Poster F4, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Attentional bias to rapid affective picture presentations at 4 and 6 Hz
Valeria Bekhtereva1, Matthias M. Müller1; 1University of Leipzig
Emotional stimuli are known to rapidly draw visual processing resources, even when they are task-irrelevant. Here we investigated the time-course of attentional resource bias from a primary visual task towards rapidly presented background streams of distractor-images which could switch from neutral to neutral or unpleasant content during the trial. Randomly moving squares flickering at 15 Hz were superimposed on image streams shown at 6 or 4 Hz (~167 or 250 ms per image). Subjects detected coherent motion in the flickering squares while ignoring the pictures. Steady-state visual evoked potentials (SSVEP), neural markers of attention allocation, were generated at the distinct frequencies of the task and picture streams, which allowed us to measure the temporal dynamics of the competition for processing resources in early visual cortex between the task and images. We found a decrease in SSVEP amplitudes at 15 Hz over several hundred milliseconds, signifying a withdrawal of attentional resources away from the task towards negative relative to neutral images. In parallel, background image streams shown at 4 and 6 Hz were also modulated as a function of emotional content. There were higher SSVEP amplitudes towards unpleasant vs neutral streams at 4 Hz, whereas the reverse SSVEP modulation was observed with 6 Hz streams. Taken together, our findings highlight the power of the SSVEP as a tool to investigating changes in visual cortex activity during rapid picture viewing, and also imply that temporal superposition of event-related potentials elicited by each individual image in a stream may drive SSVEP amplitude modulations.
Topic Area: ATTENTION: Spatial