Cognition
Making Decisions: Heuristics
A “rule of thumb” that becomes the basis for a decision
(a mental shortcut)
Does the letter “k” appear more often as the
first or third letter of a word in English usage?
The letter “k” appears as the third letter in a
The Availability Heuristic
Basing judgments off of I
nformation that ismore readily available in our memory (or more recent)
In the United States, are you more
likely to die from…..
Falling airplane parts or shark attack?
Homicide and car accidents combined or diabetes and stomach
cancer combined?
Being struck by lightning or killed by tornado? A bear attack or a bee attack?
Answers:
Americans are 30 times more likely to be killed by falling airplane parts than
killed by a shark
Diabetes and stomach cancer deaths outnumber murder and car accident
deaths by a 2:1 ratio
More Americans are killed each year by lightning strike than are killed by
tornados.
12 times as many Americans are killed by bee attacks than by bears (120x as
many than are killed by a black bear!)
Linda is 31 years old, single, outspoken,
and very bright. She majored in
philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations
Which is more likely:
A) Linda is a bank teller
B) Linda is a bank teller and an activist in the
The Representativeness Heuristic
A rule of thumb where similarity to a
prototype or similar situation dictates a decision.
(Kahneman and Tversky, 1973)
Our prototypes inform our decisions instead
The Representativeness Heuristic
A die has four green sides and two red
sides. You will be paid $25 if one of two sequences is rolled: RGRRR or GRGRRR
Dr. Swinkel’s cousin, Rudy, is a bit on the peculiar side. He has unusual
tastes in movies and art, he is married to a performer, and he has tattoos on various parts of his body. In his spare time, Rudy takes yoga classes and likes to collect old records. An outgoing and rather boisterous
person, he has been known to act on a dare on more than one occasion.
What do you think Rudy’s occupation most likely is?
A) Farmer B) Librarian
C) Trapeze Artist D) Surgeon
The Base-Rate Fallacy
The tendency to ignore or undervalue
statistical probability and focus
Overconfidence
The tendency to overestimate the accuracy
of one’s beliefs and judgments
Political decisions (Vietnam and Iraq)
Stock brokers
Other examples?
Follow up: Situation A (1/2 class)
You’ve decided to see a concert and have
bought a $100 ticket. As you enter the stadium, you realize that you’ve lost your
ticket. You can’t prove to management that you bought a ticket. The show is not sold out. Would you spend $100 for a new
Follow up: Situation B (1/2 class)
You’ve reserved a seat for a concert for
Framing
The way an issue is posed or framed can affect
decisions and judgments
A risky surgery…
“90% of people survive the surgery”
“10% of people die while undergoing surgery”
People more surprised when a “1 in 20” event
happens versus “10 in 200”
You and a friend just spent $150 to see a
The Sunk Cost Fallacy
The false belief that one is better off
continuing to invest more resources (time, money, effort) in a cause one has already invested in.
The Gambler’s Fallacy
Tendency to assume that one is “due” for
Risk & Gain Decisions
(Handout 23-7) Conclusions? Are we “risk averse”?
People tend to avoid risks when seeking gains but
choose risks to avoid sure losses. We’re not “risk averse” but rather “loss averse”
Decision 1:
a. A sure gain of $250
b. A 25% chance of winning $1000 and a 75% chance of winning
nothing
Decision 2:
a. A sure loss of $750
Belief Perseverance
Tendency to cling to initial beliefs even in the
face of contradictory information
Examples?
The “Birther” Argument
Strengthened by Confirmation Bias
Tendency to attend to information that agrees with
