Skip to main content Accessibility help

Confirmation bias: why psychiatrists stick to wrong preliminary diagnoses

  • R. Mendel (a1), E. Traut-Mattausch (a2), E. Jonas (a3), S. Leucht (a1), J. M. Kane (a4), K. Maino (a5), W. Kissling (a1) and J. Hamann (a1)...



Diagnostic errors can have tremendous consequences because they can result in a fatal chain of wrong decisions. Experts assume that physicians' desire to confirm a preliminary diagnosis while failing to seek contradictory evidence is an important reason for wrong diagnoses. This tendency is called ‘confirmation bias’.


To study whether psychiatrists and medical students are prone to confirmation bias and whether confirmation bias leads to poor diagnostic accuracy in psychiatry, we presented an experimental decision task to 75 psychiatrists and 75 medical students.


A total of 13% of psychiatrists and 25% of students showed confirmation bias when searching for new information after having made a preliminary diagnosis. Participants conducting a confirmatory information search were significantly less likely to make the correct diagnosis compared to participants searching in a disconfirmatory or balanced way [multiple logistic regression: odds ratio (OR) 7.3, 95% confidence interval (CI) 2.53–21.22, p<0.001; OR 3.2, 95% CI 1.23–8.56, p=0.02]. Psychiatrists conducting a confirmatory search made a wrong diagnosis in 70% of the cases compared to 27% or 47% for a disconfirmatory or balanced information search (students: 63, 26 and 27%). Participants choosing the wrong diagnosis also prescribed different treatment options compared with participants choosing the correct diagnosis.


Confirmatory information search harbors the risk of wrong diagnostic decisions. Psychiatrists should be aware of confirmation bias and instructed in techniques to reduce bias.


Corresponding author

*Address for correspondence: PD Dr S. Leucht, Department of Psychiatry, Technische Universität München, Ismaninger Straße 22, 81675 München, Germany. (Email:


