[Simultaneous differentiation of visual stimuli in chickens]

Differentiation of colour stimuli and geometrical figures was studied in chickens by the food-procuring reflex method with simultaneous presentation of the stimuli. The percentage of correct selections of the positive conditioned stimulus was chosen as a measure of the degree of differentiation. Stable differentiation of colour stimuli appeared after 15.44 +/- 0.6 presentations of the conditioned stimuli reaching 97.66 +/- 0.69% of correct responses. Incomplete differentiation of geometrical figures appeared after 39.07 +/- 3.6 presentations, attaining 67.69 +/- 2.64%. Differentiation of geometrical figures became stable after training, its level rising up to 80.37 +/- 3.89%.