Encoding Direction in Manipulatory Space and the Role of Visual Experience

Abstract

Congenitally blind, adventitiously blind, and blindfolded sighted adults made direction estimates of target position within manipulatory space after their index fingers were guided to each target from a neutral starting point. Observers remained seated in the same location throughout the experiment. In a “finger-movement” condition, observers’ fingers were guided to a target location from which they pointed to each of the other targets. In an “imagination” condition, the observers pretended they were at one of the target locations and pointed to the other targets as if they occupied the new target position. Regardless of visual experience, observers in the finger-movement task were more accurate, but only negligibly faster, than in the imagination task. The subjective reports of all groups suggested that cognitive-mapping heuristics were used in both tasks, contrasting with previous results obtained in ambulatory space (Rieser, Guth, & Hill, 1982). The results are considered in the light of a fundamental difference between manipulatory and ambulatory space.