The late positive potential (LPP) is an event-related potential (ERP) component associated with increased affective processing which seems to strongly respond to threats and to be sensitive to emotional faces. Some studies indicate that the LPP is modulated by anxiety symptoms, while others fail to find support for these observations. The facial width-to-height ratio (FWHR) is a facial-masculinity metric that refers to cheekbone width, divided by upper facial height (top of the lip to between the brows). Consequently, FWHR has by some researchers been proposed to serve as a cue of threat. For example, high FWHR and diverse emotional faces (e.g., angry faces) are perceived as more threatening than low FWHR faces. Individuals with social anxiety are thought to be biased towards the threat. The literature has indicated that high FWHR faces in combination with angry facial expression can elicit larger LPPs compared to low FWHR and neutral faces. The current experiment investigated subjective ratings in addition to the LPP in response to high and low FWHR faces in combination with an angry and neutral expression, to examine how different facial morphology and affective cues influence the perception of threat to individuals with high social anxiety. This data, in combination, suggests that high FWHR is a salient threat-related social stimulus that might have a firm influence on the perception of other peoples’ faces. Initial results do not support a significant relationship between increased LPP modulation in individuals with high social anxiety compared to individuals with low social anxiety. However, it opens up for discussion regarding how social anxiety should be approached in future LPP research.

Previous studies support that the relative width of the upper face (facial width-to-height ratio; fWHR) has evolved to signal threat, but these studies rely greatly on subjective facial ratings and measurements prone to confounds. The present study objectively quantifies threat perception to the magnitude of the observers’ electrophysiological reaction, specifically the event-related potential (ERP) called the late positive potential (LPP), and investigate if brow height and jaw width could have confounded previous fWHR studies. Swedish and international students (N = 30, females = 11, Mage = 24 years, SDage = 2.9) were shown computer-generated neutral faces created with the underlying skeletal morphology varying in brow ridge height, cheekbone width and jaw width. Participants first rated how threatening each face was and then viewed 12 blocks of 64 faces while their electroencephalography (EEG) was recorded. The results supported that the LPP could be used to index threat perception and showed that only brow height significantly affected both facial ratings (p < .001, ɳp2 = .698) and magnitude of the LPP within the 400 to 800 ms latency (p = .02, d = .542). Hence, brow height, not facial width, could explain previous findings. The results contradict the hypothesis that fWHR is an evolved cue of threat and instead support the overgeneralisation hypothesis in that faces with similar features to anger will be perceived as more threatening.

The late positive potential (LPP) is an event-related potential (ERP) component associated with increased affective processing. Studies have shown that stimuli with high evolutionary significance (e.g. a threatening face) induce increased activity over centro-parietal areas of the brain. In an electrophysiological context, this is hypothesized to be indexed by greater LPP amplitudes. The facial width-to-height ratio (fWHR) is a facial-masculinity metric which refers to cheekbone width, divided by upper facial height (top of the lip to between the brows). For the first time, LPP amplitudes were examined in subjects upon observing faces with high vs. low facial fWHRs. Prior studies suggest that faces with high fWHRs are perceived as more threatening than faces with low fWHRs. Consequently, fWHR has by some researchers been proposed to serve as a cue of threat. Two separate tasks in the present study were used to investigate this. In the aggression task, males with high fWHRs were judged as more aggressive. Moreover, when put in a threatening context, high fWHR faces also elicited greater LPP amplitudes in subjects compared to faces with low fWHRs. Conversely, in the self-regulation task, differences in LPP amplitudes did not reach significance. In this task, statistical power was low due to few blocks/trials in the ERP experiment and subjects were not primed on threat, which may explain the non-significant results. Taken together, the results provide modest support to the theory that fWHR serve as a cue of threat. Future studies will need to take the present study’s limitations into consideration

Existing evidence shows people are able to attribute an individual's behavioural characteristics based on their facial features with a certain level of accuracy; one such characteristic is the perception of physical strength in potential opponents within the male intersexual competition. Physical strength seems be assessed upon the level of masculine facial features development. However, attributions may be influenced by other factors - namely personality traits of the evaluator or the so-called Other-race effect. In this study portrait photographs of men from Europe and Africa were rated by a group of European evaluators on a perceived physical strength. The aim of this study was to assess the link between attributed physical strength, actual physical strength (grip strength) and facial morphology described by relative facial width (fWHR) the Index of Masculinity (potential effects of age, body weight and height on said variables were controlled for). The use of stimuli of different ethnic origin enabled us to test the accuracy of physical strength attributions and actual physical strength in context to the Other-race effect hypothesis. According to its wording people tend to attribute characteristics with higher accuracy to individuals, who belong to the same population, or with whom they are...

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