Young kittens can learn complex visual pattern discriminations

Abstract
Kittens begin to display visually elicited responses shortly after eye opening. The pupillary reflex1, optokinetic response2,3, visual placing3–5 and avoidance of the deep side of the visual cliff3,5–7 all appear between the second and fifth weeks of life, and evidence of visual learning in homing behaviour has been described at the same early age8. However, an attempt to elicit pattern preferences in kittens of this age (usually considered the easiest way to demonstrate discriminatory behaviour in immature organisms9) was unsuccessful, evidently because such kittens show little spontaneous visual interest10,11. This is surprising in view of electrophysiological findings which emphasise the importance of the fourth to sixth weeks in the development of cortical feature-analysing mechanisms12–14; perhaps the stimulus-seeking methodology of Dodwell et al.10,11 is inappropriate for the visual modality at such an early age. Recently, visual acuity measurements have been reported for kittens as young as 30 d of age using a contour versus no-contour discrimination on a modified Lashley jumping stand15,16. With this technique we have now trained kittens of under 50 d of age to perform more complex pattern discriminations.