Interhemispheric integration of information in a surface estimation task

Normal subjects were asked to estimate the total surface of two black spots presented tachistoscopically, either both to the right or both to the left visual field, or bilaterally to either visual field. Performance was highest with unilateral left visual field presentation and lowest with bilateral presentation of the spots. Interhemispheric integration varied with the quantitative relation between the stimuli in the left and right visual fields. Errors may be due in part to an insufficient cooperation of the left hemisphere and/or to an ignorance of the right hemisphere and/or to an unreliable transfer by the cerebral commissures.