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

View Article: PubMed Central

ABSTRACT

In order to investigate the interactions between non-spatial selective attention, awareness and emotion processing, we carried out an ERP study using a backward masking paradigm, in which angry, fearful, happy, and neutral facial expressions were presented, while participants attempted to detect the presence of one or the other category of facial expressions in the different experimental blocks. ERP results showed that negative emotions enhanced an early N170 response over temporal-occipital leads in both masked and unmasked conditions, independently of selective attention. A later effect arising at the P2 was linked to awareness. Finally, selective attention was found to affect the N2 and N3 components over occipito-parietal leads. Our findings reveal that (i) the initial processing of facial expressions arises prior to attention and awareness; (ii) attention and awareness give rise to temporally distinct periods of activation independently of the type of emotion with only a partial degree of overlap; and (iii) selective attention appears to be influenced by the emotional nature of the stimuli, which in turn impinges on unconscious processing at a very early stage. This study confirms previous reports that negative facial expressions can be processed rapidly, in absence of visual awareness and independently of selective attention. On the other hand, attention and awareness may operate in a synergistic way, depending on task demand.

No MeSH data available.


(A) Masked presentation; (B) Unmasked presentation. Both figures depict grand average ERPs, merged across electrodes ROI of N170 and between attentive and inattentive conditions (above); Scalp-Current-Density maps between 160 and 190 ms after the presentation of emotional stimuli, corresponding to N170 time window (below). Each ERP (and map) represents a different emotional condition: Anger (A—black), Fear (F—red), Happiness (H—blue), neutral (N—green).
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Figure 2: (A) Masked presentation; (B) Unmasked presentation. Both figures depict grand average ERPs, merged across electrodes ROI of N170 and between attentive and inattentive conditions (above); Scalp-Current-Density maps between 160 and 190 ms after the presentation of emotional stimuli, corresponding to N170 time window (below). Each ERP (and map) represents a different emotional condition: Anger (A—black), Fear (F—red), Happiness (H—blue), neutral (N—green).

Mentions: Unmasked pictures produced a greater amplitude compared to masked faces [“Presentation”: F(1,13) = 31.35, MSE = 9.75, ε = 1, p < 0.0001, = 0.71; mean values: –5.7 and –4 μV]. Negative facial expressions increased significantly the amplitude of this component compared to pleasant faces [“Emotion”: F(3,39) = 6.38, MSE = 4.99, ε = 0.58, p < 0.009, = 0.33; mean values: A = –5.24 μV and F = 5.36 μV vs. H = –4.63 μV and n = –4.23 μV; post hoc comparisons: ps < 0.05]. The interaction of “Presentation × Emotions” [F(3,39) = 4.1, MSE = 2.56, ε = 0.73, p < 0.025, = 0.24] progressively showed an increased negativity across emotions, from neutral to angry faces (N = –3 μV < H = –3.79 μV < F = –4.6 μV and A = –4.77 μV; ps < 0.02) only in the masked condition (Figure 2). In the unmasked condition, only fearful faces (–6.12 μV) elicited a greater negativity compared to happy (–5.48 μV) and neutral facial (–5.44 μV) expressions (post hoc comparisons: ps < 0.04).


Processing of masked and unmasked emotional faces under different attentional conditions: an electrophysiological investigation
(A) Masked presentation; (B) Unmasked presentation. Both figures depict grand average ERPs, merged across electrodes ROI of N170 and between attentive and inattentive conditions (above); Scalp-Current-Density maps between 160 and 190 ms after the presentation of emotional stimuli, corresponding to N170 time window (below). Each ERP (and map) represents a different emotional condition: Anger (A—black), Fear (F—red), Happiness (H—blue), neutral (N—green).
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Related In: Results  -  Collection

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Figure 2: (A) Masked presentation; (B) Unmasked presentation. Both figures depict grand average ERPs, merged across electrodes ROI of N170 and between attentive and inattentive conditions (above); Scalp-Current-Density maps between 160 and 190 ms after the presentation of emotional stimuli, corresponding to N170 time window (below). Each ERP (and map) represents a different emotional condition: Anger (A—black), Fear (F—red), Happiness (H—blue), neutral (N—green).
Mentions: Unmasked pictures produced a greater amplitude compared to masked faces [“Presentation”: F(1,13) = 31.35, MSE = 9.75, ε = 1, p < 0.0001, = 0.71; mean values: –5.7 and –4 μV]. Negative facial expressions increased significantly the amplitude of this component compared to pleasant faces [“Emotion”: F(3,39) = 6.38, MSE = 4.99, ε = 0.58, p < 0.009, = 0.33; mean values: A = –5.24 μV and F = 5.36 μV vs. H = –4.63 μV and n = –4.23 μV; post hoc comparisons: ps < 0.05]. The interaction of “Presentation × Emotions” [F(3,39) = 4.1, MSE = 2.56, ε = 0.73, p < 0.025, = 0.24] progressively showed an increased negativity across emotions, from neutral to angry faces (N = –3 μV < H = –3.79 μV < F = –4.6 μV and A = –4.77 μV; ps < 0.02) only in the masked condition (Figure 2). In the unmasked condition, only fearful faces (–6.12 μV) elicited a greater negativity compared to happy (–5.48 μV) and neutral facial (–5.44 μV) expressions (post hoc comparisons: ps < 0.04).

View Article: PubMed Central

ABSTRACT

In order to investigate the interactions between non-spatial selective attention, awareness and emotion processing, we carried out an ERP study using a backward masking paradigm, in which angry, fearful, happy, and neutral facial expressions were presented, while participants attempted to detect the presence of one or the other category of facial expressions in the different experimental blocks. ERP results showed that negative emotions enhanced an early N170 response over temporal-occipital leads in both masked and unmasked conditions, independently of selective attention. A later effect arising at the P2 was linked to awareness. Finally, selective attention was found to affect the N2 and N3 components over occipito-parietal leads. Our findings reveal that (i) the initial processing of facial expressions arises prior to attention and awareness; (ii) attention and awareness give rise to temporally distinct periods of activation independently of the type of emotion with only a partial degree of overlap; and (iii) selective attention appears to be influenced by the emotional nature of the stimuli, which in turn impinges on unconscious processing at a very early stage. This study confirms previous reports that negative facial expressions can be processed rapidly, in absence of visual awareness and independently of selective attention. On the other hand, attention and awareness may operate in a synergistic way, depending on task demand.

No MeSH data available.