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Early Left Parietal Activity Elicited by Direct Gaze: A High-Density EEG Study

View Article: PubMed Central - PubMed

ABSTRACT

Gaze is one of the most important cues for human communication and social interaction. In particular, gaze contact is the most primary form of social contact and it is thought to capture attention. A very early-differentiated brain response to direct versus averted gaze has been hypothesized. Here, we used high-density electroencephalography to test this hypothesis. Topographical analysis allowed us to uncover a very early topographic modulation (40–80 ms) of event-related responses to faces with direct as compared to averted gaze. This modulation was obtained only in the condition where intact broadband faces–as opposed to high-pass or low-pas filtered faces–were presented. Source estimation indicated that this early modulation involved the posterior parietal region, encompassing the left precuneus and inferior parietal lobule. This supports the idea that it reflected an early orienting response to direct versus averted gaze. Accordingly, in a follow-up behavioural experiment, we found faster response times to the direct gaze than to the averted gaze broadband faces. In addition, classical evoked potential analysis showed that the N170 peak amplitude was larger for averted gaze than for direct gaze. Taken together, these results suggest that direct gaze may be detected at a very early processing stage, involving a parallel route to the ventral occipito-temporal route of face perceptual analysis.

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Result of the additional behavioral experiment.Using the same material, the same paradigm than the EEG experiment and the same number of participants (N = 15), we asked participants to answer as quickly as possible to the gender of each pictures. Critically, the direct gaze condition with broadband filtering is performed significantly faster than its averted counterpart.
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pone.0166430.g002: Result of the additional behavioral experiment.Using the same material, the same paradigm than the EEG experiment and the same number of participants (N = 15), we asked participants to answer as quickly as possible to the gender of each pictures. Critically, the direct gaze condition with broadband filtering is performed significantly faster than its averted counterpart.

Mentions: Moreover, the analysis of RT in the additional behavioral experiment revealed also a main effect of the spatial filtering of the faces, with faster RT for the broadband faces (median RT = 572 ms, 604 ms, 602 ms, for BB, HSF, LSF pictures, respectively; F(2,28) = 8.65, p < .001, ηp2 = .38). In addition, the RT was faster for direct than averted gaze for the broadband faces (mean RT for direct gaze = 560ms, for averted gaze = 584ms, t(14) = 2.38, p = .036, Cohen's d = 0.21) (Fig 2). The gaze direction effect was not significant for the LSF (mean RT for direct gaze = 596ms, for averted gaze = 608 ms; t<1) and the HSF faces (mean RT for direct gaze = 596ms, for averted gaze = 608 ms; t<1).


Early Left Parietal Activity Elicited by Direct Gaze: A High-Density EEG Study
Result of the additional behavioral experiment.Using the same material, the same paradigm than the EEG experiment and the same number of participants (N = 15), we asked participants to answer as quickly as possible to the gender of each pictures. Critically, the direct gaze condition with broadband filtering is performed significantly faster than its averted counterpart.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120811&req=5

pone.0166430.g002: Result of the additional behavioral experiment.Using the same material, the same paradigm than the EEG experiment and the same number of participants (N = 15), we asked participants to answer as quickly as possible to the gender of each pictures. Critically, the direct gaze condition with broadband filtering is performed significantly faster than its averted counterpart.
Mentions: Moreover, the analysis of RT in the additional behavioral experiment revealed also a main effect of the spatial filtering of the faces, with faster RT for the broadband faces (median RT = 572 ms, 604 ms, 602 ms, for BB, HSF, LSF pictures, respectively; F(2,28) = 8.65, p < .001, ηp2 = .38). In addition, the RT was faster for direct than averted gaze for the broadband faces (mean RT for direct gaze = 560ms, for averted gaze = 584ms, t(14) = 2.38, p = .036, Cohen's d = 0.21) (Fig 2). The gaze direction effect was not significant for the LSF (mean RT for direct gaze = 596ms, for averted gaze = 608 ms; t<1) and the HSF faces (mean RT for direct gaze = 596ms, for averted gaze = 608 ms; t<1).

View Article: PubMed Central - PubMed

ABSTRACT

Gaze is one of the most important cues for human communication and social interaction. In particular, gaze contact is the most primary form of social contact and it is thought to capture attention. A very early-differentiated brain response to direct versus averted gaze has been hypothesized. Here, we used high-density electroencephalography to test this hypothesis. Topographical analysis allowed us to uncover a very early topographic modulation (40&ndash;80 ms) of event-related responses to faces with direct as compared to averted gaze. This modulation was obtained only in the condition where intact broadband faces&ndash;as opposed to high-pass or low-pas filtered faces&ndash;were presented. Source estimation indicated that this early modulation involved the posterior parietal region, encompassing the left precuneus and inferior parietal lobule. This supports the idea that it reflected an early orienting response to direct versus averted gaze. Accordingly, in a follow-up behavioural experiment, we found faster response times to the direct gaze than to the averted gaze broadband faces. In addition, classical evoked potential analysis showed that the N170 peak amplitude was larger for averted gaze than for direct gaze. Taken together, these results suggest that direct gaze may be detected at a very early processing stage, involving a parallel route to the ventral occipito-temporal route of face perceptual analysis.

No MeSH data available.


Related in: MedlinePlus