Do our brain hemispheres exchange some stimulus aspects better than others?

The communication between the two brain hemispheres involves considerable information losses. This study investigated whether these losses might be reduced for frequently processed stimulus attributes and currently attended stimulus properties. It was assumed that size should be more often processed than animateness, since estimating object size is essential for motor planning. Thus, if the transfer deficits were curbed for frequently processed stimulus aspects, then they should be smaller for size than for animateness. By contrast, if the transfer losses were reduced for currently attended stimulus features, then they should depend on the task: in a size judgement task they should be smaller for size, and in an animateness judgement task they should be smaller for animateness. To test the interhemispheric transmission of the two stimulus properties, a lateralized priming paradigm was implemented, in which one group of participants judged targets according to their size and another group according to their animateness. It was found that the transfer deficits were virtually absent for size, but very pronounced for animateness. Hence, the present data provide the first evidence that interhemispheric transmission losses vary for particular stimulus features and that they may be reduced with practice. Since there was no priming for unattended stimulus properties, it remains open whether attention to certain stimulus aspects can improve the interhemispheric exchange as well.