Bergert Susanne, Windmann Sabine, Güntürkün Onur
Institute of Experimental Psychology II, Building 23.03, Heinrich-Heine University, Universitaetsstrasse 1, 40225 Duesseldorf, Germany.
Neuropsychologia. 2006;44(8):1457-67. doi: 10.1016/j.neuropsychologia.2005.11.017. Epub 2005 Dec 27.
The coordination of sensorimotor tasks involving both visual half-fields requires exchange of information between the brain hemispheres. So far, this interhemispheric information transfer has never been investigated under conditions where the two hemispheres receive different visual inputs and each hemisphere performs on a different task. The present study asked whether such conditions affect the transfer of information between the hemispheres, and if so, at which processing stage. We addressed these issues by pairing a face comparison task with a visual discrimination task (I-task) designed to interfere with the interhemispheric information transfer required for face comparison. One version of the I-task (experiment 1) required discrimination of the faces of John Lennon and Yoko Ono; the other version (experiment 2) required discrimination between the names 'JOHN' and 'YOKO'. Thus, the two I-task versions overlapped at early visual processing stages where visual feature analysis is carried out, but differed at later processing stages where words or faces are represented as objects. We found that both I-task versions disrupted the interhemispheric information transfer for the face comparison task. This indicates that when both hemispheres are occupied by separate tasks, interhemispheric communication is less efficient. In addition, our results suggest that the hemispheres exchange sensory information already at a rather early visual processing stage. Hence, visual feature analysis in one hemisphere is probably informed about feature analysis in the other hemisphere and may also be modulated by it.
