RELATIONS BETWEEN INDIVIDUAL-DIFFERENCES IN OCULOMOTOR RESTING STATESAND VISUAL INSPECTION PERFORMANCE

Individual differences in the oculomotor resting states (dark vergence and dark focus) have previously been linked to subjective and visual consequences of near visual work. The present experiment investigated whether these resting states are related also to performance on a near visual inspection task. Dark vergence and dark focus were measured in 38 students before and after they spent 40 min searching for a target letter among distracter letters on a video display terminal at a dist ance of 20 cm. Subjects with relatively near dark vergence positions p erformed the inspection task significantly more quickly than subjects with relatively far dark vergence positions. Also, subjects who showed a relatively large inward shift in dark vergence tended to perform qu ickly. Inspection performance was not related to individual difference s in dark focus. These results extend existing oculomotor theory and s uggest that the performance of visual inspectors is maximized when the mismatch between the task distance and their dark vergence posture is minimized.