shapes, we analyzed pecking behavior of 1- to 2-days-old quail chicks (Coturnix japonica) by using ball- and trian gle-shaped beads both painted in green. Repeated presentation of dry bead ( either ball or triangle) resulted in a progressively fewer number of pecks (habituation). When chicks were tested by triangle after repeated presentat ion of ball, chicks showed a significant increase in the number of pecks at the triangle (dishabituation). On the other hand, when tested by ball afte r a series of triangle presentations, pecking frequency did not increase (n b dishabituation). Chicks thus distinguished the triangle as a novel object after being habituated to ball, but did not respond to the ball after tria ngle. A similar asymmetry was found in one-trial passive avoidance task. Ch icks were pre-trained by water-coated (neutral) triangle and then trained b y methylanthranilate-coated (aversive) ball. In this case, most chicks lear ned to avoid the ball, and half of these successful learners pecked at the triangle; they distinguished triangle from ball. When chicks were pre-train ed by neutral ball and trained by aversive triangle, on the other hand, mos t chicks did not distinguish the ball from triangle, and showed a generaliz ed avoidance for both beads. Chicks may be innately predisposed to memorize a limited category of shapes such as ball, and associate them with selecti ve avoidance.