The Representative Heuristic PDF

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The Representative Heuristic...

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The Representative Heuristic -Judging the likelihood that a particular instance comes from a particular category of things or events based on how representative it is of that category -representativeness (or similarity) of the instance is independent of the prior probability (or base rate) of the category -idea/theory used to explain what we can see -Dick no more representative of engineer then lawyer, so 50:50. Conjunction fallacy -Linda is 31 years old, single, outspoken and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in antinuclear demonstrations. -What is the probability that Linda is: -a bank teller? 1 condition to be true -a bank teller and is active in the feminist movement? 2 conditions to be true -‘What is the probability of A being the case?’ versus ‘What is the probability of A AND B being the case?’ -I condition more likely to be true because less conditions to be meet, this isn’t found to be the case -Possible explanation: conjunctions of features make an instance more representative of the category, at the same time as it reduces the ‘objective’ probability How common is something? How likely is a particular event? (The Availability Heuristic) =judgments of frequency and likelihood based on how readily instances or occurrences can be brought to mind -Seems sensible in absence of certain, perfect knowledge, but systematic biases due to -imaginability =how easy is it to imagine a scenario? -retrievability =how easy is it to retrieve relevant instances? -For example, apparent tendency for people to overestimate the likelihood of some negative events (and underestimate the likelihood of others) therefore, think of them as more risky. Availability and sex (Brown and Sinclair, 1999) -When asked to judge , men estimate they’ve had 2-4 times more (opposite) sexual partners than do women, should be roughly the same -lots of judgments based on asking people e.g. number of units drink a week -don’t know whether they are telling the truth or not -Heuristics (strategies for making the judgment) -Enumeration= people went through their memory counting them up -Keeping a tally -Rough guess

-women are more likely to do enumeration and to keep a tally -men more likely to do rough guesstimate -when used rough approximation you come up with a higher number then if do enumeration -judgments we make vary depending on what strategies we use Summary -Appropriate judgements have to be based on evidence -People seem to deal with evidence in a way that leads to biases -Base rate neglect -Conjunction fallacy -Over- and under-estimation of frequencies of events -Suggestion that people don’t weigh up evidence, but rather use heuristics to make judgements -representativeness -availability -These seem to lead to irrational behaviour (or at least they seem to distort judgments) -i.e., judgments aren’t based on sound appraisal of all available evidence...