Human sex differences in emotional processing of own-race and other-race faces

Reduced spatial frequency differentiation and sex-related specificities in fearful face detection in autism: Insights from EEG and the predictive brain model

Face processing relies on predictive processes driven by low spatial frequencies (LSF) that convey coarse information prior to fine information conveyed by high spatial frequencies. However, autistic individuals might have atypical predictive processes, contributing to facial processing difficulties. This may be more normalized in autistic females, who often exhibit better socio-communicational abilities than males. We hypothesized that autistic females would display a more typical coarse-to-fine processing for socio-emotional stimuli compared to autistic males. To test this hypothesis, we asked adult participants (44 autistic, 51 non-autistic) to detect fearful faces among neutral faces, filtered in two orders: from coarse-to-fine (CtF) and from fine-to-coarse (FtC). Results show lower d' values and longer reaction times for fearful detection in autism compared to non-autistic (NA) individuals, regardless of the filtering order. Both groups presented shorter P100 latency after CtF compared to FtC, and larger amplitude for N170 after FtC compared to CtF. However, autistic participants presented a reduced difference in source activity between CtF and FtC in the fusiform. There was also a more spatially spread activation pattern in autistic females compared to NA females. Finally, females had faster P100 and N170 latencies, as well as larger occipital activation for FtC sequences than males, irrespective of the group. Overall, the results do not suggest impaired predictive processes from LSF in autism despite behavioral differences in fear detection. However, they do indicate reduced brain modulation by spatial frequency in autism. In addition, the findings highlight sex differences that warrant consideration in understanding autistic females.

Neural timing of the other-race effect across the lifespan: A review

Face race influences the way we process faces, so that faces of a different ethnic group are processed for identity less efficiently than faces of one's ethnic group - a phenomenon known as the Other-Race Effect (ORE). Although widely replicated, the ORE is still poorly characterized in terms of its development and the underlying mechanisms. In the last two decades, the Event-Related Potential (ERP) technique has brought insight into the mechanisms underlying the ORE and has demonstrated potential to clarify its development. Here, we review the ERP evidence for a differential neural processing of own-race and other-race faces throughout the lifespan. In infants, race-related processing differences emerged at the N290 and P400 (structural encoding) stages. In children, race affected the P100 (early processing, attention) perceptual stage and was implicitly encoded at the N400 (semantic processing) stage. In adults, processing difficulties for other-race faces emerged at the N170 (structural encoding), P200 (configuration processing) and N250 (accessing individual representations) perceptual stages. Early in processing, race was implicitly encoded from other-race faces (N100, P200 attentional biases) and in-depth processing preferentially applied to own-race faces (N200 attentional bias). Encoding appeared less efficient (Dm effects) and retrieval less recollection-based (old/new effects) for other-race faces. Evidence admits the contribution of perceptual, attentional, and motivational processes to the development and functioning of the ORE, offering no conclusive support for perceptual or socio-cognitive accounts. Cross-racial and non-cross-racial studies provided convergent evidence. Future research would need to include less represented ethnic populations and the developmental population.

Anodal tDCS effects over the left dorsolateral prefrontal cortex (L-DLPFC) on the rating of facial expression: evidence for a gender-specific effect

The accurate recognition of others' facial expressions is a core skill for social interactions. The left Dorsolateral Prefrontal Cortex (L-DLPFC) represents a key node in the network for facial emotion recognition. However, its specific role is still under debate. As such, the aim of the current neuromodulation study was to assess the causal role of the L-DLPFC in humans' rating of facial expressions of emotions and implicit attitudes toward other races. In this sham-controlled single-blind between-subject experiment, we offline administered L-DLPFC transcranial direct current stimulation (tDCS) to 69 healthy participants who were divided into three groups of 23 (each receiving anodal 1 mA tDCS, anodal 2 mA tDCS, or Sham), before completing an "Emotion Rating task and two Implicit Association Tests (IATs). The former required the intensity rating of 192 faces (half black and half white) displaying happiness, sadness, anger, or fear. The IATs were designed to assess participants' automatic associations of positive or negative attributes with racial contents. Results on the Emotion Rating task showed participants' gender-specific effect of tDCS. Specifically, a gender bias, with only males showing a tendency to underestimate negative emotions was found in Sham, and absent in the tDCS groups. When considering the race of the stimuli, females but not males in Sham exhibited a racial bias, that is, the tendency to overestimate negative emotions of other-race faces. Again, the bias disappeared in the tDCS groups. Concerning the IATs, no significant effects emerged. We conclude that the L-DLPFC plays a critical role in humans' rating of facial expressions, and for variability in other-race emotional judgements. These results shed light on the neural bases of the human emotional system and its gender-related differences, and have potential implications for interventional settings.

