Mechanism of selective attention: fMRI study of face-word Stroop task performance.

Selective attention is the cognitive process of selecting and processing the task relevant information and ignoring the task irrelevant information. Though the neural substrates involved in this cognitive process are well established, the mechanism of selection process is the point of contention. To study the effect of selection process on the information processing we performed functional neuroimaging on 23 healthy righthanded male subjects while performing a modified face word stroop task. The word processing area did not show any attention dependent changes in the level of activity whereas the activity of face processing area was higher when the faces were target, but there was no decrease in baseline activity when faces were distractors. Our results suggest that during selective attention there is no biasing of sensory processing for automatically processed stimuli like words whereas there is amplification of task relevant information when stimuli are processed in controlled manner.