Early ERP Modulation for Task-Irrelevant Subliminal Faces

Abstract

A number of investigations have reported that emotional faces can be processed subliminally, and that they give rise to specific patterns of brain activation in the absence of awareness. Recent event-related potential (ERP) studies have suggested that electrophysiological differences occur early in time (<200 ms) in response to backward-masked emotional faces. These findings have been taken as evidence of a rapid non-conscious pathway, which would allow threatening stimuli to be processed rapidly and subsequently allow appropriate avoidance action to be taken. However, for this to be the case, subliminal processing should arise even if the threatening stimulus is not attended. This point has in fact not yet been clearly established. In this ERP study, we investigated whether subliminal processing of fearful faces occurs outside the focus of attention. Fourteen healthy participants performed a line judgment task while fearful and non-fearful (happy or neutral) faces were presented both subliminally and supraliminally. ERPs were compared across the four experimental conditions (i.e., subliminal and supraliminal; fearful and non-fearful). The earliest differences between fearful and non-fearful faces appeared as an enhanced posterior negativity for the former at 170 ms (the N170 component) over right temporo-occipital electrodes. This difference was observed for both subliminal (p < 0.05) and supraliminal presentations (p < 0.01). Our results confirm that subliminal processing of fearful faces occurs early in the course of visual processing, and more importantly, that this arises even when the subject's attention is engaged in an incidental task.

The NMDA antagonist ketamine and the 5-HT agonist psilocybin produce dissociable effects on structural encoding of emotional face expressions

“…This means that we cannot infer from the discrimination threshold task that 10 ms is truly non-conscious for the processing of happy faces. However, recent ERP studies confirmed presentation times below 20 ms for non-conscious processing of happy faces (Balconi and Lucchiari 2008;Pegna et al 2011;Smith 2011). Therefore, it is conceivable to assume that presentation times of 10 ms as used in our ERP experiment are really non-conscious also for the processing of happy faces.…”

“…Recent studies used event-related potential (ERP) recording to investigate the time course of non-conscious and conscious emotional face processing (Pegna et al 2011;Smith 2011). Studies of ERPs generated by faces often focus on key components such as the P100 and the face-sensitive N170.…”

Gender differences in subliminal affective face priming: A high-density ERP study

“…Several ERP studies have suggested that ERP components, such as N2/P3 recorded from a midline site, are enhanced more by subliminally presented fearful faces than by supraliminally presented fearful faces [14,[29][30][31][32][33]. Furthermore, Pegna et al [34] reported that subliminally presented fearful faces elicited larger N170 amplitudes than did supraliminally presentation of fearful faces. These findings indicate a double dissociation for subliminal versus supraliminal processing of fearful faces [32], raising the possibility that subliminally presented fearful face stimuli may affect the perception of subsequently presented supraliminal face stimuli via subcortical visual pathways.…”

Processing of masked and unmasked emotional faces under different attentional conditions: an electrophysiological investigation

“…Along these lines, electrophysiological studies using face stimuli have provided evidence that faces can be processed at an early stage and without awareness both in healthy controls (e.g., Kiss and Eimer, 2008 ; Pegna et al, 2008 , 2011 ) and in patients with cortical blindness ( Gonzalez Andino et al, 2009 ; Del Zotto et al, 2013 ). Using a backward masking paradigm in healthy participants, Kiss and Eimer (2008) found that both subliminal and supraliminal fearful faces produced an enhanced early frontal positivity compared to neutral faces between 140 and 180 ms post-stimulus.…”