User:Sophpsych/sandbox

= Facial Signals of Personality =

One’s appearance is commonly used to form social judgements of others. Due to appearance based judgments being so prominent in everyday judgments and interactions, research has tested the accuracy and correlations between facial appearance and behaviours. Studies provide conflicting results, with some researchers arguing face-based social judgements merely bias our choices and decisions, whereas other research has suggested that facial appearance contains a kernel of truth about the individual’s traits and behaviours. Preconceived judgments based on facial appearance alone is shown to bias political election outcomes, decision making and outweigh inferences made by written factual information of an individual’s nature. However, individuals have been found to accurately perceive personality of others just from a static expressionless photo of their face indicating ‘judging a book by its cover’ is not necessarily a social bias that should be avoided and rather the face is a valid tool for social judgements.

= Evidence for Facial Signals of Personality =

Personality ratings from a static face
Alongside signals of emotion, research has indicated that the face signals personality traits. Even in the absence of emotional expression, static neutral faces provide accurate information about stable traits of personality. Using composite expressionless photos of multiple individuals scoring high or low on specific personality traits of the Big Five, individuals are able to accurately judge the personality of strangers from their facial appearance alone. In addition to levels of openness, contentiousness, extraversion, agreeableness and neuroticism, accurate detection of social and behavioural traits including that of trustworthiness, dominance, aggression, intelligence and health are also shown to be involuntarily signalled via one’s facial morphology. Furthermore, research has found that personality can be detected from photos of individual non-composite faces with significant accuracy found for ratings of extraversion. Specific fixation of personality signals on the face is shown by greater accuracy in ratings from facial signals as opposed to other parts of the body. Agreeableness is better identified from facial appearance that the more extensive attribute of gait. These findings suggest that not only do humans signal personality and internal attributes from their facial appearance, but humans also obtain the ability to read these facial signals from others.

Holistic Vs Internal facial features
The accuracy of personality detection differs when based on composite images of a whole face or based on the more limited presentation of internal facial stimuli (cropped composite faces showing only the eyes nose and mouth). Correct detection of personality has been found for four of the Big Five personality traits (openness, extraversion, agreeableness and neuroticism) when based on internal facial features alone. Accurate personality detection was not found for contentiousness and physical health suggesting these domains require more holistic facial appearance in order to be detected by others. However, external facial features seem to be important in the detection of facial signals of extraversion and physical health with improved accuracy found from the full-face images (in comparison to internal faces). This research suggests that facial signals of specific attributes obtain different morphology or facial locations.

Facial width to height ratio (fWHR)
Facial width to height ratio, the ratio of the bizygomatic-width to upper face height is a sexually dimorphic trait, with a larger fWHR found in males. Individual differences in fWHR has previously been used as a measurement and predictor of aggression, with high fWHR being found to positively correlate to aggressive behaviour both in laboratory behavioural tasks and real life settings, FWHR in males has been associated with achievement drive, untrustworthiness and unethical behaviour such as deception. Males with greater facial width not only were more likely to exploit the trust of others but were also less likely to be trusted by their peers compared to males with more narrow faces. Also, narrow-faced males are more likely to die from direct contact violence than wider-faced males, perhaps due to lower levels of dominance. Research examining facial width of the Chief Executive Officers (CEOs) of leading UK businesses found that dominance and success was correlated to each individuals fWHR, with strangers correctly rating the CEO’s as more dominant and successful than photographs of non CEO’s. However, research into fWHR is conflicting, with other studies finding no correlation between fWHR of males and reported levels of aggression. In addition, facial width to height ratio being gender specific is questionable with comparable fWHR found between males and females

= Trustworthiness =

Facial Morphology
It is still unclear what specific facial features influence or equate to specific signals of personality traits. However, research into trust evaluation has suggested specific face shape and structures that link to a face that signals either high or low levels of trust. Kleisner, Priplatova, Frost & Flegr (2013) found a correlation between an individual’s eye colour and their appearance of trustworthiness, with individuals with brown eyes perceived to be more trustworthy than those whom have blue eyes. However, when the eye colour on the facial stimuli was reversed the same results were found suggesting that it is the facial shape and structure related to individuals with brown eyes rather than the specific eye colour that influences perceived trustworthiness. Geometric morphometric correlates suggest that the facial structure mostly associated with brown eyes is commonly perceived as more trustworthy. Individuals with brown eyes tend to have a rounder and broader chin, a broader mouth with upward-pointing corners, relatively bigger eyes, and eyebrows closer to each other, features that are commonly allocated to a trustworthy face during trust evaluation studies. Whereas, blue eyed individuals commonly display a more prominent angular lower face, a longer chin, a more narrow mouth with downward pointing corners, relatively smaller eyes, and further apart eyebrows, synonymous of untrustworthy rated faces.

