Egocentric localization of visual targets depends on encoding retinal image position, position of eye-in-head, and the positions of other body parts. It is well-known that the gain of saccades can be rapidly and plasticly altered as a result of neuro-muscular changes and simple optical manipulations. It is not known how altered gain affects localization. This question amounts to asking whether (and for what tasks) the perceptual system """"""""knows"""""""" about gain changes. The answer would bear on our functional models of visuo-motor coordination. For practical reasons, it would be helpful to know if saccadic plasticity disturbed accurate visuo-motor performance. We will test localization, before and after modifying saccadic gain, by: (a) pointing with unseen hand, and (b) positioning a visual target (as in Miller, 1980). We will modify saccadic gains using an eye-position contingent visual display (as in Miller, et al, 1981).
