Human Frontal Eye Fields and Visual Search

1 Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD; and 2 Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom Submitted 3 December 2002; accepted in final form 15 February 2003 Recent physiological recording studies in monkeys have suggested that the frontal eye fields (FEFs) are involved in visual scene analysis even when eye movement commands are not required. We examined this proposed function of the human frontal eye fields during performance of visual search tasks in which difficulty was matched and eye movements were neither necessary nor required. Magnetic stimulation over FEF modulated performance on a conjunction search task and a simple feature search task in which the target was unpredictable from trial to trial, primarily by increasing false alarm responses. Simple feature search with a predictable target was not affected. The results establish that human FEFs are critical to visual selection, regardless of the need to generate a saccade command. Address for reprint requests: N. Muggleton, Dept. of Experimental Psychology, Univ. of Oxford, South Parks Rd., Oxford OX1 3UD, UK (E-mail: neil.muggleton{at}psy.ox.ac.uk ).