Confirmation bias
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In psychology and cognitive science, confirmation bias (or confirmatory bias) is a tendency to search for or interpret information in a way that confirms one's preconceptions, leading to statistical errors. Confirmation bias is a type of cognitive bias and represents an error of inductive inference toward confirmation of the hypothesis under study.
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[edit] Overview
Confirmation bias is a phenomenon wherein decision makers have been shown to actively seek out and assign more weight to evidence that confirms their hypothesis, and ignore or underweigh evidence that could disconfirm their hypothesis. As such, it can be thought of as a form of selection bias in collecting evidence.
Among the first to investigate this phenomenon was Wason (1960), whose subjects were presented with three numbers (a triple):
| 2 | 4 | 6 |
and told that triple conforms to a particular rule. They were then asked to discover the rule by generating their own triples and use the feedback they received from the experimenter. Every time the subject generated a triple, the experimenter would indicate whether the triple conformed to the rule (right) or not (wrong). The subjects were told that once they were sure of the correctness of their hypothesized rule, they should announce the rule.
While the actual rule was simply “any ascending sequence”, the subjects seemed to have a great deal of difficulty in inducing it, often announcing rules that were far more complex than the correct rule. More interestingly, the subjects seemed to only test “positive” examples; that is, triples that subjects believed would conform to their rule and thus confirm their hypothesis. What the subjects did not do was attempt to falsify their hypotheses by testing triples that they believed would not conform to their rule. Wason referred to this phenomenon as the confirmation bias, whereby subjects systematically seek evidence to confirm rather than to deny their hypotheses.
The confirmation bias was Wason’s original explanation for the systematic errors made by subjects in the Wason selection task. In essence, the subjects were only choosing to examine cards that could confirm the given rule rather than disconfirm it. Confirmation bias has been used as a theory for why people believe and maintain pseudoscientific ideas.
[edit] Social phenomena
Some have argued that confirmation bias may be the cause of self-perpetuating and self-fulfilling social beliefs. This bias may occur at least partially because negatives are inherently more difficult to process mentally than positives [citation needed].
More recent studies, however, have shown that while confirmation bias tends to be present as an initial condition, the repeated presentation of disconfirmatory data induces changes in theoretical thinking. In other words, the initial disconfirmatory data are regarded as the result of error, or some other externally attributed factor; it is only after similar results or data are repeatedly obtained that a change in causal reasoning strategies occurs.
[edit] Political bias study
In January 2006, Drew Westen and a team from Emory University announced at the annual Society for Personality and Social Psychology conference in Palm Springs, California the results of a study showing the brain activity for confirmation bias. Their results suggest the unconscious and emotion driven nature of this form of bias.
The study was carried out during the pre-electoral period of the 2004 presidential election on 30 men, half who described themselves as strong Republicans and half as strong Democrats. During a functional magnetic resonance imaging (fMRI) scan the subjects were asked to assess contradictory statements by both George W. Bush and John Kerry. The scans showed that the part of the brain associated with reasoning, the dorsolateral prefrontal cortex, was not involved when assessing the statements. Conversely, the most active regions of the brain were those involved in processing emotions (orbitofrontal cortex), conflict resolution (anterior cingulate cortex) and making judgment about moral accountability (posterior cingulate cortex). [1]
Dr. Westen summarised the work: [2]
| None of the circuits involved in conscious reasoning were particularly engaged. Essentially, it appears as if partisans twirl the cognitive kaleidoscope until they get the conclusions they want, and then they get massively reinforced for it, with the elimination of negative emotional states and activation of positive ones... Everyone from executives and judges to scientists and politicians may reason to emotionally biased judgments when they have a vested interest in how to interpret 'the facts'. |
These data have not yet been published in a peer-reviewed scientific journal, but are currently under revision for publication. [3]
[edit] See also
[edit] References
- ^ Shermer, Michael (July 2006). The Political Brain. Scientific American. Retrieved on 2006-09-03.
- ^ Emory University Health Sciences Center (2006-01-31). Emory Study Lights Up The Political Brain. Science Daily. Retrieved on 2006-09-03.
- ^ Westen, Drew, Kilts, C., Blagov, P., Harenski, K., and Hamann, S. (2006). "The neural basis of motivated reasoning: An fMRI study of emotional constraints on political judgment during the U.S. Presidential election of 2004.". Journal of Cognitive Neuroscience..
- Wason, P.C. (1960). On the failure to eliminate hypotheses in a conceptual task. Quarterly Journal of Experimental Psychology, 12, 129-140.
- Wason, P.C. (1966). Reasoning. In B. M. Foss (Ed.), New horizons in psychology I, 135-151. Harmondsworth, UK: Penguin.
- Wason, P.C. (1968). Reasoning about a rule. Quarterly Journal of Experimental Psychology, 20, 273-281.
- Mynatt, C.R., Doherty, M.E., & Tweney, R.D. (1977). Confirmation bias in a simulated research environment: an experimental study of scientific inference. Quarterly Journal of Experimental Psychology, 29, 85-95.
- Griggs, R.A. & Cox, J.R. (1982). The elusive thematic materials effect in the Wason selection task. British Journal of Psychology, 73, 407-420.
- Nickerson, R.S. (1998). Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology, 2, 175-220.
- Fugelsang, J., Stein, C., Green, A., & Dunbar, K. (2004). Theory and data interactions of the scientific mind: Evidence from the molecular and the cognitive laboratory. Canadian Journal of Experimental Psychology, 58, 132-141.
