Processing from LVF, RVF and BILATERAL presentations: examinations of metacontrol and interhemispheric interaction.

Observers indicated whether two successively presented drawings of faces were identical or differed in one feature (hair, eyes, mouth, jaw). The first face of each pair was presented at the fixation point and the second was presented to the left visual field-right hemisphere (LVF-RH), right visual field-left hemisphere (RVF-LH), or to both visual fields simultaneously (BILATERAL). On DIFFERENT trials the RT of correct responses depended on which feature differed and the pattern of feature location effects was significantly different on LVF-RH and RVF-LH trials. On BILATERAL trials the feature location effect was identical to that obtained on RVF-LH trials and significantly different from that obtained on LVF-RH trials. In addition, the percentage of errors and RT of correct responses were both higher on BILATERAL trials than on unilateral trials. Implications of these results are considered for the concept of "metacontrol" in neurologically normal humans and for models of interhemispheric interaction.