Abstract
The level of attentional load in a current task is known to determine the extent to which an irrelevant stimulus will evoke a BOLD neural response in sensory cortex (Rees et al, 1997; Schwartz et al., 2005). Here we examined whether the level of attentional load in a central task modulated feature-specific representations in early visual cortex for an irrelevant stimulus. We measured responses to a task-irrelevant peripheral grating with one of two orthogonal orientations while participants performed a central RSVP task of varying attentional load, using fMRI and multivariate pattern analysis applied to V1–V3. The orientation of the irrelevant grating was classified significantly better than chance in both high and low attentional load conditions from responses in V1-V3. However accuracy was significantly higher under low versus high attentional load. This suggests that high attentional demand for a task at fixation modifies feature-specific neural representations of irrelevant peripheral stimuli in early visual cortex.