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Free keywords:
Affective stimulus processing; Attentional resource competition;
Early posterior negativity (EPN); Low spatial frequencies;
Magnocellular pathway; Steady-state visual evoked potential
(SSVEP)
Abstract:
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.
