Atypical face scanning in ASC

Although the section reviewed above highlights atypical and attenuated preferences for social stimuli, some studies have demonstrated that ASC individuals do attend (under certain conditions) to social stimuli such as faces. Although findings are non-equivocal, a large number of studies suggest that when ASC individuals do look at faces, they do so in an atypical manner (Boraston & Blakemore, 2007). Typically, when people view faces, there is a bias towards

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fixating on the eye region and then on other core facial features such as the nose and mouth, a region known as the “face triangle” (Luria & Strauss, 1978). This orientation of visual attention towards the eyes is argued to have evolutionary (the detection of another’s eye gaze can provide threat cues) and social (eye contact mediates social interactions) value (Baron-Cohen, 1995; Kleinke, 1986). Furthermore, Batki et al. (2000) found that even neonates at just a few hours old, showed a preference for looking at pictures of faces with eyes open as opposed to eyes closed and Walker-Smith, Gale and Findlay (1977) found that normative visual scan paths that arise when adults look at faces, lean heavily towards fixations on the core facial features (eyes, nose and mouth), with two thirds of these fixations being directed towards the eye region.

In contrast, have yielded results suggesting that there is a tendency for ASC individuals to focus less on the eye region of the face (Dalton et al., 2005; Klin et al., 2002b; Langdell, 1978; Pelphrey et al., 2002;) and more on the mouth and lower face regions (Klin et al., 2002b; Langdell, 1978; Spezio et al., 2007). Langdell (1978) was one of first researchers to investigate atypical face processing in ASC. In a study into face identity recognition, Langdell observed that young ASC children were less adept at recognising the identity of a familiar face when they were presented with the upper regions of the face only (such as the eyes) compared to typically developing matched controls. However, when identifying faces from the lower regions of the face, ASC children were superior to controls, suggestive of differential face processing strategies. The more recent adoption of eye tracking technology has allowed researchers to more accurately uncover the strategies used when appraising faces in ASC and offer support to Langdell’s (1978) finding. For example, Pelphrey et al. (2002) observed that ASC adults attended less to the core facial features of static emotionally expressive face images (including the eyes, nose and mouth) and more to the non-core facial regions. This finding was replicated with ASC children in Riby and Hancock’s (2008) study, highlighting that ASC children looked less at the face and eye region of a static photograph relative to verbal and non-verbal matched non-ASC controls. Furthermore, in the Klin et al. (2002) study described above, ASC adolescents and adults were found to fixate twice as long on the mouth region and half as long on the eye region than did matched non-ASC controls. Klin et al. (2002) concluded that ASC individuals rely more heavily on the mouth region in order to come to a decision about emotions communicated facially at the expense of the more normative eye region. Klin et al.’s (2002)

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appraise social scenes. The stimuli used (video clips of social interactions) offered some degree of ecological validity and participants were not explicitly directed to attend to the faces in the social scene. Other studies using static stimuli (photographs of faces) and tasks which explicitly demand that participants attend to the face have also found attenuated eye region fixations in ASC (Dalton et al., 2005; Pelphrey et al., 2002; Spezio et al., 2007). For example, Gross (2004) observed that ASC children used the lower regions of the face when judging emotional expressions and, whereas FER performance in non-ASC controls was facilitated by the presentation of the whole face (rather than isolated regions only), ASC individuals demonstrated no further gains.

Furthermore, Spezio et al. (2007) observed atypical featural fixations to the eye and mouth regions and an enhanced propensity to saccade away from the eye region for emotionally expressive static faces. Using a bubbles paradigm which allowed the researchers to limit the amount of face information available, they tracked the eye movements of participants during a task which involved making a judgement as to whether a face was showing a happy or fearful emotional expression. Results highlighted that although HF ASC adults were as accurate as and as fast as age matched non-ASC controls in making simplistic emotion judgements, they fixated less on the eye region and made fixations to the mouth even when information from the eyes would have aided their emotion judgement. Spezio et al. (2007) observed that the high incidence of saccades away from the eye area was associated with task-specific information being present in the eyes. This finding appears to support the empathy imbalance hypothesis since it suggests that ASC individuals avert their gaze away from the eyes especially when emotive information is present. In addition to behavioural observations of eye gaze aversion, Gernsbacher and Frymiare (2005) reported a number of examples of ASC individuals reporting that eye contact is painful for them because they are emotionally significant. In support of anecdotal reports of discomfort from eye contact, Kylliananen and Hietanen (2006) provided psychophysiological evidence that ASC individuals actively avoid eye contact with other people as a way to decrease empathic arousal. Finally, according to Dalton et al. (2005), “face- processing deficits in autism arise from hyper activation in the central circuitry of emotion that produces heightened sensitivity to social stimuli” (p. 524). Such reluctance to appraise the eyes of others offer an explanation for face and emotional processing difficulties in ASC.

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As will be discussed later, the eye region (both the eyes and the eye brows) is particularly important in the communication of fear (Dimberg & Petterson, 2000) whereas other emotions (e.g. happiness) can be recognised from the mouth alone (Ekman & Friesen, 2003). Since ASC individuals are found to recognise happiness relatively easily (Baron-Cohen et al., 2000; Rump

et al., 2009) whilst fear is problematic (Boraston & Blakemore, 2007; Pelphrey et al., 2002), eye region aversion appears a plausible explanation for this phenomenon. Furthermore, non-ASC patients with amygdala lesions demonstrated both attenuated fixations to the eye region and difficulties recognising fearful facially expressed emotions (Adolphs et al., 2005) reaffirming the link between atypical amygdala functioning and face processing which has obvious implications for ASC populations who also present with atypical amygdala activation (Baron-Cohen et al., 2000) and atypical face processing abilities (in particular the recognition of fear).