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Fmoc-Leu-OH manufacturer People with schizophrenia suffer a wide range of social cognitive

People with schizophrenia suffer a wide range of social cognitive deficits (for reviews, see Green and Horan, 2010; Green and Leitman, 2008), including disturbances in the processing of eye gaze. For instance, patients spend less time spontaneously scanning eye regions of other people’s faces compared to controls (Green and Phillips, 2004; Phillips and David, 1997) and have shown a bias to misjudge averted gaze as being direct (Hooker and Park, 2005; Rosse et al., 1994; Tso et al., 2012). Whether these abnormalities are a consequence of higher-order social–cognitive deficits, are driven by top-down beliefs about \”being watched\”, or, instead, are caused by a more fundamental low-level perceptual impairment is currently unknown.
The literature to date on disturbances in gaze perception in schizophrenia suggests that Fmoc-Leu-OH manufacturer the observed impairments may reflect a late stage of gaze processing, affecting the evaluation of eye gaze (Franck et al., 1998, 2002; Hooker and Park, 2005; Tso et al., 2012). For instance, the reported bias to misjudge averted gaze as direct appears task dependent. When patients are asked to make self-referential decisions about whether another person’s gaze is directed towards them or not (e.g., are the eyes looking at or away?), the direct gaze bias is reported (Hooker and Park, 2005; Rosse et al., 1994; Tso et al., 2012). However, when patients make simple direction judgments (e.g., are the eyes directed left or right?), the bias has not been reliably observed (Franck et al., 1998, 2002). These effects of task instruction raise questions about whether direct gaze bias in schizophrenia may result from either a self-referential decision bias or a higher-level impairment concerned with attributing intentional mental states to eye gaze (i.e., when asked is the person looking at you? – which is a probe about the other person’s intention), rather than an early perceptual processing deficit per se.
However, the data are far from conclusive with regard to ruling out an early impairment concerned with the encoding of gaze direction in schizophrenia. For instance, although Franck et al. (1998, 2002) found no evidence of direct gaze bias using a left/right judgment task that appeared to eliminate mental state attributions and self-referential processing, their studies also failed to detect any bias using the standard self-referential categorization task (Franck et al., 2002), suggesting that the results may be dependent on sample characteristics rather than task instructions. Also, Hooker and Park (2005) convincingly ruled out a generalized low-level perceptual deficit accounting for gaze disturbance in schizophrenia, but their study did not directly assess perceptual mechanisms specific to gaze perception (in the absence of self-referential judgments), which might be impaired in this group. Given that direct eye gaze can also signal threat (Emery, 2000) and patients with schizophrenia show a hypersensitivity to threat signals (Bentall and Kaney, 1989; Blackwood et al., 2001; Fear et al., 1996), there is theoretical impetus to comprehensively investigate early detection of direct gaze signals in schizophrenia.
Research to date using task instructions that require either self-referential decisions or left/right gaze discrimination judgments has only considered one aspect of gaze perception; the ability to consciously differentiate gaze deviations. Thus, it remains unknown whether or not patients show abnormalities in the simple detection of eye gaze direction. In particular, do they show evidence of the rapid preferential detection of direct eye contact (Brothers, 1990; Conty et al., 2006; Driver et al., 1999; Senju & Hasegawa, 2005; Stein et al., 2011; von Grunau and Anston, 1995; Yokoyama et al., 2011)? This is a question that cannot be addressed measuring gaze discrimination thresholds.
To directly test whether disturbances in gaze processing in schizophrenia originate at an early detection stage of gaze processing, it is necessary to employ methods that (a) do not require a discriminative judgment about gaze direction and (b) tap preconscious stages of gaze processing where eye contact is first registered in the visual system. Thus, in this study we use a technique known as continuous flash suppression (CFS; Tsuchiya and Koch, 2005) to probe unconscious mechanisms leading to rapid detection of eye-contact. The CFS paradigm involves suppressing a target stimulus from conscious awareness for an extended period of time. Potency of the target to break into awareness, as measured with simple detection response times, is considered an index of unconscious processing (Tsuchiya et al., 2009). It has been shown in healthy individuals that target faces with direct eye gaze break into awareness earlier (and are thus detected earlier) than target faces with averted gaze (Stein et al., 2011; Yokoyama et al., 2013), indicating preferential and distinct processing of direct eye contact that is early, is automatic, and occurs in the absence of conscious awareness.