1975 Volume 17 Issue 3 Pages 133-140
Six groups of 6 pigeons were monocularly trained with a line stimulus equivalent to radius of a pecking key (a single stimulus training group, a interdimensional discrimination group, a oblique-vertical discrimination group, a lateral mirror image discrimination group, a vertical mirror image discrimination group and a lateral-vertical mirror image discrimination group). After 3 types of the mirror image discrimination trainings and the oblique-vertical discrimination training generalization gradients with the untrained eye exhibited a peak at the lateral mirror image of SD. Whereas, after the interdimensional discrimination training and the single stimulus training generalization gradients with the untrained eye showed a bimodal pattern with peaks at SD and its lateral mirror image.