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.