Neurological responses to Trust signals
The activity of the amygdala, one of the brain regions involved in decision making and evaluation of emotions, is sensitive to facial signals of trustworthiness playing a role in implicit evaluations of trustworthiness of faces. Responses by the amygdala are automatic with amygdala activity in response to untrustworthy faces elicited even when participants were not actively judging levels of trust. Face-trait inferences occur spontaneously and remarkably rapidly, within as little as 33ms. Impromtu and rapid judgements of personality detection via facial signals is further suggested by exposure time not having an effect on accuracy of judgement. Under a longer exposure of 500 ms and thus a longer time available to create a decision, personality judgments are made just as rapidly if not quicker, when exposed to a face for a shorted time of 100 ms. Research using functional magnetic resonance imaging has found greater neural activation in the bilateral amygdala and right insula, and also the right superior temporal sulcus, in response to untrustworthy faces during a trust discrimination task. The amygdala response towards untrustworthy facial signals was found to increase as the perceived trustworthiness of faces decreases. The role of the amygdala in face processing is also shown by research involving brain damaged participants. Impaired judgment of untrustworthiness from faces was found in individuals with bilateral amygdala damage, rating previously agreed untrustworthy and negatively attributed faces more positively than neuro-typical controls.

Evolved Social Signalling System
Automatic and enhanced activation of the amygdala towards socially dangerous facial stimuli, be it untrustworthy faces or expressions of fear, is suggested to be the result of an adaptive response to potentially dangerous stimuli. Instant responses towards threatening facial signals of others may have evolved to serve the purpose of protection against deception assisting social judgements of another’s intent. One suggestion by the field of evolutionary research is that such abilities to detect personality and facial signals are the product of an evolved social signalling system of which may serve the adaptive function of inferring harmful intentions of others, in turn providing protection against deception. If such an evolved social signalling system exists it would be expected that we would share personality structure and facial morphology with that of our closest evolved relative the chimpanzee. Humans are indeed able to detect facial signals of extraversion and dominance not only in individuals of our own species, but also that of our close relation, the chimpanzee. A shared personality structure between that of humans and chimpanzees is suggested by the cross-generalisation of personality traits between species alongside similarities of facial morphology that are apparent within human and chimpanzee facial muscular structure and facial expression further providing evidence for the existence of an evolved social signalling system. In addition an innate ability to detect facial personality signals is suggested by a typical ability to infer social attributes from the faces of others by individuals with prosopagnosia. Despite impaired holistic face recognition individuals with prosopagnosia seem to still be able to detect subtle facial cues of personality.

= Evaluation =

The validity and diagnostic ability of facial evaluations and detection of facial signals is controversial. Research by Olivia & Torodov (2010) analysed over 1 million appearance-based judgements and concluded that using appearances and facial cues overall had a detrimental effect on their ability to predict another’s intentions and characteristics. Rather predicting characteristics of others would be more accurate if individuals based their decisions solely on knowledge of basic information inferring characteristics, e.g textual explanation of their personality and previous behaviours. It is therefore suggested that more research into facial cues is needed in order to determine which cues help or hinder accurate social judgments. The ability to detect personality from facial signals and cues has been criticised for being merely caused by the reading of lower-level featural dimensions. Stable, expressionless photos of individuals may still obtain subtle emotional expressions which are then used to infer characteristics and intent. A neutral face containing structural overlaps to the emotional expressions, for example of anger or joy, contribute to the perceived level of trustworthiness. Therefore it may be the complex arrangements of these low- level facial features that form the overall differences in the facial appearance of trust.

= References=