Involuntary responses to facial cues as an indicator of personality type across age and culture

Can we learn something about the personality of a person we first encounter just by looking at their face and do we do this automatically and implicitly? Previous research by Jones et al (2019) has determined that accurate implicit personality trait judgements can be made from faces. However, it remains unclear what the mechanisms that underpin this process might be, and the degree to which they overlap with other face perception processes such as identity recognition and emotional expression processing. The present thesis aimed to investigate using individual differences approach, whether positively regarded traits among the Big-Five such as extraversion, agreeableness; and negatively regarded trait such as neuroticism judgements can be predicted accurately and implicitly using female young adult composite facial stimuli (Caucasian). It was also investigated whether the ageing process has a detrimental effect on accurate implicit personality judgements by testing a group of younger adults, and a group of older adults. Additionally, extraversion trait judgements among Developmental prosopagnosia and other-ethnicity samples were measured. Furthermore, the present thesis also sought to identify whether implicit trait judgement abilities could be driven by other cognitive factors such as autism traits, alexithymia traits, face memory and emotion perception. Specifically, whether self-perception of neuroticism predicted implicit neuroticism performances. The main findings of this thesis revealed that young adult Caucasian groups were able to form accurate implicit face-based trait judgements of extraversion and neuroticism. A similar pattern of performance was not observed for agreeableness trait judgements. Individuals with Developmental Prosopagnosia were able to form accurate implicit extraversion trait judgements. Older adult groups were able to make accurate implicit judgements of neuroticism, but this pattern was not the same for extraversion. Similarly, other-ethnicity groups did not demonstrate accurate judgements for extraversion. Throughout the empirical studies, the ability to from accurate implicit extraversion, neuroticism and agreeableness personality judgements were unrelated to other cognitive factors such as autism traits, alexithymia traits, face memory and emotion perception. Self-perception of neuroticism was also unrelated to implicit neuroticism trait judgements. On the basis of this pattern of findings, we conclude that face-based implicit trait judgements utilise some independent cognitive process to other face processing abilities, and that the interpretation of particular personality traits is differentially impacted by the ageing process. Based on the findings of this thesis, it is recommended for future research to examine other-ethnicity effects (non-Caucasian stimuli) and age effects (older facial stimuli) on implicit face-trait judgements in conjunction with the neural regions responsible for face-trait judgements (specifically the big-five) using neuroimaging methods.