Decisions, Judgements, and Reasoning

Chapter 11 of psych 270

What is confirmation bias

We tend to see out confirmatory evidence to support our beliefs, and we do not seek out or ignore evidence that contradicts our beliefs

What are errors

The cost of quick, efficient mental processing

What is dual process view

System 1 and System 2

What is system 1 thinking

Intuitive

-Quick and reflexive

-Little mental effort required

-Relies on heuristics

Fast and frugal

What is system 2 thinking

Analytical

-Slow and reflective, deliberate

-Requires mental effort

Uses mental energy

What does being cognitive misers mean

Allow us to simplify our world and attend primarily to what is meaningful and manageable

-Heuristics often work very well, or good enough

-There can also be problems with heuristics thinking

What is the availability heuristic

Estimates are influenced by the ease with which relevant examples can be remembered

-A simple shortcut where we make estimates based on what we can think of

Examples:

-What proportion of households in Canada have an iPad?

-How likely are you to be harmed by a terrorist attack?

What are the biases within the availability heuristic

General world knowledge

Familiarity bias

Salience and vividness biases

What is general world knowledge

Our existing knowledge factors into our estimates

Example: Estimate the ratio of the number of Chevrolets sold to the number of Cadillac’s sold

-People may incorporate what they know about these vehicles into their estimate: the cost and how many people are likely to be able to afford a Cadillac

What is familiarity bias

Judging events as more frequent or important because they are more familiar

Familiarity affects our judgement beyond estimates of frequency (food additives; political candidates)

Tversky & Kahneman

What is Tversky & Kahneman study in familiarity bias

Gave people lists with 39 names (19 women’s names and 20 men’s names per list)

Some participants had to recall names, some had to estimate if there were more men’s than women’s names

In some lists the men’s names were famous (but not the women’s), in others the women’s names were famous (but not the men’s)

Results: people could recall more famous (12/19) than non-famous names (8/20)

Results: people estimated that there were more names in the men’s or women’s list if the names were famous

What is salience and vividness biases

A particularly notable or vivid memory influences judgments about the frequency or likelihood of such events

Is it safe to travel by car or airplane?

-25 times safer to travel by airplane

What is the simulation heuristic

A mental construction or imaging of outcomes; a forecasting of how some event will turn out or how it might have turned out under different circumstances

-Also includes possible events

-Guided by the ease with which the possible outcomes come to mind or can be imagined

When imaging a scenario, alternatives that are difficult to imagine or seem less plausible are judged as unlikely to occur

-If an alternative is difficult to imagine no mental scenario will be formed, therefore it will not be judged as likely or unlikely to occur at all

-If you cannot imagine possibility A, you cannot consider possibility A

Kahneman & Tversky (1982) study

What is Kahneman & Tversky (1982)

Mr. Crane and Mr. Tees were scheduled to leave the airport on different flights, at the same time

They traveled from town in the same limousine, were caught in a traffic jam, and arrived at the airport 30 minutes after the scheduled departure time of their flights

Mr. Crane is told that his flight left on time. Mr. Tees is told that his flight was delayed, and just left five minutes ago

Who is more upset, Mr. Crane or Mr. Tees?

What is the representativeness heuristic

An estimate of the probability of an event is determined by one of two features:

-How similar the event is to the population of events it came from

-And/or whether the event seems similar to the process that produced it

Representativeness of the parent population

-Kahneman & Tversky (1972)

What is random processes

If a coin is tossed 6 times, which is more likely to occur?

H H H T T T or H H T H T T

What is Kahneman & Tversky study (1972)

There are two hospitals in a town. In one, about 45 babies are born each day. In the other, only about 15

About 50% of all babies are boys, although on any day this percentage may be higher or lower

Across one year, the hospitals recorded the number of days on which 60% or more of the babies were male

Which hospital do you think had more such days?

Results:

-28/50 Ps said that hospitals would be the same

-12/50 Ps said it was the larger hospital

-10/12 Ps said it was the smaller hospital

What is ignoring base rates

Kahneman & Tversky (1973) study

What is Kahneman & Tversky (1973) study

Read various personality descriptions to people

-Ps were asked to estimate the probability that the described person was a member of one or another profession

-Psychologists interviewed and tested the personalities of 30 engineers and 70 lawyers

What is the probability that the person is an engineer?

-Jack is a 45-year-old man. He is married and has four children. He is generally conservative careful, and ambitious. He shows no interest in political and social issues and spends most of his free time on his many hobbies, which include home carpentry, sailing, and mathematical puzzles

-A person named Bill was randomly selected from the roomful of 100 people

What does thinking of heuristics adaptively

Heuristics are adaptive

-Used to save mental resources

-They work!

What are fast and frugal heuristics

Satisficing, the recognition heuristic, “take the best” heuristic

What is satisficing

Make a decision by taking the first solution that satisfies some criterion we may have

-The “good enough” heuristics

What is the recognition heuristic

Base a decision on whether we recognize the thing to be judged

What is “take the best” heuristic

Decide between alternatives based on the first useful information we find