[The function of visual imagery and effect of input modality in spatial transformation task by blind and sighted adults (author's transl)].

The function of visual imagery and the effect of input modality in spatial transformation task was examined in 24 blind and 18 sighted students. Early blind, late blind and blind-folded sighted persons were presented with the information about four objects which were placed randomly on a board. They identified those objects haptically (with touch and movement) or verbally. After a practice session with one object, the subjects were told to locate the position of the other three objects (simple reconstruction trials) and then, to imagine that he/she had moved to a position behind the other object and to make similar evaluation of the imagined position (perspective transformation trials). These groups were well matched in simple reconstruction. But on perspective transformation trials, a highly significant interaction between sight status and input modality was found. Input modality affected the blinds only. Their error rate was significantly higher than the sighted persons in verbal input condition. In haptically input condition, the blind did not differ from the sighted. These results suggest visual imagery plays a major role when there are few or no perceptual cues in which to evaluate a situation.