The Effect of Affective Context on Visuocortical Processing of Neutral Faces in Social Anxiety

Abstract

It has been demonstrated that verbal context information alters the neural processing of ambiguous faces such as faces with no apparent facial expression. In social anxiety, neutral faces may be implicitly threatening for socially anxious individuals due to their ambiguous nature, but even more so if these neutral faces are put in self-referential negative contexts. Therefore, we measured event-related brain potentials (ERPs) in response to neutral faces which were preceded by affective verbal information (negative, neutral, positive). Participants with low social anxiety (LSA; n = 23) and high social anxiety (HSA; n = 21) were asked to watch and rate valence and arousal of the respective faces while continuous EEG was recorded. ERP analysis revealed that HSA showed elevated P100 amplitudes in response to faces, but reduced structural encoding of faces as indexed by reduced N170 amplitudes. In general, affective context led to an enhanced early posterior negativity (EPN) for negative compared to neutral facial expressions. Moreover, HSA compared to LSA showed enhanced late positive potentials (LPP) to negatively contextualized faces, whereas in LSA this effect was found for faces in positive contexts. Also, HSA rated faces in negative contexts as more negative compared to LSA. These results point at enhanced vigilance for neutral faces regardless of context in HSA, while structural encoding seems to be diminished (avoidance). Interestingly, later components of sustained processing (LPP) indicate that LSA show enhanced visuocortical processing for faces in positive contexts (happy bias), whereas this seems to be the case for negatively contextualized faces in HSA (threat bias). Finally, our results add further new evidence that top-down information in interaction with individual anxiety levels can influence early-stage aspects of visual perception.

Keywords: EEG/ERP; ERPs (Event-Related Potentials); context effects; face processing; social anxiety.

Figure 1

Schematic of an experimental trial. A fixation cross was shown during inter-trial interval (ITI), which lasted randomly 2 and 3 s.

Figure 2

Illustration of the P100 component averaged across left and right occipital electrode clusters per experimental group (HSA vs. LSA) for negatively, neutrally, and positively contextualized faces. Overall, P100 amplitudes are enhanced in HSA compared to LSA.

Figure 3

Illustration of the N170 component averaged across left and right occipital electrode clusters per experimental group (HSA vs. LSA) for negatively, neutrally, and positively contextualized faces. Overall, N170 amplitudes are diminished in HSA compared to LSA.

Figure 4

(A) Illustration of the EPN component (260–320 ms, see hatched box) averaged across medial occipital electrode cluster for both groups. (B) On a back view of the model head the scalp potential map of the difference waves “negative-neutral” and “positive-neutral” are given. No group differences emerged, but enhanced EPN was observed for negative and positive contextualized faces.

Figure 5

Illustration of the LPP component averaged across medial-central sensor cluster for the three contextual conditions per group. (A) Enhanced LPP amplitudes were observed for positively contextualized compared to neutrally contextualized faces in LSA, but for negatively contextualized faces in HSA. (B) Scalp potential maps of the difference waves “negative-neutral” and “positive-neutral” for the LPP component are given on a top view of the model head.

Figure 6

Mean ratings (+SEM) of arousal (A) and valence (B) for faces in negative, neutral, and positive contexts, separated per group. Group differences emerged for the negatively contextualized faces, only. ^*Indicates p-values < 0.05.