Abstract
The steady-state visual evoked potential (SSVEP), an
electrophysiological marker of attentional resource allocation,
has recently been demonstrated to serve as a neural signature of
emotional content extraction from a rapid serial visual
presentation (RSVP). SSVEP amplitude was reduced for streams of
emotional relative to neutral scenes passively viewed at 6 Hz
(∼167 ms per image), but it was enhanced for emotional relative
to neutral scenes when viewed as 4 Hz RSVP (250 ms per image).
Here, we investigated whether these seemingly contradictory
observations may be related to different dynamics in the
allocation of attentional resources as a consequence of
stimulation frequency. To this end, we advanced our distraction
paradigm by presenting a visual foreground task consisting of
randomly moving squares flickering at 15 Hz superimposed on
task-irrelevant RSVP streams shown at 6 or 4 Hz, which could
unpredictably switch from neutral to unpleasant content during
the trial or remained neutral. Critically, our findings
demonstrate that affective distractors captured attentional
resources more strongly than their neutral counterparts,
irrespective of whether they were presented at 6 or 4 Hz rate.
Moreover, the emotion-dependent attentional deployment from the
foreground task was temporally preceded by sustained sensory
facilitation in response to emotional background images.
Together, present findings provide evidence for rapid sustained
visual facilitation but a rather slow attentional bias in favor
of emotional distractors in early visual areas.
