Recognition of matching tasks and stimulus novelty as a function of unilateral brain damage

A 96-trial tachistoscope recognition task was given to 15 left-hemisphere-damaged, 12 right-hemisphere-damaged, and 30 non-brain-damaged subjects. Procedure called for a first stimulus presented for 250 msec, a 1-sec. pause, and a second stimulus for 250 msec. The stimuli were 12 animal drawings used in repeated series according to a random schedule. Six animals were familiar and six were novel. For half of the trials, the two pictures were of different animals. Size and position of the animal picture were controlled. Both reaction time and accuracy were independently scored. Judgments of same and different appear to function as if they are governed by different processes. For the control group, measures of same and different judgments do not correlate highly despite high internal consistency of subtests. Recognition of same becomes impaired with brain damage, but more so if the damage is rightsided. Recognition of different judgments shows considerably less sensitivity to the effects of unilateral brain damage.