Tactile sensibility in parietal lesions.

The response to tactile stimuli at the threshold range was studied with a forced choice technique in two patients with stable parietal lesions. The most unexpected finding was that very weak stimuli were significantly better detected on the side contralateral to the lesion. The psychometric functions were also less steep and reached a ceiling at below 100% correct responses. The findings are interpreted as due to the combined effect of decreased sensitivity to alterations in stimulus strength and decreased local attention.