Tuesday, January 29, 2013

What is Congruence Bias?

By Philip Copitch, Ph.D.

Dear Dr. Phil,

I am taking AP Psychology and I am stumped when it comes to Congruence Bias. My teacher has explained it a few times and, I have talked it over with my classmates, but I am now more confused. Can you help?


Great Question Gerald,

It makes sense that this is hard to get a hold on. I often find that congruence bias even stumps researchers who are running experiments and publishing in their chosen fields.

Simply put, congruence bias occurs when a person accepts an answer without testing other hypotheses. 

People do this all the time and usually it has no ill effect. Let’s say you phone a friend and he doesn’t pick up. You probably assume he’s not home and decide to call him again later. In this story, you chose to assume that your first and only hypothesis is correct (friend not home) but, maybe you dialed the number incorrectly, or maybe he is eating dinner.

In the story above, there’s no real problem, but what if the police are called to a murder scene. All evidence points to the husband. So the police put out an all points bulletin to find the husband. Three days later, the husband is found, dead. He was slowly tortured to death by the real murderer. Because the police only looked for the husband, not testing other hypotheses (theories), they spent three days looking for the wrong person.

Sometimes in science, researchers are so sure that their hypothesis is correct that they do not test other hypotheses to truly understand what is going on. 

An example: 

In drug rehab research it was a common belief that high school students that  use marijuana are more likely to move onto harder drugs like heroin and methamphetamine. This mistaken idea came from surveying drug addicts and asking them what their first drug was. Many reported that they started with pot. On the surface this makes sense. But the survey question was flawed. It did not look at other things that could have been the gateway to hard drugs. Just because hard drug users reported pot in their past, the researchers stopped looking for other causes (Congruence Bias). The assumption was, pot came first, and pot was a nasty hippie young person drug, thus it must have caused the hard drug use. It was statistically sound, a large percent of heroin users reported it. But it was incorrect. 

Almost 100% of heroin drug users ate carrots when they were children. But we don’t think that carrots cause heroin use. Carrots do not "feel" like a good answer, so it would not fall into the experimenters cognitive bias. Remember, bias is prejudice for or against something. The problem is that often this prejudice is not recognized by the researcher.

Later research found that the gateway drug to hard drugs is cigarettes. It seems that the “screw you” attitude of teen smoking is a better indicator of future hard drug use.

So, to avoid congruence bias, I highly recommend asking ourselves, "How can I do/look/think about this differently?"

Thanks for the fun question. Be well,

Dr. Phil

Congruence Bias also called: hypothesis locking, myside bias, and the Tolstoy syndrome (Tolstoy liked to use this bias in his writings).

Further reading: 

Wason, P. C. (1960). On the failure to eliminate hypotheses in a conceptual task. Quarterly Journal of Experimental Psychology, 12, 129-140.
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, 557-571.

1 comment:

  1. Quite interesting and nice topic chosen for the post Nice Post keep it up.Excellent post.I want to thank you for this informative post. I really appreciate sharing this great post. Keep up your work.
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