The neural signature of extracting emotional content from rapid visual streams at multiple presentation rates: A cross-laboratory study.

The steady-state visual evoked potential (SSVEP), a neural signature of attentional resource allocation, is enhanced for affective compared to neutral visual scenes. Recently, it has been demonstrated that modulation of early visual cortex associated with viewing of unpleasant scenes presented in a rapid succession relies on emotional content extraction from each individual image shown in a rapid serial visual presentation (RSVP) at 6 Hz (~167 ms per image). Against expectations, the SSVEP was reduced when viewing visual streams of unpleasant compared to neutral scenes. Here, we investigated to what extent that finding was limited to the 6 Hz rate and whether it generalizes to pleasant pictures. We recorded SSVEPs elicited by RSVP of neutral and emotional scenes presented at 3, 4, 6.67, and 8.57 Hz rates. We demonstrated that SSVEP amplitudes were enhanced for unpleasant compared to neutral images with a presentation rate of 3, 4, and 8.57 Hz. By contrast, SSVEP decreased for both pleasant and unpleasant relative to neutral RSVP streams shown at 6.67 Hz. Our findings suggest that a linear superposition of ERPs evoked by each individual image in an RSVP may lead to SSVEP amplitude patterns that increase or decrease the power at the driving frequency, which in turn might produce the observed differential emotional amplitude modulations. The results provide new methodological considerations for investigating temporal dynamics of early visual cortex modulation during sustained perception of affective scenes with SSVEP using RSVP paradigms.