Electrophysiological correlates of the efficient detection of emotional facial expressions

Altered Brain Reactivity to Food Cues in Undergraduate Students with Disordered Eating Behaviors

PURPOSE

A growing body of evidence has shown that electroencephalography (EEG) is an interesting method of assessing the underlying brain physiology associated with disordered eating. Using EEG, we sought to evaluate brain reactivity to hyper-palatable food cues in undergraduate students with disordered eating behavior (DEB).

METHODS

After assessing the eating behaviors of twenty-six undergraduate students using the Eating Attitudes Test (EAT-26), electroencephalographic signals were recorded while the participants were presented with pictures of hyper-palatable food. The current study used a temporospatial principal component analysis (PCA) approach to identify event-related potential (ERP) responses that differed between DEB and non-DEB individuals.

RESULTS

A temporospatial PCA applied to the ERPs identified a positivity with a maximum amplitude at 347 ms at the occipital-temporal electrodes in response to pictures of hyper-palatable food. This positivity was correlated with the EAT-26 scores. Participants with DEB showed reduced positivities in this component compared with those without DEB.

CONCLUSION

Our findings may reflect greater motivated attention toward hyper-palatable food cues in undergraduate students with DEB. These results are an important step toward obtaining a more refined understanding of specific abnormalities related to reactivity to food cues in this population.

The effect of emotional arousal on visual attentional performance: a systematic review

Although the arousal elicited by emotional stimuli, similarly to valence, is an integrative part of emotion theories, previous studies and reviews mostly focused on the valence of a stimulus and rarely investigated the role of arousal. Here, I systematically searched for articles that used visual attentional paradigms, manipulated emotional arousal by auditory or visual, task-relevant or task-irrelevant stimuli, measured behavioral responses, ocular behavior, or neural correlates. I found that task-relevant arousing stimuli draw and hold attention regardless of the modality. In contrast, task-irrelevant arousing stimuli impaired task performance. However, when the emotional content precedes the task or it is presented for a longer duration, arousal increased performance. Future directions on how research could address the remaining questions are discussed.

Influence of stimulus manipulation on conscious awareness of emotional facial expressions in the match-to-sample paradigm

The conscious perception of emotional facial expressions plays an indispensable role in social interaction. However, previous psychological studies have reported inconsistent findings regarding whether conscious awareness is greater for emotional expressions than for neutral expressions. Furthermore, whether this phenomenon is attributable to emotional or visual factors remains unknown. To investigate these issues, we conducted five psychological experiments to test the conscious perception of emotional and neutral facial expressions using the match-to-sample paradigm. Facial stimuli were momentarily presented in the peripheral visual fields while participants read simultaneously presented letters in the central visual fields. The participants selected a perceived face from nine samples. The results of all experiments demonstrated that emotional expressions were more accurately identified than neutral expressions. Furthermore, Experiment 4 showed that angry expressions were identified more accurately than anti-angry expressions, which expressed neutral emotions with comparable physical changes to angry expressions. Experiment 5, testing the interaction between emotional expression and face direction, showed that angry expressions looking toward participants were more accurately identified than those looking away from participants, even though they were physically identical. These results suggest that the conscious awareness of emotional facial expressions is enhanced by their emotional significance.

How are emotional facial expressions detected rapidly and accurately? A diffusion model analysis

Previous psychological studies have shown that people detect emotional facial expressions more rapidly and accurately than neutral facial expressions. However, the cognitive mechanisms underlying the efficient detection of emotional facial expressions remain unclear. To investigate this issue, we used diffusion model analyses to estimate the cognitive parameters of a visual search task in which participants detected faces with normal expressions of anger and happiness and their anti-expressions within a crowd of neutral faces. The anti-expressions were artificially created to control the visual changes of facial features but were usually recognized as emotionally neutral. We tested the hypothesis that the emotional significance of the target's facial expressions modulated the non-decisional time and the drift rate. We also conducted an exploratory investigation of the effect of facial expressions on threshold separation. The results showed that the non-decisional time was shorter, and the drift rate was larger for targets with normal expressions than with anti-expressions. Subjective emotional arousal ratings of facial targets were negatively related to the non-decisional time and positively associated with the drift rate. In addition, the threshold separation was larger for normal expressions than for anti-expressions and positively associated with arousal ratings for facial targets. These results suggest that the efficient detection of emotional facial expressions is accomplished via the faster and more cautious accumulation of emotional information of facial expressions which is initiated more rapidly by enhanced attentional allocation.

