Memory for the Spatial Position of an Imprinting Object in Junglefowl Chicks

Abstract

Abstract The characteristics of memory for the position of an imprinting object were investigated in junglefowl chicks (Gallus gallus spadiceus). Subjects were exposed individually and continuously to an imprinting object located in one of the two back quadrants of their home cage ('training quadrant'). Positioning of chicks in a test cage was studied from 7 to 1 days after hatching. In experiment 1 chicks preferred the training quadrant over the other back quadrant when tested in an empty cage, but not when two identical training objects were present, one in each back quadrant. In tests with one training object present, chicks showed more shrill calling when the object was in a novel position than when it was in the training position, but only during the first minute of a 5-min test. The strength of position preferences was independent of the effectiveness of the training object as an imprinting stimulus. In experiment 2a, chicks switched the position preference in an empty cage from the training quadrant to the other back quadrant after 2 h of exposure to the training object in that back quadrant of the home cage. In experiment 2b however, chicks still preferred the original training shape to a novel shape, after 2 h of exposure to an object with that novel shape. These results show that position memory in filial behaviour is less stable than memory for the physical properties of the imprinting object, and that position responses occur when chicks are motivated to seek contact with the object.