EARLY VISUAL EXPERIENCE AFFECTS MEMORIZATION AND SPATIAL REPRESENTATION OF PROPRIOCEPTIVE TARGETS

FIVE subjects who had been blind from an early age and five age-matche d blindfolded sighted subjects were engaged in a spatial memory task. Locations to be memorized were presented on a sagittal plane by passiv e positioning of the left index finger. A go signal for matching the t arget location with the right index finger was provided 0 or 8s after left hand positioning. Constant errors in amplitude and direction of m ovement and pointing distribution observed after the longer delay diff ered across groups. Pointing variability was higher in the blindfolded sighted group. In addition, the main axis of pointing distributions o btained in the blindfolded sighted group were aligned with the target array for the 8s but not the 0s delay.(1) By contrast, the main axis t ended to be aligned with movement direction for blind subjects for bot h delays. These results suggest that memorizing a proprioceptively def ined target may involve distinct spatial representations according to delay and to early visual experience.