Ability of cattle to distinguish among different wavelengths of light

Eight heifers were trained using operant conditioning to press a plate to receive feed as a reward. Different wavelengths of light were the correct and incorrect stimuli. Positive and negative responses to the stimuli were registered electronically. Daily sessions of 20 min were conducted in a chamber from which external light had been excluded. A 75% correct choice was the criterion for acceptable discrimination. Ratios of correct to incorrect responses were computed. Three colors, i.e., green (535 nm), red (610 nm), and blue (450 nm), were compared pairwise during eight trials. Trial 7 was a repeat trial of green versus red and trial 8 was a comparison of green versus green. Subjects gave random response to green versus green. Five subjects distinguished red from blue: 1, 2, 3, 4, and 5 at 76, 91, 78, 88 and 81% correct choice, respectively. Three subjects distinguished blue from green: 1, 2, and 5 at 89, 88, and 85% correct choice, respectively. Three subjects distinguished green from red in a repeat trial: 1, 5, and 7 at 90, 84, and 85% correct choice, respectively. Subjects failed to discriminate these colors in the first red versus green trial. Results indicate that heifers can learn to discriminate between colors.