Competition for attentional resources between low spatial frequency content of emotional images and a foreground task in early visual cortex.

Low spatial frequency (LSF) image content has been proposed to play a superior functional role in emotional content extraction via the magnocellular pathway biasing attentional resources toward emotional content in visual cortex. We investigated whether emotionally unpleasant complex images that were presented either unfiltered or with LSF content only in the background while subjects performed a foreground task will withdraw more attentional resources from the task compared to unemotional, neutral images (distraction paradigm). We measured steady-state visual evoked potentials (SSVEPs) driven by flickering stimuli of a foreground task. Unfiltered unpleasant images resulted in a significant reduction of SSVEP amplitude compared to neutral images. No statistically significant differences were found with LSF background images. In a behavioral control experiment, we found no significant differences for complexity ratings between unfiltered and LSF pictures. Content identification was possible for unfiltered and LSF picture (correct responses > 74%). An additional EEG study examined typical emotion-related components for complex images presented either as unfiltered, LSF, or high spatial frequency (HSF, as an additional control) filtered, unpleasant, and neutral images. We found a significant main effect of emotional valence in the early posterior negativity. Late positive potential differences were only found for unfiltered and HSF images. Results suggest that, while LSF content is sufficient to allow for content and emotional cue extraction when images were presented alone, LSF content is not salient enough to serve as emotional distractor that withdraws attentional resources from a foreground task in early visual cortex.