چهره پردازی معکوس در اختلال بدریخت انگاری

Individuals with body dysmorphic disorder (BDD) are preoccupied with perceived defects in appearance. Preliminary evidence suggests abnormalities in global and local visual information processing. The objective of this study was to compare global and local processing in BDD subjects and healthy controls by testing the face inversion effect, in which inverted (upside–down) faces are recognized more slowly and less accurately relative to upright faces. Eighteen medication-free subjects with BDD and 17 matched, healthy controls performed a recognition task with sets of upright and inverted faces on a computer screen that were either presented for short duration (500 ms) or long duration (5000 ms). Response time and accuracy rates were analyzed using linear and logistic mixed effects models, respectively. Results indicated that the inversion effect for response time was smaller in BDD subjects than controls during the long duration stimuli, but was not significantly different during the short duration stimuli. Inversion effect on accuracy rates did not differ significantly between groups during either of the two durations. Lesser inversion effect in BDD subjects may be due to greater detail-oriented and piecemeal processing for long duration stimuli. Similar results between groups for short duration stimuli suggest that they may be normally engaging configural and holistic processing for brief presentations. Abnormal visual information processing in BDD may contribute to distorted perception of appearance; this may not be limited to their own faces, but to others’ faces as well.

Body Dysmorphic Disorder (BDD) is a psychiatric disorder in which individuals are preoccupied with an imagined defect of appearance or are excessively concerned about a slight physical abnormality, which causes distress and/or functional impairment (American Psychiatric Association, 2000). BDD affects approximately 1–2% of the population (Faravelli et al., 1997, Koran et al., 2008, Otto et al., 2001 and Rief et al., 2006), and is associated with high lifetime rates of psychiatric hospitalization (48%) (Phillips and Diaz, 1997a) and suicide attempts (22–27.5%) (Phillips et al., 2005, Phillips and Diaz, 1997a, Phillips and Menard, 2006 and Veale et al., 1996). Previous studies estimate that 27–60% are delusional in their beliefs (Mancuso et al., 2010 and Phillips, 2004). Individuals with BDD tend to engage in repetitive and compulsive behaviors such as checking their appearance in the mirror and scrutinizing details of others’ appearances to compare to their own (Phillips, 2005). Despite the prevalence and severity of the disorder, relatively little is known about the pathophysiology underlying various symptom domains. Clinical observation and neuropsychological data suggest that abnormal information processing may underscore the apparent perceptual abnormalities in BDD. Clinically, they often focus on details of their appearance, frequently involving their faces, at the expense of global or configural aspects. A neuropsychological study using the Rey–Osterrieth Complex Figure Test demonstrated that BDD patients performed poorly relative to controls due to differences in organizational strategies including selective recall of details instead of larger organizational design features (Deckersbach et al., 2000). Individuals with BDD may also have abnormalities in own-face processing, as evidenced by a study in which they perceived distortions that were not actually present (Yaryura-Tobias et al., 2002). Moreover, studies by Buhlmann et al., 2004 and Buhlmann et al., 2006 found abnormalities in emotional face processing in BDD consisting of recognition biases and/or misinterpretation of faces that were perceived as contemptuous or otherwise negative (Buhlmann et al., 2006 and Buhlmann et al., 2004). Whether these recognition biases or misinterpretations are the result of abnormalities in visual processing is not clear. In general, face processing is an important function of the brain, underscored by how critical it is for social functioning. Efficient face processing relies both on featural and configural information (Moscovitch et al., 1997). Featural information about faces includes details such as skin smoothness, blemishes, lines, hair texture, etc. and is conveyed by high spatial frequency information (Norman and Ehrlich, 1987 and Schyns and Oliva, 1999). Configural information includes basic spatial relationships of features (e.g. eyes above the mouth), distances between features, and holistic elements (i.e. the face as one percept) (Maurer et al., 2002) and is conveyed by low spatial frequency information (Costen et al., 1996 and Sergent, 1985). At short viewing durations lower spatial frequencies are primarily processed (Breitmeyer, 1975 and Breitmeyer and Ganz, 1977), as they occur on a faster timescale than processing of high spatial frequencies (Peyrin et al., 2006 and Schyns and Oliva, 1994). In addition, no more than two eye fixations typically occur for exposure durations of 500 ms or less, while detail processing is serial in nature and requires multiple eye fixations and therefore longer viewing times (Castelhano et al., 2009 and Hsiao and Cottrell, 2008). In healthy adults, viewing inverted faces impairs recognition, which is believed to be the result of disrupted configural processing. Yin (1969) first reported that inversion of faces, but not objects, disrupted behavioral performance on a recognition task (Yin, 1969). This “face inversion effect” is defined as the difference in performance between upright and inverted photographs of faces (Farah et al., 1995, Leder and Bruce, 2000 and Valentine, 1988). This most likely occurs because the presence of a general structure or uniform set of features allows for a configural template for efficient processing of different faces, although variations exist between individual faces (Freire et al., 2000). However, this template does not apply when faces are inverted; individuals may then have to rely more on the faces’ component parts. The face inversion effect is eliminated in healthy controls when they are forced to learn the faces in terms of their component parts and then asked to recognize them when inverted (Farah et al., 1995). This supports the idea that the face inversion effect is dependent on holistic processing of upright images. Another study demonstrated that, given longer exposure to the stimuli, subjects experienced an increased ability to recognize inverted faces (Barton et al., 2001). This suggests that configural, or global, processing provides an advantage over component, or local, processing only given stimuli with shorter presentation times, and that longer times may allow for part decomposition.