Atypical trait inferences from facial cues in alexithymia

On the Relationship Between Alexithymia and Social Cognition: A Systematic Review

Objective

This systematic review summarises the studies that have investigated the relationship between dimensions of social cognition (i.e., Theory of Mind - ToM, emotion recognition, and empathy) and alexithymia in the general adult non-clinical population.

Method

PubMed, PsycINFO, and Scopus databases were screened, using the following strings: ("alexithymi*") AND ("theory of mind" OR "ToM"); ("alexithymi*") AND ("empath*"); ("alexithymi*") AND ("emotion recognition"); ("alexithymi*") AND ("social cognition").

Results

A total of 117 studies met the inclusion criteria and were included in this review. The total number of participants included in the reviewed studies was 40,231. Mixed results were found for alexithymia and ToM, while the relationship between emotion recognition or empathy and alexithymia was more homogeneous. Alexithymia was found to be significantly associated with both a reduced ability to recognise emotions and empathy.

Conclusions

These results support the existence of significant relationships between alexithymia and altered social cognitive abilities. Future research is needed to confirm the present findings and further elucidate the complex relationship between these processes. Suggestions are made on how to overcome some of the theoretical and methodological problems in the literature.

Alexithymia modulates emotion concept activation during facial expression processing

Alexithymia is characterized by difficulties in emotional information processing. However, the underlying reasons for emotional processing deficits in alexithymia are not fully understood. The present study aimed to investigate the mechanism underlying emotional deficits in alexithymia. Using the Toronto Alexithymia Scale-20, we recruited college students with high alexithymia (n = 24) or low alexithymia (n = 24) in this study. Participants judged the emotional consistency of facial expressions and contextual sentences while recording their event-related potentials. Behaviorally, the high alexithymia group showed longer response times versus the low alexithymia group in processing facial expressions. The event-related potential results showed that the high alexithymia group had more negative-going N400 amplitudes compared with the low alexithymia group in the incongruent condition. More negative N400 amplitudes are also associated with slower responses to facial expressions. Furthermore, machine learning analyses based on N400 amplitudes could distinguish the high alexithymia group from the low alexithymia group in the incongruent condition. Overall, these findings suggest worse facial emotion perception for the high alexithymia group, potentially due to difficulty in spontaneously activating emotion concepts. Our findings have important implications for the affective science and clinical intervention of alexithymia-related affective disorders.

Why is the literature on first impressions so focused on White faces?

We spontaneously attribute to strangers a wide variety of character traits based on their facial appearance. While these first impressions have little or no basis in reality, they exert a strong influence over our behaviour. Cognitive scientists have revealed a great deal about first impressions from faces including their factor structure, the cues on which they are based, the neurocognitive mechanisms responsible, and their developmental trajectory. In this field, authors frequently strive to remove as much ethnic variability from stimulus sets as possible. Typically, this convention means that participants are asked to judge the likely traits of White faces only. In the present article, we consider four possible reasons for the lack of facial diversity in this literature and find that it is unjustified. Next, we illustrate how the focus on White faces has undermined scientific efforts to understand first impressions from faces and argue that it reinforces socially regressive ideas about 'race' and status. We go on to articulate our concern that opportunities may be lost to leverage the knowledge derived from the study of first impressions against the dire consequences of prejudice and discrimination. Finally, we highlight some promising developments in the field.

Visual attention mechanisms in happiness versus trustworthiness processing of facial expressions

A happy facial expression makes a person look (more) trustworthy. Do perceptions of happiness and trustworthiness rely on the same face regions and visual attention processes? In an eye-tracking study, eye movements and fixations were recorded while participants judged the un/happiness or the un/trustworthiness of dynamic facial expressions in which the eyes and/or the mouth unfolded from neutral to happy or vice versa. A smiling mouth and happy eyes enhanced perceived happiness and trustworthiness similarly, with a greater contribution of the smile relative to the eyes. This comparable judgement output for happiness and trustworthiness was reached through shared as well as distinct attentional mechanisms: (a) entry times and (b) initial fixation thresholds for each face region were equivalent for both judgements, thereby revealing the same attentional orienting in happiness and trustworthiness processing. However, (c) greater and (d) longer fixation density for the mouth region in the happiness task, and for the eye region in the trustworthiness task, demonstrated different selective attentional engagement. Relatedly, (e) mean fixation duration across face regions was longer in the trustworthiness task, thus showing increased attentional intensity or processing effort.

Facial attractiveness impressions precede trustworthiness inferences: lower detection thresholds and faster decision latencies

Prior research has found a relationship between perceived facial attractiveness and perceived personal trustworthiness. We examined the time course of attractiveness relative to trustworthiness evaluation of emotional and neutral faces. This served to explore whether attractiveness might be used as an easily accessible cue and a quick shortcut for judging trustworthiness. Detection thresholds and judgment latencies as a function of expressive intensity were measured. Significant correlations between attractiveness and trustworthiness consistently held for six emotional expressions at four intensities, and neutral faces. Importantly, perceived attractiveness preceded perceived trustworthiness, with lower detection thresholds and shorter decision latencies. This reveals a time course advantage for attractiveness, and suggests that earlier attractiveness impressions could bias trustworthiness inferences. A heuristic cognitive mechanism is hypothesised to ease processing demands by relying on simple and observable clues (attractiveness) as a substitute for more complex and not easily accessible information (trustworthiness).

Modulation of the composite face effect by unintended emotion cues

When upper and lower regions from different emotionless faces are aligned to form a facial composite, observers 'fuse' the two halves together, perceptually. The illusory distortion induced by task-irrelevant ('distractor') halves hinders participants' judgements about task-relevant ('target') halves. This composite-face effect reveals a tendency to integrate feature information from disparate regions of intact upright faces, consistent with theories of holistic face processing. However, observers frequently perceive emotion in ostensibly neutral faces, contrary to the intentions of experimenters. This study sought to determine whether this 'perceived emotion' influences the composite-face effect. In our first experiment, we confirmed that the composite effect grows stronger as the strength of distractor emotion increased. Critically, effects of distractor emotion were induced by weak emotion intensities, and were incidental insofar as emotion cues hindered image matching, not emotion labelling per se. In Experiment 2, we found a correlation between the presence of perceived emotion in a set of ostensibly neutral distractor regions sourced from commonly used face databases, and the strength of illusory distortion they induced. In Experiment 3, participants completed a sequential matching composite task in which half of the distractor regions were rated high and low for perceived emotion, respectively. Significantly stronger composite effects were induced by the high-emotion distractor halves. These convergent results suggest that perceived emotion increases the strength of the composite-face effect induced by supposedly emotionless faces. These findings have important implications for the study of holistic face processing in typical and atypical populations.