확증 편향(Confirmation bias) : 어떤 것이 옳다고 믿는 신념을 더 강화하려는 우리의 행동패턴.

(출처 : http://allsquareinc.blogspot.kr/2006/05/confirmation-bias.html)

잠깐 실험을 하나 해 보겠습니다. 위에 네 장의 카드가 있습니다. 한 쪽에는 숫자가 써있고, 반대 쪽에는 알파벳이 쓰여 있습니다. 다음 문장이 틀렸음을 증명하려면 어떤 카드를 뒤집어야 할까요? 

"한 면에 모음이 있다면, 반대 면에는 짝수가 있다"

Here's a little test: Pictured to the right are four cards. Each card contains a letter on one side, and a number on the other. Which cards must you turn over to prove the following statement false? "If a card has a vowel on one side, then it has an even number on the other side."


Peter Wason과 Philip Johnson-Laird는 비슷한 128명에게 비슷한 실험을 하였고, 가장 흔한 대답은 "A와 4입니다" 였다. 두 번째로 흔한 대답은 "A만 뒤집어보면 된다" 였다.  "A와 9" 라는 옳은 답을 말한 사람은 5%에 불과했다.

Researchers Peter Wason and Philip Johnson-Laird gave a similar test to 128 college-educated subjects in 1972. The most frequently given answer was "A and 4," (46 percent), with "only A" the second most popular (33 percent). Only 5 percent gave the correct answer, which is "A and 9."


A를 뒤집어보면 된다는 것은 쉽게 이해가 된다. 그런데 많은 사람들은 4 카드를 뒤집어서 뒷면에 모음이 있어야 하는지를 봐야 한다고 응답했다. 그러나 그것은 위의 명제가 틀렸음을 증명하는데 아무런 도움이 되지 않는다.
It's fairly obvious that you must turn over the A-card: if there is an odd number on the other side of the card, you have proven the statement false. The popular tendency is to also turn over the 4-card to see if there is a vowel on the other side. However, the statement does not say an even-numbered card cannot have a consonant. For the same reason, turning over the S-card proves nothing, since the statement makes no claims about cards with consonants. On the other hand, turning over the 9-card and finding a vowel proves the statement false.


왜 이 문제를 틀린 사람이 그렇게 많을까? 정답은 흔히 일어나는 논리적 행위인 ""확증 편향"이라는 것 때문이다. 대부분의 사람은 어떤 것이 '틀렸음'을 증명하는 것보다 어떤 것을 '옳았음'을 증명하는 것을 선호한다. 따라서 위의 문제를 보면, 해야 하는 일이 '틀렸음'을 증명하는 것임에도(9를 뒤집어서), 기존에 가지고 있던 신념이 '옳았음'을 증명하고 싶어지는 것이다(4를 뒤집어서). 

이러한 과정에서 우리는 잘못된 가정을 세우게 되는 것이다.
Why does this test fool so many people? The answer is a common act of reasoning called confirmation bias. Research shows that most people prefer confirming something rather than proving something wrong. Therefore, we gravitate toward confirming our beliefs--even when our task is to disprove something. (By turning over the 4-card we're trying to find further confirmation of the statement.) In the process, we make some flawed assumptions. 

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(출처 : http://online.wsj.com/article/SB10001424052748703811604574533680037778184.html)

확증 편향(Confirmation bias)

자신의 신념이나 가설에 들어맞는 정보를 선호하는 경향성

Confirmation bias (also called confirmatory bias or myside bias) is a tendency of people to favor information that confirms their beliefs or hypotheses.^{[Note 1][1]} 

People display this bias when they gather or remember information selectively, or when they interpret it in a biased way. 

The effect is stronger for emotionally charged issues and for deeply entrenched beliefs. 

For example, in reading about gun control, people usually prefer sources that affirm their existing attitudes. 

They also tend to interpret ambiguous evidence as supporting their existing position. 

Biased search, interpretation and memory have been invoked to explain attitude polarization (when a disagreement becomes more extreme even though the different parties are exposed to the same evidence), belief perseverance (when beliefs persist after the evidence for them is shown to be false), the irrational primacy effect (a greater reliance on information encountered early in a series) and illusory correlation (when people falsely perceive an association between two events or situations).

A series of experiments in the 1960s suggested that people are biased toward confirming their existing beliefs. 

Later work re-interpreted these results as a tendency to test ideas in a one-sided way, focusing on one possibility and ignoring alternatives. In certain situations, this tendency can bias people's conclusions. 

두 가지 해석 : Wishful thinking, 틀릴 것에 대한 비용을 높여 계산함.

Explanations for the observed biases include wishful thinking and the limited human capacity to process information. 

Another explanation is that people show confirmation bias because they are weighing up the costs of being wrong, rather than investigating in a neutral, scientific way.

신념에 대한 자신감을 높여줘서 그 믿음을 유지시키거나 더 강하게 만듬

Confirmation biases contribute to overconfidence in personal beliefs and can maintain or strengthen beliefs in the face of contrary evidence. Poor decisions due to these biases have been found in military, political, and organizational contexts.

(출처 : http://en.wikipedia.org/wiki/Confirmation_bias)