Inductive reasoning problems … … … … ?? ?? 1210 Need to break out of mental set

A little experiment… You are given the cards below and asked to test the following hypothesis All cards with a vowel on one side have an even number on their opposite side What would be the first card you would check? Which would be the second card you would check? AJ47

AJ47 EVEN  CONSISTENT ODD  INCONSISTENT EVEN  INDETERMINATE ODD  INDETERMINATE VOWEL  INDETERMINATE CONSONANT  INDETERMINATE VOWEL  INCONSISTENT CONSONANT  CONSISTENT Confirmation Bias

Let’s try it again BeerCoke2216 You are given the cards below and asked to test the following hypothesis –If a person is drinking beer, she must be over age 19 What cards do you need to check? Do results just depend on artificiality of lab tests?

Why the difference? abstract vs. concrete situations? evolutionary perspective (Cosmides & Tooby, 1992) –people do better at four-card problems that involve cheating true for primitive cultures as well –people are good at detecting cheaters –detecting cheaters was evolutionarily important and may have become hard-wired in the brain

Estimating Probabilities Which is more prevalent, words that begin with the letter r, or words in which r is the third letter? Availability Bias 70% say there are more words starting with r Actually there are 3X as many words with r as the third letter than the first letter Why does this error occur?

Estimating Probabilities Are you more likely to die from: –homicide or appendicitis? –auto-train collision or drowning? –measles or smallpox? –botulism or asthma? –asthma or tornado? –pregnancy or appendicitis?

Availability Bias

deaths from car crashes outnumber homicide by 5:1 alcohol accounts for 40% of fatal car accidents failure to use seatbelts accounts for 1/3 of deaths people in 20s and 30s are most at risk, followed by seniors Jane Creba murdered on Boxing Day, 2005

Estimating Probabilities Carol is 31 years old, single, outspoken and very bright. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in antinuclear demonstrations. Representativeness population of bank tellers population of feminist bank tellers What is the probability that Carol is a feminist bank teller? What is the probability that Carol is a bank teller?

Estimating Probabilities Your friend buys three Lotto 6/49 tickets and offers you one. Which set of numbers would you choose: –7, 18, 23, 36, 41, 49 –1, 2, 3, 4, 5, 6 –10, 15, 20, 25, 30, 35

A man walks into a bar… A man who wanted a drink walked into a bar. Before he could say a word he was knocked unconscious. Why? Need to break out of mental set

How Can You… You are alone in a room with two strings hanging from the ceiling. The strings are two far apart for you to grasp them both simultaneously. Your job is to tie the two strings together. Your only tool is a pair of pliers. How can you accomplish the job? Functional Fixedness