The timeline of mentalization: Distinguishing a two-phase process from mind detection to mind attribution

Mentalization is the ability to perceive other people's mental states. This research aimed to deepen our understanding of the underlying mechanisms while also exploring the timeline of the mentalization process. Two studies were conducted in which participants' electrophysiological activity was measured while elaborating Black and White (Study 1), or Italian (ingroup) and Romanian (outgroup), human and doll-like faces (Study 2). Moreover, in Study 2 the presented faces differed in their Facial Width-to-Height Ratio. Subsequently, an Implicit Mind Attribution Test (IMAT) measured the strength of the association of the same ingroup and outgroup human stimuli with mind and body-related words. Two different phases in the time course of the mentalization process emerged. An early ERP component (N170) indicated a first difference between doll-like, mindless and human, mindful targets, while a later ERP component (P300) represented the second stage of mentalization. In this stage, outgroup doll-like faces were elaborated more similarly to the outgroup human faces compared to the same stimuli of the ingroup. Moreover, only a positive correlation between the P300 and the IMAT emerged indicating that the differences in this later ERP component were related with an implicit behavioral measure of mind attribution. These results stipulate the timeline of the mentalization process that is defined by an initial moment of mind detection, in which mindful and mindless stimuli are differentiated for the first time, and a second phase of mind attribution, where the interplay of perceptual and contextual information determine the extraction of a mind from a face.

Emotional face prediction in rejection sensitive individuals: Evidence from event-related potentials

Human beings live in an uncertain world, but they continuously generate top-down predictions about emotional face information of other people around them. Although the prediction processing has repeatedly been investigated in the literature of prediction, little is known about the impact of rejection sensitive (RS) on individuals' emotional face prediction. To this end, high and low RS participants were asked to perform an identification task of emotional faces in which target faces were shown in either an angry or happy expression while their brain responses were recorded using an event-related potential (ERP) technique. The behavioral results suggested an effect of emotional face prediction. For the P100 component, low RS participants showed longer P100 peak latencies in the left than right hemisphere when they viewed predictable emotional faces. In addition, low RS participants showed larger N170 mean amplitudes for angry compared to happy faces when they perceived unpredictable faces, but not when these faces were predictable. This presumably reflected a sensibility to angry faces in the unpredictable trails. Interestingly, high RS participants did not demonstrate such a N170 difference, suggesting that high RS participants showed a reduced sensitivity to unpredictable angry faces. Furthermore, angry faces triggered increased LPP mean amplitudes compared to happy faces, which was consistent with the results of other ERP studies examining the processing of emotional faces. Finally, we observed significant negative correlations between behavioral and ERP prediction effect, indicating one consistency between the behavioral and electrophysiological data.

Security priming improves attentional processing to infant emotions among insecurely attached women: The different roles of supraliminal and subliminal priming

In two ERP experiments, we examined the attention-related mechanism involved in perceiving infant emotions following exposure to security priming. Specifically, we examined how security priming affected securely and insecurely attached women. We found that both supraliminal and subliminal security priming resulted in increased attention allocation in anxiously and avoidantly attached women but had no effect on securely attached women. Moreover, we also found that supraliminal and subliminal security priming differed in their effectiveness in increasing attention allocation among anxiously and avoidantly attached women. Supraliminal security priming were more effective for anxiously attached women, whereas subliminal security priming were more effective for avoidantly attached women. The implications of these findings and directions for future research are discussed.