Rapid detection of neutral faces associated with emotional value

Swift detection of faces with emotional meaning underlies fruitful social relationships. Although previous studies using a visual search paradigm have demonstrated rapid detection of emotional facial expressions, whether it is attributable to emotional/motivational significance remains to be clarified. We examined this issue by excluding the influence of visual factors on the rapid detection of faces with emotional meaning. First, participants were engaged in an associative learning task wherein neutral faces were associated with either monetary rewards, monetary punishments, or zero outcome in order for the neutral faces to acquire positive, negative, and no emotional value, respectively. Then, during the visual search task, the participants detected a target-neutral face associated with high reward or punishment from among newly presented neutral faces. In Experiment 1, neutral faces associated with high reward and punishment values were more rapidly detected than those without monetary outcomes. In Experiment 2, highly rewarded and highly punished neutral faces were more rapidly detected than neutral faces associated with low monetary reward/punishment. Analyses of ratings confirmed that the learned neutral faces acquired emotional value, and the reaction times were negatively related to arousal ratings. These results suggest that the emotional/motivational significance promotes the rapid detection of emotional faces.

Schizotypy is associated with difficulties detecting emotional facial expressions

People with schizophrenia or subclinical schizotypal traits exhibit impaired recognition of facial expressions. However, it remains unclear whether the detection of emotional facial expressions is impaired in people with schizophrenia or high levels of schizotypy. The present study examined whether the detection of emotional facial expressions would be associated with schizotypy in a non-clinical population after controlling for the effects of IQ, age, and sex. Participants were asked to respond to whether all faces were the same as quickly and as accurately as possible following the presentation of angry or happy faces or their anti-expressions among crowds of neutral faces. Anti-expressions contain a degree of visual change that is equivalent to that of normal emotional facial expressions relative to neutral facial expressions and are recognized as neutral expressions. Normal expressions of anger and happiness were detected more rapidly and accurately than their anti-expressions. Additionally, the degree of overall schizotypy was negatively correlated with the effectiveness of detecting normal expressions versus anti-expressions. An emotion-recognition task revealed that the degree of positive schizotypy was negatively correlated with the accuracy of facial expression recognition. These results suggest that people with high levels of schizotypy experienced difficulties detecting and recognizing emotional facial expressions.

Impairment of emotional expression detection after unilateral medial temporal structure resection

Detecting emotional facial expressions is an initial and indispensable component of face-to-face communication. Neuropsychological studies on the neural substrates of this process have shown that bilateral amygdala lesions impaired the detection of emotional facial expressions. However, the findings were inconsistent, possibly due to the limited number of patients examined. Furthermore, whether this processing is based on emotional or visual factors of facial expressions remains unknown. To investigate this issue, we tested a group of patients (n = 23) with unilateral resection of medial temporal lobe structures, including the amygdala, and compared their performance under resected- and intact-hemisphere stimulation conditions. The participants were asked to detect normal facial expressions of anger and happiness, and artificially created anti-expressions, among a crowd with neutral expressions. Reaction times for the detection of normal expressions versus anti-expressions were shorter when the target faces were presented to the visual field contralateral to the intact hemisphere (i.e., stimulation of the intact hemisphere; e.g., right visual field for patients with right hemispheric resection) compared with the visual field contralateral to the resected hemisphere (i.e., stimulation of the resected hemisphere). Our findings imply that the medial temporal lobe structures, including the amygdala, play an essential role in the detection of emotional facial expressions, according to the emotional significance of the expressions.

