Dissociated awareness of manual performance on two different visual associative tasks: a "split-brain" phenomenon in...

Subjects performed two visual category matching tasks. One task, shown in previous work to exhibit a left hemisphere superiority, was to decide if two different pictures represented the same object. In this task, verbal corrections of manual responses were usually correct (93%), indicating good verbal awareness of the task. The other task, previously shown to exhibit a right hemisphere superiority, was to decide if two different pictures represented the same emotional facial expression. Here, verbal corrections were random (58%), indicating poor verbal awareness of the task. The apparent dissociation of verbal and manual responses for the emotional expression matching task resembles results obtained with "split brain" patients.