Poster B100, Sunday, March 25, 8:00-10:00 am, Exhibit Hall C
Retinotopically asymmetric effects of attentional load on early visual processing
Karsten Rauss1, Laura Herde1, Mona Schönauer1; 1University of Tuebingen, Germany
It remains disputed whether attention affects the earliest cortical stages of visual processing. In previous studies, we reported that attentional load at fixation modulates the initial component of the visual evoked potential (VEP), the retinotopic C1, but only for stimuli in the upper visual field. We proposed that known differences in spatial-frequency sensitivity between upper and lower visual field could explain such asymmetries. In the present study, we tested this proposal using high-density EEG. We first mapped VEPs in response to arrays of high-contrast line-elements with different spatial frequencies. The stimuli yielding maximum C1 responses in the upper and lower visual field in each subject were then used as peripheral distractors while subjects performed low- vs. high-load target detection on rapidly presented stimuli at fixation. As expected, we observed the previously elusive reduction of the C1 under high load in the lower visual field. However, we could not replicate our earlier finding of such a modulation in the upper visual field using individually optimized stimuli. We conclude that attentional load can affect early visual processing across the whole visual field; but that the stimulus features based on which such early filtering occurs may differ between upper and lower visual field.
Topic Area: PERCEPTION & ACTION: Vision