PSYCH 240 Lecture Notes - Lecture 19: Representativeness Heuristic, Birth Order, Deductive Reasoning
Document Summary
Ex. ground is wet, infer that it rained . could have been a street cleaner that rolled through though. Ex. client reports hearing voices . evidence points to schizophrenia. But you also have to consider base rate (inductive reasoning) Base rate: probability of the hypothesis not looking at the evidence! Ex. if schizophrenia was super rare then the probability that the patient has schizo is not that high. Normative inductive reasoning: base rate and current evidence. Mammogram example: doctors confuse p(h/e) and p(e/h). Probabilistic inductive reasoning (normative b/c it"s the right way to do it, inductive b/c the conclusions aren"t guaranteed to be true/they aren"t deductively valid) Bayes theorem--understand the 3 pieces of information you need to determine. Normative: uses baye"s theorem, which takes base rate into consideration: people are non normative though and put too much weight on evidence rather than base rate. Descriptive theory: attempts to explain errors not just correct behavior. Why do we do this? b/c of heuristics.