Cultural differences in food detection

The ability to detect food plays an indispensable role in our survival and wellbeing. Previous psychological studies have revealed that food is detected more rapidly than non-food items. However, whether the detection of food could be modulated by cultural factors remains unknown. We investigated this issue in the present study using a visual search paradigm with Polish and Japanese participants. Photographs of international fast food, domestic Japanese food, or kitchen tools were presented alongside images of non-food distractors (cars). Participants were asked to judge whether the stimuli were all identical or not. The reaction time data showed that participants from both cultures detected food more rapidly than kitchen tools. Japanese participants detected fast food more rapidly than Japanese food, whereas Polish participants did not display such differences between food types. These results suggest that rapid detection of food is universal, but is modulated by cultural experiences.

Older adults detect happy facial expressions less rapidly

Previous experimental psychology studies based on visual search paradigms have reported that young adults detect emotional facial expressions more rapidly than emotionally neutral expressions. However, it remains unclear whether this holds in older adults. We investigated this by comparing the abilities of young and older adults to detect emotional and neutral facial expressions while controlling the visual properties of faces presented (termed anti-expressions) in a visual search task. Both age groups detected normal angry faces more rapidly than anti-angry faces. However, whereas young adults detected normal happy faces more rapidly than anti-happy faces, older adults did not. This suggests that older adults may not be easy to detect or focusing attention towards smiling faces appearing peripherally.

Spatiotemporal commonalities of fronto-parietal activation in attentional orienting triggered by supraliminal and subliminal gaze cues: An event-related potential study

Eye gaze triggers attentional shifts with and without conscious awareness. It remains unclear whether the spatiotemporal patterns of electric neural activity are the same for conscious and unconscious attentional shifts. Thus, the present study recorded event-related potentials (ERPs) and evaluated the neural activation involved in attentional orienting induced by subliminal and supraliminal gaze cues. Nonpredictive gaze cues were presented in the central field of vision, and participants were asked to detect a subsequent peripheral target. The mean reaction time was shorter for congruent gaze cues than for incongruent gaze cues under both presentation conditions, indicating that both types of cues reliably trigger attentional orienting. The ERP analysis revealed that averted versus straight gaze induced greater negative deflection in the bilateral fronto-central and temporal regions between 278 and 344 ms under both supraliminal and subliminal presentation conditions. Supraliminal cues, irrespective of gaze direction, induced a greater negative amplitude than did subliminal cues at the right posterior cortices at a peak of approximately 170 ms and in the 200-300 ms. These results suggest that similar spatial and temporal fronto-parietal activity is involved in attentional orienting triggered by both supraliminal and subliminal gaze cues, although inputs from different visual processing routes (cortical and subcortical regions) may trigger activity in the attentional network.

Impaired detection of happy facial expressions in autism

The detection of emotional facial expressions plays an indispensable role in social interaction. Psychological studies have shown that typically developing (TD) individuals more rapidly detect emotional expressions than neutral expressions. However, it remains unclear whether individuals with autistic phenotypes, such as autism spectrum disorder (ASD) and high levels of autistic traits (ATs), are impaired in this ability. We examined this by comparing TD and ASD individuals in Experiment 1 and individuals with low and high ATs in Experiment 2 using the visual search paradigm. Participants detected normal facial expressions of anger and happiness and their anti-expressions within crowds of neutral expressions. In Experiment 1, reaction times were shorter for normal angry expressions than for anti-expressions in both TD and ASD groups. This was also the case for normal happy expressions vs. anti-expressions in the TD group but not in the ASD group. Similarly, in Experiment 2, the detection of normal vs. anti-expressions was faster for angry expressions in both groups and for happy expressions in the low, but not high, ATs group. These results suggest that the detection of happy facial expressions is impaired in individuals with ASD and high ATs, which may contribute to their difficulty in creating and maintaining affiliative social relationships.

