Relative expertise affects N170 during selective attention to superimposed face-character images

Electrophysiological correlates of face and object perception: A comparative analysis of 2D laboratory and virtual reality conditions

Human face perception is a specialized visual process with inherent social significance. The neural mechanisms reflecting this intricate cognitive process have evolved in spatially complex and emotionally rich environments. Previous research using VR to transfer an established face perception paradigm to realistic conditions has shown that the functional properties of face-sensitive neural correlates typically observed in the laboratory are attenuated outside the original modality. The present study builds on these results by comparing the perception of persons and objects under conventional laboratory (PC) and realistic conditions in VR. Adhering to established paradigms, the PC- and VR modalities both featured images of persons and cars alongside standard control images. To investigate the individual stages of realistic face processing, response times, the typical face-sensitive N170 component, and relevant subsequent components (L1, L2; pre-, post-response) were analyzed within and between modalities. The between-modality comparison of response times and component latencies revealed generally faster processing under realistic conditions. However, the obtained N170 latency and amplitude differences showed reduced discriminative capacity under realistic conditions during this early stage. These findings suggest that the effects commonly observed in the lab are specific to monitor-based presentations. Analyses of later and response-locked components showed specific neural mechanisms for identification and evaluation are employed when perceiving the stimuli under realistic conditions, reflected in discernible amplitude differences in response to faces and objects beyond the basic perceptual features. Conversely, the results do not provide evidence for comparable stimulus-specific perceptual processing pathways when viewing pictures of the stimuli under conventional laboratory conditions.

Real-life relevant face perception is not captured by the N170 but reflected in later potentials: A comparison of 2D and virtual reality stimuli

The perception of faces is one of the most specialized visual processes in the human brain and has been investigated by means of the early event-related potential component N170. However, face perception has mostly been studied in the conventional laboratory, i.e., monitor setups, offering rather distal presentation of faces as planar 2D-images. Increasing spatial proximity through Virtual Reality (VR) allows to present 3D, real-life-sized persons at personal distance to participants, thus creating a feeling of social involvement and adding a self-relevant value to the presented faces. The present study compared the perception of persons under conventional laboratory conditions (PC) with realistic conditions in VR. Paralleling standard designs, pictures of unknown persons and standard control images were presented in a PC- and a VR-modality. To investigate how the mechanisms of face perception differ under realistic conditions from those under conventional laboratory conditions, the typical face-specific N170 and subsequent components were analyzed in both modalities. Consistent with previous laboratory research, the N170 lost discriminatory power when translated to realistic conditions, as it only discriminated faces and controls under laboratory conditions. Most interestingly, analysis of the later component [230–420 ms] revealed more differentiated face-specific processing in VR, as indicated by distinctive, stimulus-specific topographies. Complemented by source analysis, the results on later latencies show that face-specific neural mechanisms are applied only under realistic conditions (A video abstract is available in the Supplementary material and via YouTube: https://youtu.be/TF8wiPUrpSY).

The spatiotemporal characteristics of N170s for faces and words: A meta-analysis study

N170 is a negative event-related potential (ERP) component in response to visual stimuli, such as faces. It remains controversial whether N170 reflects the specific processing of faces or can also be elicited by objects of expertise (e.g., words). In this research, we conducted a meta-analysis for the spatiotemporal characteristics of N170 of face and word stimuli from 24 studies in which both stimuli were presented for each subject. We observed that (1) both face and word stimuli can elicit conspicuous N170s and that there was no difference between the amplitude of face-N170 and word-N170; (2) there is no difference in the latencies between the two N170s; and (3) both N170s are distributed in the occipitotemporal regions but with a reversed hemispheric distribution pattern-face-N170 is more negative in the right than left occipitotemporal regions, while word-N170 is the opposite. These results showed that the face- and word-N170s are qualitatively the same but have different hemispheric lateralization advantages-N170 might be a general neural index of the expertise-dependent object-recognition process in occipitotemporal regions.

Symmetrical and Asymmetrical Interactions between Facial Expressions and Gender Information in Face Perception

To investigate the interaction between facial expressions and facial gender information during face perception, the present study matched the intensities of the two types of information in face images and then adopted the orthogonal condition of the Garner Paradigm to present the images to participants who were required to judge the gender and expression of the faces; the gender and expression presentations were varied orthogonally. Gender and expression processing displayed a mutual interaction. On the one hand, the judgment of angry expressions occurred faster when presented with male facial images; on the other hand, the classification of the female gender occurred faster when presented with a happy facial expression than when presented with an angry facial expression. According to the evoked-related potential results, the expression classification was influenced by gender during the face structural processing stage (as indexed by N170), which indicates the promotion or interference of facial gender with the coding of facial expression features. However, gender processing was affected by facial expressions in more stages, including the early (P1) and late (LPC) stages of perceptual processing, reflecting that emotional expression influences gender processing mainly by directing attention.