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Face Perception in Individuals Diagnosed with Autism Spectrum Disorder

 * Autism Spectrum Disorder (ASD) is a comprehensive neural developmental disorder that produces many deficits including social, communicative, and perceptual deficits . Of specific interest, individuals with autism exhibit difficulties in various aspects of facial perception, including facial identity recognition and recognition of emotional expressions. These deficits are suspected to be a product of abnormalities occurring in both the early and late stages of facial processing.

Methods of Facial Processing

 * Abnormalities in ASD face processing are expressed as equivalent processing speeds of face and non-face stimuli. In typically developing individuals, there is a preference for face processing, thus resulting in a faster processing speed in comparison to non-face stimuli. Typically developing individuals primarily utilize holistic processing when perceiving faces. Contrastingly, individuals with ASD employ part-based processing or bottom-up processing, focusing on individual features rather than the face as a whole.  When focusing on the individual parts of the face, persons with ASD direct their gaze primarily to the lower half of the face, specifically the mouth, varying from the eye trained gaze of typically developing people.    This deviation from holistic face processing does not employ the use of facial prototypes, which are templates stored in memory that make for easy retrieval. Additionally, individuals with ASD display difficulty with recognition memory, specifically memory that aids in identifying faces. The memory deficit is selective for faces and does not extend to other objects or visual inputs. Some evidence lends support to the theory that these face-memory deficits are products of interference between connections of face processing regions.

Causes of Abnormal Facial Processing

 * The atypical facial processing style of ASD persons often manifests in constrained social ability, due to decreased eye contact, joint attention, interpretation of emotional expression, and communicative skills. These deficiencies can be seen in infants as young as 9 months; specifically in terms of poor eye contact and difficulties engaging in joint attention. Some experts have even used the term 'face avoidance' to describe the phenomena where infants who are later diagnosed with ASD preferentially attend to non-face objects over faces. Furthermore, some have proposed that the demonstrated impairment in children with ASD's ability to grasp emotional content of faces is not a reflection of the incapacity to process emotional information, but rather, the result of a general inattentiveness to facial expression. The constraints of these processes that are essential to the development of communicative and social-cognitive abilities are viewed to be the cause of impaired social engagement and responsivity. Furthermore, research suggests that there exists a link between decreased face processing abilities in individuals with ASD and later deficits in Theory of Mind; for example, while typically developing individuals are able to relate others' emotional expressions to their actions, individuals with ASD do not demonstrate this skill to the same extent. There is some contention about this causation, resembling the chicken or the egg dispute. Others theorize that social impairment leads to perceptual problems rather than vice versa. In this perspective, a biological lack of social interest inherent to ASD inhibits developments of facial recognition and perception processes due to underutilization. Continued research is necessary to determine which theory is best supported.

Neurology of Atypical Facial Processing

 * Many of the obstacles that individuals with ASD face in terms of facial processing may be derived from abnormalities in the fusiform gyrus and amygdala, which have been shown to be important in face perception as discussed above. Typically, the fusifrom gryus in individuals with ASD has reduced volume compared to normally developed persons. This volume reduction has been attributed to deviant amygdala activity that does not flag faces as emotionally salient and thus decreases activation levels of the fusiform gyrus. This hypoactivity can also be seen in neuroimaging studies. When looking at faces, persons with ASD exhibit activity in brain regions normally active when typically developing individuals perceive objects. [[file: autism and FG.jpeg | thumb | This functional MRI scan shows how individuals with ASD exhibit activity outside the [[fusiform face area|fusiform gyrus]] during facial perception, unlike typically developing individuals. ]] These findings are on trend with current research that uses neuroimaging as the main mechanism for understanding the ASD brain and it’s manner of facial perception.

Compensation Mechanisms

 * As ASD individuals age, scores on behavioral tests assessing ability to perform face-emotion recognition increase to levels similar to controls. Yet, it is apparent that the recognition mechanisms of these individuals are still atypical, though often effective. In terms of face identity-recognition, compensation can take many forms including a more pattern-based strategy which was first seen in face inversion tasks (see face inversion section within global precedence). Alternatively, evidence suggests that older individuals compensate by using mimicry of other’s facial expressions and rely on their motor feedback of facial muscles for face emotion-recognition. These strategies help overcome the obstacles individuals with ASD face in interacting within social contexts.