Hide All
Arkes, HR (1981). Impediments to accurate clinical judgment and possible ways to minimize their impact. Journal of Consulting and Clinical Psychology 49, 323330.
Arocha, JF, Patel, VL, Patel, YC (1993). Hypothesis generation and the coordination of theory and evidence in novice diagnostic reasoning. Medical Decision Making 13, 198211.
Ask, K, Granhag, PA (2007). Motivational bias in criminal investigators' judgments of witness reliability. Journal of Applied Psychology 37, 561591.
Berner, ES (2007). Clinical Decision Support Systems: Theory and Practice. Springer-Verlag: New York.
Berner, ES, Maisiak, RS, Cobbs, CG, Taunton, OD (1999). Effects of a decision support system on physicians' diagnostic performance. Journal of the American Medical Informatics Association 6, 420427.
Crichton, M (2007). Where does it hurt? New York Times ( Accessed 14 May 2009.
Croskerry, P (2002). Achieving quality in clinical decision making: cognitive strategies and detection of bias. Academic Emergency Medicine 9, 11841204.
Croskerry, P (2003 a). The importance of cognitive errors in diagnosis and strategies to minimize them. Academic Medicine 78, 775780.
Croskerry, P (2003 b). Cognitive forcing strategies in clinical decision making. Annals of Emergency Medicine 41, 110120.
Dawson, NV (2000). Physician judgments of uncertainty. In Decision Making in Health Care: Theory, Psychology, and Applications (ed. Chapman, G. B. and Sonnenberg, F. A.), pp. 211252. Cambridge University Press: New York.
Elstein, AS, Schwartz, A (2002). Clinical problem solving and diagnostic decision making: selective review of the cognitive literature. British Medical Journal 324, 729732.
Festinger, L (1964). Conflict, Decision, and Dissonance. Stanford University Press: Stanford, CA.
Fischer, P, Jonas, E, Frey, D, Schulz-Hardt, S (2005). Selective exposure to information: the impact of information limits. European Journal of Social Psychology 35, 469492.
Frey, D (1981). Informationssuche und Informationsbewertung bei Entscheidungen [Information Seeking and Information Evaluation in Decision Making]. Verlag Hans Huber: Bern.
Frey, D (1986). Recent research on selective exposure to information. In Advances in Experimental Social Psychology (ed. Berkowitz, L.), pp. 4180. Academic Press: New York.
Friedman, MH, Connell, KJ, Olthoff, AJ, Sinacore, JM, Bordage, G (1998). Medical student errors in making a diagnosis. Academic Medicine 73 (Suppl. 10), S19S21.
Gallagher, EJ (2003). Thinking about thinking. Annals of Emergency Medicine 41, 121122.
Gambrill, E (2005). Critical Thinking in Clinical Practice: Improving the Quality of Judgements and Decisions. John Wiley & Sons Inc.: Hoboken, NJ.
Graber, MA, VanScoy, D (2003). How well does decision support software perform in the emergency department? Emergency Medicine Journal 20, 426428.
Groopman, JE (2007). How Doctors Think. Houghton Mifflin Publishing Co: Boston, MA.
Gurmankin, AD, Baron, J, Hershey, JC, Ubel, PA (2002). The role of physicians' recommendations in medical treatment decisions. Medical Decision Making 22, 262271.
Hirt, ER, Markman, KD (1995). Multiple explanation: a consider-an-alternative strategy for debiasing judgments. Journal of Personality and Social Psychology 69, 10691086.
Jonas, E, Frey, D (2003). Information search and presentation in advisor-client interaction. Organizational Behavior and Human Decision Processes 91, 154168.
Jonas, E, Schulz-Hardt, S, Frey, D, Thelen, N (2001). Confirmation bias in sequential information search after preliminary decisions: an expansion of dissonance theoretical research on selective exposure to information. Journal of Personality and Social Psychology 80, 557571.
Kern, L, Doherty, ME (1982). ‘Pseudodiagnosticity’ in an idealized medical problem-solving environment. Journal of Medical Education 57, 100104.
Klayman, J (1995). Varieties of confirmation bias. Psychology of Learning and Motivation 32, 358418.
Klein, JG (2005). Five pitfalls in decisions about diagnosis and prescribing. British Medical Journal 330, 781783.
Krems, JF, Zierer, C (1994). Are experts immune to cognitive bias? Dependence of ‘confirmation bias’ on specialist knowledge [in German]. Zeitschrift für experimentelle und angewandte Psychologie 41, 98–115.
Mynatt, CR, Doherty, ME, Tweney, RD (1978). Consequences of confirmation and disconfirmation in a simulated research environment. Quarterly Journal of Experimental Psychology 30, 395406.
Nemeth, CJ, Connell, JB, Rogers, JD, Brown, KS (2001). Improving decision making by means of dissent. Journal of Applied Social Psychology 31, 4858.
Newman-Toker, DE, Pronovost, PJ (2009). Diagnostic errors – the next frontier for patients safety. Journal of the American Medical Association 301, 10601062.
Nickerson, RS (1998). Confirmation bias: a ubiquitous phenomenon in many guises. Review of General Psychology 2, 175220.
Parmley, MC (2006). The effects of the confirmation bias on diagnostic decision making ( Accessed 14 May 2009.
Pines, JM (2006). Profiles in patient safety: confirmation bias in emergency medicine. Academic Emergency Medicine 13, 9094.
Ramnarayan, P, Cronje, N, Brown, R, Negus, R, Coode, B, Moss, P, Hassan, T, Hamer, W, Britto, J (2007). Validation of a diagnostic reminder system in emergency medicine: a multi-centre study. Emergency Medicine Journal 24, 619624.
Weingart, SN, McL Wilson, R, Gibberd, RW, Harrison, B (2000). Epidemiology of medical error. Western Journal of Medicine 172, 390393.
Wolf, FM, Gruppen, LD, Billim, JE (1985). Differential diagnosis and the competing-hypotheses heuristic. A practical approach to judgment under uncertainty and Bayesian probability. Journal of the American Medical Association 253, 28582862.
Wolf, FM, Gruppen, LD, Billi, JE (1988). Use of the competing-hypotheses heuristic to reduce ‘pseudodiagnosticity’. Journal of Medical Education 63, 548554.


Related content

Powered by UNSILO

Confirmation bias: why psychiatrists stick to wrong preliminary diagnoses

  • R. Mendel (a1), E. Traut-Mattausch (a2), E. Jonas (a3), S. Leucht (a1), J. M. Kane (a4), K. Maino (a5), W. Kissling (a1) and J. Hamann (a1)...


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.