In developing a hypothesis, it may be appropriate to seek confirming data, but in testing it’s important also to look for disconfirming evidence. Most of the instances of confirmation bias examined below involve testing. Q. What is danger of hearing an estimate from even a source we deem reliable? [anchoring] Why are people overconfident? Availability: We pay attention to strength, or extremeness, of evidence vs. its weight. Strength — size of the effect Weight — significance or reliability (sample size or base rate) We recruit evidence that favors our hypothesis. We anchor on strength and adjust (insufficiently) for its weight. The vividness of particular impressions trumps our knowledge of base rates. After interviewing individuals, participants were asked to predict whether, given the choice, the interviewees would take a free subscription to Playboy or The New York Review of Books. Even when told that 68% of all the people interviewed preferred Playboy, participants tended to ignore this base rate and premise their predictions on their own impressions from the interviews. They were only correct 50% of the time, but 72% were certain that their predictions were accurate. People are generally overconfident about general-knowledge items of moderate or extreme difficulty, such as many of the trivia questions. While knowledgeable subjects responding to easy questions tend to be underconfident, also a deviation from good calibration. With the possible exception of authoritarian personalities, individual differences don’t correlate with overconfidence. seem to Overconfidence Dyad Exercise Slides (Slides 174-178) Confirmation Biases: Barriers to Revision (Slide 179) You can use any trivial pursuit–type item to be estimated—though some students will inevitably say that they had superior knowledge to their partner. Collect the dyads’ differences. In the two classes I’ve taught this, there is some movement toward the mean in the first part, more movement toward the mean in the second part, but still divergence. The best strategy in conditions of ignorance is to adopt the mean of the two estimates. Many students resist this, but putting them in the position of an observer helps. Naive Realism Slides (Slides 180-187) Debiasing Slides (Slides 188-189) Slides 190-191: Beliefs about climate change, Open carry problem
In developing a hypothesis, it may be appropriate to seek confirming data, but in testing it’s important also to look for disconfirming evidence. Most of the instances of confirmation bias examined below involve testing. Q. What is danger of hearing an estimate from even a source we deem reliable? [anchoring] Why are people overconfident? Availability: We pay attention to strength, or extremeness, of evidence vs. its weight. Strength — size of the effect Weight — significance or reliability (sample size or base rate) We recruit evidence that favors our hypothesis. We anchor on strength and adjust (insufficiently) for its weight. The vividness of particular impressions trumps our knowledge of base rates. After interviewing individuals, participants were asked to predict whether, given the choice, the interviewees would take a free subscription to Playboy or The New York Review of Books. Even when told that 68% of all the people interviewed preferred Playboy, participants tended to ignore this base rate and premise their predictions on their own impressions from the interviews. They were only correct 50% of the time, but 72% were certain that their predictions were accurate. People are generally overconfident about general-knowledge items of moderate or extreme difficulty, such as many of the trivia questions. While knowledgeable subjects responding to easy questions tend to be underconfident, also a deviation from good calibration. With the possible exception of authoritarian personalities, individual differences don’t seem to correlate with overconfidence. Overconfidence Dyad Exercise Slides (Slides 174-178) Confirmation Biases: Barriers to Revision (Slide 179) You can use any trivial pursuit–type item to be estimated—though some students will inevitably say that they had superior knowledge to their partner. Collect the dyads’ differences. In the two classes I’ve taught this, there is some movement toward the mean in the first part, more movement toward the mean in the second part, but still divergence. The best strategy in conditions of ignorance is to adopt the mean of the two estimates. Many students resist this, but putting them in the position of an observer helps. Naive Realism Slides (Slides 180-187) Debiasing Slides (Slides 188-189) Slides 190-191: Beliefs about climate change, Open carry problem
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