Global form perception in cats early deprived of pattern vision.

Recently, we showed that binocularly deprived cats are not able to detect global motion in a random dot pattern (Burnat et al., 2002). Here, we examined, in these animals, a global form discrimination task, that is, distinction of a square from a rectangle, matched for total surface. In contrast to the previously tested motion task, binocularly-deprived cats, as compared with controls, performed only at higher thresholds. Interestingly, the increase of the stimuli's surface, or a shift from horizontal to vertical orientation of the rectangle, significantly impaired their performance. We therefore conclude that binocularly-deprived cats do not attend to the global form of the stimuli. Instead, they spontaneously choose a local cue to discriminate and are not able to modify it.