A reduced confidence gap e g Moritz et al

A reduced confidence gap (e.g., Moritz et al., 2003) in combination with an enhanced error rate may culminate in a state termed inflated “knowledge corruption” (i.e., the proportion of high confidence errors on all high confident responses). In other words, a high proportion of what the individual believes to be true is actually wrong. If individuals cannot distinguish between correct and incorrect subjective facts, momentous mistakes may happen, which may foster paranoid ideation (for a review see Moritz and Woodward, 2006c). In line with this, a recent study found a linear relationship between the level of subjective conviction for a (simulated) paranoid scenario, and emotional, as well as behavioral consequences, for example, arming oneself and being prepared to hurt someone when feeling threatened (Moritz and Van Quaquebeke, 2014). In our view, errors are not necessarily momentous if a false assumption is further tested and is not regarded as a definite truth. However, caution is warranted as some studies have not found cross-sectional associations between high confidence errors and delusional ideation (e.g., Moritz and Woodward, 2006c).
So far, most studies on overconfidence have employed memory or social cognition tests. Replication is needed for perceptual tasks. A multitude of investigations suggests that perceptual functions are compromised in the disorder (Chen, 2011; Silverstein and Keane, 2011; Tan et al., 2013; van Assche and Giersch, 2011; Yoon et al., 2013), including early visual processes (Knebel et al., 2011). One of the best replicated visual deficits pertains to smooth pursuit movements as well as other eye tracking dysfunctions (Levy et al., 2010; O\’Driscoll and Callahan, 2008), which recently has been linked with a failure to use efference copy information (Spering et al., 2013). As Javitt (2009) points out, impairments in basic perceptual processes may elicit higher order cognitive processing deficits. Hence, the study of visual, auditory and other perceptual aspects may help to reveal more about the origins of cognitive deficits in schizophrenia.
As of yet, it has not been studied whether errors in perceptual tasks are also accompanied by overconfident appraisals. In a recent investigation on a nonclinical order Sunitinib (Moritz et al., 2014), we assessed whether the liability to delusions would be associated with overconfidence in errors in a perceptual task (embedded figures task) that did not demand memory or social skills. Healthy individuals with high scores on core paranoid symptoms were overconfident in incorrect responses and demonstrated a significantly enhanced knowledge corruption index relative to subjects with lower scores (20% vs. 12%).
For the present study, we hypothesized that schizophrenia patients would display overconfidence in errors for perceptual judgments and would show an enhanced knowledge corruption relative to both healthy and psychiatric controls. We chose patients with obsessive–compulsive disorder as the psychiatric control group because of interesting similarities and differences to psychosis. While OCD has been sometimes dubbed “disorder of doubt”, as patients constantly worry about things Haversian canal usually know are unfounded and absurd, paranoia can be dubbed “disorder of conviction” as confidence in delusional beliefs is high per definitionem. At the same time, the demarcation is sometimes blurry as many OCD patients perceive their obsessions as partly perceptual (Moritz et al. 2014a) and a subgroup of OCD patients shows poor illness insight, which has been added to the DSM-V, recently.


Groups did not differ in age or gender (Table 1). Although healthy subjects showed a tendency towards higher education, group differences were insignificant on this variable. Schizophrenia patients made less hits (i.e., correct identification of an object, irrespective of confidence) and less overall correct responses (i.e., hits and correct rejections) relative to healthy controls but not compared with psychiatric controls (see Table 2). No group differences emerged for false alarms (i.e., object mistakenly perceived as present). Regarding metacognitive parameters, a number of schizophrenia-specific impairments were seen. Compared with OCD patients and healthy controls, individuals with psychosis showed a greater amount of high-confident errors on all errors, a greater frequency of high-confident incorrect responses and accordingly a higher knowledge corruption index (% of all high-confident errors on all high-confident responses; see Table 2). Relative to healthy controls but not schizophrenia participants, OCD participants showed a lower number of high-confident correct responses as well as a lower percentage of high-confident correct responses on all correct responses.