Haptic identification of rotated letters using the left or right hand.

The present study investigated the effects of the use of the left and right hands on haptic identification of letters which were presented in either a normal (0 degrees rotation), downward (90 degrees clockwise rotation), upside down (180 degrees rotation), or facing upward (270 degrees rotation) position. Each of the 80 right-handed subjects was given five series of randomly ordered presentations of sets of 8 letters of the alphabet. The subjects were asked to feel and then name each letter correctly as quickly but as accurately as possible. Times showed no effect of hand, but significant effects were found for different sets of letters, degree of rotation and a significant decrease in identification time was observed across the five series. Interactions occurred between hand and rotation as well as set and rotation. Errors showed a significant interaction of hand with degree of rotation; the right was superior at 0 degrees but the left was superior at 90 degrees. The results were discussed in terms of hypotheses of hemisphere function, mental rotation, and stimulus familiarity.