The Perception of Facial Emotional Change in Social Anxiety: An ERP Study

Social anxiety is one of the psychological symptoms that most commonly occur in social interaction. Although previous behavioral studies have investigated the neutral-angry facial emotion change in social anxiety, none of the previous studies have, however, directly investigated the angry-neutral facial emotional change. Furthermore, less is known about the neural correlates of the facial emotion changes in individuals with social anxiety. The main goal of the present study was to explore the perception of facial emotional changes in individuals with social anxiety, using high temporal resolution event-related potential techniques. Behaviorally, accuracy in the angry-neutral facial emotional change trail was lower than that in the neutral-neutral case. Neurally, we found that the N170 amplitudes in angry-neutral facial emotional change trial were larger than those in the neutral-neutral case for high social anxiety (HAS) participants, probably reflecting that they might engage in more analytical processing of different facial elements. Interestingly, HSA participants showed smaller P200 left hemisphere amplitudes in the angry-neutral facial emotional change trial when compared with the neutral-neutral case, which suggested that they might have difficulties in processing emotions when they encounter these facial emotional changes. Finally, the late positive potential amplitudes in the neutral-angry and angry-neutral facial emotional change trials were smaller than those in the neutral-neutral case, regardless of the social anxiety. These results suggest that social anxiety influences the facial emotional changes mainly at an earlier stage of processing.

The Impact of Top-Down Prediction on Emotional Face Processing in Social Anxiety

There is evidence that people with social anxiety show abnormal processing of emotional faces. To investigate the impact of top-down prediction on emotional face processing in social anxiety, brain responses of participants with high and low social anxiety (LSA) were recorded, while they performed a variation of the emotional task, using high temporal resolution event-related potential techniques. Behaviorally, we reported an effect of prediction with higher accuracy for predictable than unpredictable faces. Furthermore, we found that participants with high social anxiety (HSA), but not with LSA, recognized angry faces more accurately than happy faces. For the P100 and P200 components, HSA participants showed enhanced brain activity for angry faces compared to happy faces, suggesting a hypervigilance to angry faces. Importantly, HSA participants exhibited larger N170 amplitudes in the right hemisphere electrodes than LSA participants when they observed unpredictable angry faces, but not when the angry faces were predictable. This probably reflects the top-down prediction improving the deficiency at building a holistic face representation in HSA participants.

Emotional correlates of unirhinal odour identification

It seems self-evident that smell profoundly shapes emotion, but less clear is the nature of this interaction. Here, we sought to determine whether the ability to identify odours co-varies with self-reported feelings of empathy and emotional expression recognition, as predicted if the two capacities draw on common resource. Thirty-six neurotypical volunteers were administered the Alberta Smell Test, the Interpersonal Reactivity Index and an emotional expression recognition task. Statistical analyses indicated that feelings of emotional empathy positively correlated with odour discrimination in right nostril, while the recognition of happy and fearful facial expressions positively correlated with odour discrimination in left nostril. These results uncover new links between olfactory discrimination and emotion which, given the ipsilateral configuration of the olfactory projections, point towards intra- rather than inter-hemispheric interaction. The results also provide novel support for the proposed lateralization of emotional empathy and the recognition of facial expression, and give reason to further explore the diagnostic sensitivity of smell tests because reduced sensitivity to others' emotions can mark the onset of certain neurological diseases.

Unconscious attention modulates the silencing effect of top-down predictions

The brain is considered to be proactive in that it continuously generates predictions about external environment stimuli. Recent Bayesian models of perception have demonstrated that prediction and attention operate synergistically to optimize stimulus processing. However, the relation between prediction and unconscious attention remains unclear given the relative neglect of unconscious attention in scholarly literatures. To investigate this issue, twenty participants (12 women) performed an orientation identification task in which a circular grating appeared either in the left or in the right visual field in a single 30-40min session, during which 64-channel EEG data were acquired. Behavioral results showed an unconscious-attended effect and a facilitated effect. Importantly, prediction-related P1 and N1 silencing effects were observed in the unconscious-attended condition, probably reflecting that unconscious attention improves the precision of top-down predictions at an early stage of processing, thereby increasing the synaptic gain of predictor neurons. Moreover, unlike the early ERP components, P3 revealed a reversed pattern of results, which displayed a silencing effect of prediction only in the unattended condition, suggesting that the influence of unconscious attention on the silencing effect may change over time.