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Judgement (Tversky & Kahneman (Conjunction Fallacy (PPs given…
Judgement
Tversky & Kahneman
Conjunction Fallacy
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85% ranked bank teller and feminist (h) to be more likely than just bank teller (f)
But h = X + Y, f = X -> so h must be less likely
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Gave pps a simplified version of the study containing only options h & f - Still 85% made the conjunction fallacy
Misinterpretation? - Linda is bank teller and not a feminist - if this is the case, judgements may be correct
Changed the statement - reduced CF to 57%
Heuristic = Quick procedures that frequently find the correct solution (not guaranteed) - Cognitive shortcuts, rules of thumb
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^^ “Linda is a bank teller and is active in the feminist movement” is more representative of the ‘kind of person’ Linda seems to be.
PPs in International Congress on Forecasting - 2 groups evaluated the probability of statements a & b (about Russia)
b more probable than a - Even experts make Conjunction Fallacies
Availability Heuristic
2000 random words from book, start with 'r' or has 'r' as its third letter - most pps said starts with 'r' as they are easier to bring to mind
The easier it is to bring an event to mind, the more likely that event is judged to be
Frequentist Approach
People have evolved to think in terms of frequencies (e.g. out of 10 times) rather than single event probabilities (e.g. 10% chance)
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Performance of some tasks improves when problems are phrased in terms of frequencies rather than single event probabilities
Cosmides & Tooby
Rephrased Cascell's Q in terms of frequencies - Input information changed from %'s to frequencies, Q changed from single-event prob to freq judgement
Fiedler
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100 women fit a certain description, how many work at a bank and how many work at a bank and are feminists
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Clark & Teasdale
Positive and negative memories recalled more in the appropriate mood (depression) - therefore, words and associations change their availability
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Casscells
Medical staff given medical related question - 50% estimated the probability at 95% = Base Rate Neglect
Range of Heuristics: Representativeness, Availability,
End Anchoring