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PSYCH291 Chapter Notes -Illusory Correlation, Rorschach Test

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John Holmes

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The Tendency to Try to Explain Chance Events
Characteristic of human intelligence to search for structure & conceptual understanding
Called a chance event b/c no easy way to measure all variables (at least, not currently)
Explain Chance: Illusory Correlation and the Illusion of Control
Illusory correlation = ppl tend to see their expected corr’l even in random events; they see structure where
there is none
i.e. psych practitioners cont’ to believe in efficacy of Rorschach test
Illusion of control = tendency to believe tht personal skill can affect outcomes dtrmn’d by chance
Chance and Psychology
Before accepting complicated explanation of an event, consider what part chance may have played in its
Occurrence of related events due to chance
dN need explanation
Oddmatch = 2 events whose co-occurrence strikes us as odd/strange; occur purely b/c of chance
Laws of probability guarantee as # of events i↑’s, probability of oddmatch occurring becomes very high
- guarantees them in long run
Accepting Errors in Order to Reduce Error: Clinical vs. Actuarial Prediction
Reluctance to acknowledge role of chance when trying to explain outcomes in world can actually dour
ability to predict real-world events
- we must accept error in order to reduce error
Actuarial prediction = predictions based on group trends derived from statistical records
i.e. ppl who are obese in middle age 4X more likely than nonobese to have heart problem after age 65
Clinical/case prediction = subgroups of clinical psych practitioners claim to be able to go beyond group
predictions and make accurate predictions of outcomes of particular indvdls
Actuarial prediction > clinical prediction b/c AP eq’n integrates info accurately and consistently (main
adv of AP over CP: actuarial eq’n is public knowledgeopen for all to use/modify/criticize/dispute
- in contrast, CP amnts to reliance on an authority whose assessments not subject to public criticism
yet, embarrassingly, psych field dN act on this knowledge
i.e. cont’s to use personal interviews even though evidence suggests they have no valiidty