Overconfidence in psychosis: The foundation of delusional conviction?

Figures & data

Table 1. Knowledge corruption across overconfidence studies

Studies	Knowledge corruption (%)^1			Effect size (d)
	Schizophrenia		Healthy controls (HC)
Moritz and Woodward (2002)	11.8*		4.9	0.72
Moritz et al. (2004)	33.7**		21.2	1.01
Moritz et al. (2005)	20.9**		8.6	0.77
Moritz and Woodward (2006a)	21.9***		12.6	0.87
Moritz, Woodward, and Chen (2006)	20.9***		9.4	1.45
Moritz, Woodward, and Rodriguez-Raecke (2006)	24.2**		18.3	0.71
Moritz et al. (2008)	23.4***		6.2	0.92
Gawęda et al. (2012)	40.7***		22.7	1.24
Peters et al. (2013)	17.8**		8.4	1.27
Moritz, Ramdani, et al. (2014)	17.2***		6.5	0.86
Bhatt et al. (2010)	Experiencing delusions (ED)	Not experiencing delusions (ND)		ED vs. HC	ND vs. HC
Total knowledge corruption	46.2**	45.5**	28.9	1.37	1.03
False-positive knowledge corruption	57.2	47.9	43.6	0.72	0.20
False-negative knowledge corruption	18.0**	12.0	5.2	1.22	0.68
	High-delusion-proneness/paranoia		Low -delusion-proneness/paranoia
Laws and Bhatt (2005)^2	46***		27	1.20
Moritz, Göritz, et al. (2014)^3	20.1***		11.9	0.63
Moritz et al. (2015)^3	11.23***		3.76	0.52

¹ Knowledge corruption is the proportion of high-confidence errors on all high-confidence responses.

² Delusion-proneness determined by Peters et al. Delusions Inventory within healthy controls.

³ Paranoia determined by the Paranoia Checklist within healthy controls; non-metamemory task.

^* p < .05.

^** p < .01.

^*** p < .001.

Moritz, S., & Woodward, T. S. (2002). Memory confidence and false memories in schizophrenia. The Journal of Nervous and Mental Disease, 190, 641–643.

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Moritz, S., Woodward, T. S., Cuttler, C., Whitman, J. C., & Watson, J. M. (2004). False memories in schizophrenia. Neuropsychology, 18, 276–283.

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Moritz, S., Woodward, T. S., Whitman, J., & Cuttler, C. (2005). Confidence in errors as a possible basis for delusions in schizophrenia. The Journal of Nervous and Mental Disease, 193, 9–16.

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Moritz, S., & Woodward, T. S. (2006a). The contribution of metamemory deficits to schizophrenia. Journal of Abnormal Psychology, 115, 15–25.

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Moritz, S., Woodward, T. S., & Chen, E. Y. H. (2006). Investigation of metamemory dysfunctions in first-episode schizophrenia. Schizophrenia Research, 81, 247–252.

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Moritz, S., Woodward, T. S., & Rodriguez-Raecke, R. (2006). Patients with schizophrenia do not produce more false memories than controls but are more confident in them. Psychological Medicine, 36, 659–667.

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Moritz, S., Woodward, T. S., Jelinek, L., & Klinge, R. (2008). Memory and metamemory in schizophrenia: A liberal acceptance account of psychosis. Psychological Medicine, 38, 825–832.

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Gawęda, Ł., Moritz, S., & Kokoszka, A. (2012). Impaired discrimination between imagined and performed actions in schizophrenia. Psychiatry Research, 195, 1–8.

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Peters, M. J. V., Hauschildt, M., Moritz, S., & Jelinek, L. (2013). Impact of emotionality on memory and meta-memory in schizophrenia using video sequences. Journal of Behavior Therapy and Experimental Psychiatry, 44, 77–83.

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Moritz, S., Ramdani, N., Klass, H., Andreou, C., Jungclaussen, D., Eifler, S., … Zink, M. (2014). Overconfidence in incorrect perceptual judgments in patients with schizophrenia. Schizophrenia Research: Cognition, 1, 165–170.

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Bhatt, R., Laws, K. R., & McKenna, P. J. (2010). False memory in schizophrenia patients with and without delusions. Psychiatry Research, 178, 260–265.

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Laws, K. R., & Bhatt, R. (2005). False memories and delusional ideation in normal healthy subjects. Personality and Individual Differences, 39, 775–781.

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Moritz, S., Göritz, A. S., Van Quaquebeke, N., Andreou, C., Jungclaussen, D., & Peters, M. J. V. (2014). Knowledge corruption for visual perception in individuals high on paranoia. Psychiatry Research, 215, 700–705.

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Moritz, S., Göritz, A. S., Gallinat, J., Schafschetzy, M., Van Quaquebeke, N., … Andreou, C. (2015). Subjective competence breeds overconfidence in errors in psychosis. A hubris account of paranoia. Journal of Behavior Therapy and Experimental Psychiatry, 48, 118–124.

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