On the roles of the human frontal eye fields and parietal cortex in visual search

Successful search for a target in a visual scene requires many cognitive operations, including orienting, detecting the target, and rejecting distractors. Performance in search is affected by a number of factors, including the number of targets and distractors, their similarity, motion in the display, location, and viewing history of the stimuli, etc. A task with so many stimulus variables and behavioural or neural responses may require different brain areas to interact in ways that depend on specific task demands. Until recently the right posterior parietal cortex has been ascribed a pre-eminent role in visual search. Based on recent physiological and brain imaging evidence, and on a programme of magnetic stimulation studies designed to compare directly the contributions of the parietal cortex and the human frontal eye fields in search, we have generated an account of similarities and differences between these two brain regions. The comparison suggests that the frontal eye fields are important for some aspects of search previously attributed to the parietal cortex, and that accounts of the cortical contributions to search need to be reassessed in the light of these findings.