Color Discrimination in Weanling Pigs

Abstract

Two experiments were carried out in order to determine whether color perception exists in weanling pigs. In Exp. I, two female weaners (one Landrace x Large white and one Large White) were trained using a T-maze technique to go behind a positive stimulus color card to receive feed as a reward. Three colors, red, green and blue which have the same luminosity, were compared in a pairwise fashion. Both weaners discriminated blue from green and blue form red, but both failed to discriminate red from green. In Exp. II, two female weaners (one 1/4 Landrace x 3/4 Large White and one Duroc x Large White) were trained using an operant conditioning technique to press a switch under a positive stimulus color card with their nose to receive feed as a reward. Each of the three colors used in Exp. I, was respectively paired with gray of the same luminosity. Both weaners discriminated blue from gray but failed to discriminate red from gray and green from gray. Results indicate that weaners are able to discriminate only blue among the three primary colors.