Atypical Modulations of N170 Component during Emotional Processing and Their Links to Social Behaviors in Ex-combatants

Emotional processing (EP) is crucial for the elaboration and implementation of adaptive social strategies. EP is also necessary for the expression of social cognition and behavior (SCB) patterns. It is well-known that war contexts induce socio-emotional atypical functioning, in particular for those who participate in combats. Thus, ex-combatants represent an ideal non-clinical population to explore EP modulation and to evaluate its relation with SCB. The aim of this study was to explore EP and its relation with SCB dimensions such as empathy, theory of mind and social skills in a sample of 50 subjects, of which 30 were ex-combatants from illegally armed groups in Colombia, and 20 controls without combat experience. We adapted an Emotional Recognition Task for faces and words and synchronized it with electroencephalographic recording. Ex-combatants presented with higher assertion skills and showed more pronounced brain responses to faces than Controls. They did not show the bias toward anger observed in control participants whereby the latter group was more likely to misclassify neutral faces as angry. However, ex-combatants showed an atypical word valence processing. That is, words with different emotions yielded no differences in N170 modulations. SCB variables were successfully predicted by neurocognitive variables. Our results suggest that in ex-combatants the links between EP and SCB functions are reorganized. This may reflect neurocognitive modulations associated to chronic exposure to war experiences.

Direction of Amygdala-Neocortex Interaction During Dynamic Facial Expression Processing

Dynamic facial expressions of emotion strongly elicit multifaceted emotional, perceptual, cognitive, and motor responses. Neuroimaging studies revealed that some subcortical (e.g., amygdala) and neocortical (e.g., superior temporal sulcus and inferior frontal gyrus) brain regions and their functional interaction were involved in processing dynamic facial expressions. However, the direction of the functional interaction between the amygdala and the neocortex remains unknown. To investigate this issue, we re-analyzed functional magnetic resonance imaging (fMRI) data from 2 studies and magnetoencephalography (MEG) data from 1 study. First, a psychophysiological interaction analysis of the fMRI data confirmed the functional interaction between the amygdala and neocortical regions. Then, dynamic causal modeling analysis was used to compare models with forward, backward, or bidirectional effective connectivity between the amygdala and neocortical networks in the fMRI and MEG data. The results consistently supported the model of effective connectivity from the amygdala to the neocortex. Further increasing time-window analysis of the MEG demonstrated that this model was valid after 200 ms from the stimulus onset. These data suggest that emotional processing in the amygdala rapidly modulates some neocortical processing, such as perception, recognition, and motor mimicry, when observing dynamic facial expressions of emotion.

Neuroticism Delays Detection of Facial Expressions

The rapid detection of emotional signals from facial expressions is fundamental for human social interaction. The personality factor of neuroticism modulates the processing of various types of emotional facial expressions; however, its effect on the detection of emotional facial expressions remains unclear. In this study, participants with high- and low-neuroticism scores performed a visual search task to detect normal expressions of anger and happiness, and their anti-expressions within a crowd of neutral expressions. Anti-expressions contained an amount of visual changes equivalent to those found in normal expressions compared to neutral expressions, but they were usually recognized as neutral expressions. Subjective emotional ratings in response to each facial expression stimulus were also obtained. Participants with high-neuroticism showed an overall delay in the detection of target facial expressions compared to participants with low-neuroticism. Additionally, the high-neuroticism group showed higher levels of arousal to facial expressions compared to the low-neuroticism group. These data suggest that neuroticism modulates the detection of emotional facial expressions in healthy participants; high levels of neuroticism delay overall detection of facial expressions and enhance emotional arousal in response to facial expressions.

Emotional attention capture by facial expressions

Previous studies have shown that emotional facial expressions capture visual attention. However, it has been unclear whether attentional modulation is attributable to their emotional significance or to their visual features. We investigated this issue using a spatial cueing paradigm in which non-predictive cues were peripherally presented before the target was presented in either the same (valid trial) or the opposite (invalid trial) location. The target was an open dot and the cues were photographs of normal emotional facial expressions of anger and happiness, their anti-expressions and neutral expressions. Anti-expressions contained the amount of visual changes equivalent to normal emotional expressions compared with neutral expressions, but they were usually perceived as emotionally neutral. The participants were asked to localize the target as soon as possible. After the cueing task, they evaluated their subjective emotional experiences to the cue stimuli. Compared with anti-expressions, the normal emotional expressions decreased and increased the reaction times (RTs) in the valid and invalid trials, respectively. Shorter RTs in the valid trials and longer RTs in the invalid trials were related to higher subjective arousal ratings. These results suggest that emotional facial expressions accelerate attentional engagement and prolong attentional disengagement due to their emotional significance.