Hemispheric differences in the judgment of number.

Two manual reaction-time experiments examined visual field differences for the judgment of number. All told, three tasks (recognition/enumeration, magnitude judgment and oddity judgment) were performed on three nonverbal indicators of number (dot clusters, bargraphs and dials) and two verbal indicators (word names of numbers and digits). The results indicated that field differences depended largely on display format, not on the task. Thus, dot clusters, bargraphs and dials all showed a left visual field superiority, while words showed a right visual field superiority. There was no evidence of lateralization for digits.