Saccadic eye movements to seen and unseen targets: oculomotor errors in normal subjects resembling those of schizophrenics.

Schizophrenic subjects have defects in oculomotor control which appear to be the result of inefficient processing of sensory information, not a problem in controlling the movement itself [Mather and Putchat (1983b) J. Psychiat Res. 17, 343-360]. A demonstration that manipulating sensory information by removing context information alters these same saccadic eye movements in normals is the subject of the present research. Without context information (in the dark) people make more double-jump saccades and overshoot a target, as schizophrenics do usually. Normals have a reduced number of double saccades, a different pattern of eye movement, when the target itself is not visible. These findings reinforce the suggestions that schizophrenics, despite their normal oculomotor reaction time, are less effective than normal subjects at processing the spatial information which guides their eye movement.