Schemas and Heuristics
“Please your majesty,” said the knave, “I
didn’t write it and they can’t prove I did;
there’s no name signed at the end.”
“If you didn’t sign it,” said the King, “that only
makes matters much worse. You must
have meant some mischief, or else you’d
have signed your name like an honest
man.” –Lewis Carroll
Alice’s Adventures in Wonderland
• Quote illustrates how beliefs might
persevere, even in the face of
contradictory evidence (the perseverance
effect discussed last time)
• We’ll continue talking about schemas and
mental shortcuts today
Sometimes schemas can get us
into trouble
• Confirmation biases: Tendencies to
interpret, seek, and create information
that verifies our preexisting beliefs or
schemas.
• Examples of confirmation biases
– Belief perseverance: The tendency to
maintain beliefs, even after they have been
discredited.
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Perseverance Effect
• Ross et al. (1975)
• IV: Success, failure, or average feedback about
ability to detect “real” or “fake” suicide notes
• Intervention: E explained feedback was
randomly assigned (discredited belief)
• DV: Estimated how well would actually do at
task
• Results: Beliefs persevered. Estimates closely
matched false feedback Ps had received.
• Why? May think of reasons to support…takes
on life of its own.
Confirmation bias
• Our expectations also can influence how
we go about obtaining new information
about another person.
• Imagine that you are going to meet a
friend of a friend. Your friend tells you that
his friend, Dana, is very outgoing and
friendly, the life of the party. When you
meet Dana and are getting acquainted, will
that information influence what you say
and do? Some work suggests that it will.
Confirming Prior Expectations
• Snyder & Swann, 1978
• IV: Expectations about person to be
interviewed: introverted vs. extraverted
• DV: Selection of interview questions.
Slanted toward extraverted (How do you liven
things up at a party?), introverted (Have you ever felt left
out of some social group?), or neutral.
• Results: Ps asked loaded questions that
confirmed their prior expectations
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On being sane in insane places
• David Rosenhan
• +7 colleagues gained admission to mental
hospitals
• “heard voices,” false name, all else true
• Example of confirmation bias
• Stayed in hospital average of 19 days
• Most needed outside help to get out
• Read description of Tom W.
• Are clinicians exempt from bias?
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How might this apply to a clinician’s
diagnosis?
• Clinicians might look for information that
confirms their diagnosis and ignore
information that might disconfirm it.
(Example: “On being sane in insane
places” Rosenhan)
Confirmation Bias in the Clinic
• Once we have a hypothesis, it’s easy to
look for confirming evidence.
– True for clinicians, psychiatrists, etc.
– True in other contexts
• Courtroom: Lawyer or witness makes inappropriate
statement. Judge tells jury, “Disregard the
evidence.”
Self-fulfilling Prophecy
• One person’s expectations can affect the
behavior of another person.
• Self-fulfilling prophecy: The process
whereby (1) people have an expectation
about another person, which (2) influences
how they act toward that person, which (3)
leads the other person to behave in a way
that confirms people’s original
expectations.
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Example
• I expect that the students in the front row
are especially smart.
• I may give them more attention, nod,
smile, and notice when they ask
questions.
• As a consequence, students in the front
row might pay closer attention, ask more
questions, etc., thereby confirming my
expectation.
Teacher expectations
• Rosenthal & Jacobson (1968)
• Discussion
Limits of Self-fulfilling prophecies
• Self-fulfilling prophecies are
– MORE likely to occur when the interviewer is
distracted (tired, under time constraints, etc.)
– LESS likely to occur when the interviewer is
motivated to be accurate
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Heuristics
• Specific processing rules (or rules of
thumb)
Mental Shortcuts or
Heuristics
• Judgmental heuristics: Mental
shortcuts (rules of thumb) people use
to make judgments quickly and
efficiently
• Research on heuristics arose in
response to a view of humans as
rational, thoughtful decision-makers.
– Economists’ models
– Tversky & Kahneman
– Nisbett & Ross
• We will discuss a few specific heuristics
(but there are many)
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What is the difference between a
schema and a heuristic?
• Schema
– organized set of knowledge in a given domain
(knowledge structure)
– influences processing
– Ex: Rude person – related traits, expected
behaviors, expectations about own reactions, etc.
• Mental shortcut
–
–
–
–
Specific processing rule
Not necessarily tied to a particular schema
Not a “knowledge structure”
Ex: If an item is expensive, it must be good
quality.
• Exercise
Representativeness heuristic
• The tendency to assume, despite
compelling odds to the contrary, that
someone belongs to a group because
he/she resembles a typical member of
that group.
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Base-rate information
• Are there more salespeople or librarians in
the population?
• If knew that sample = 100 people and 70
were salespeople and 30 librarians, what
would you have guessed?
• Representativeness heuristic can lead us
to discount important base-rate
information (i.e., info about the frequency
of members of different categories in the
population)
Availability Heuristic
• The tendency to perceive events that
are easy to remember as more frequent
and more likely to happen than events
than are more difficult to recall.
• Which of the following are more frequent
causes of death in the U.S.?
– Homicide vs. diabetes?
– Flood vs. infectious hepatitis
– Tornados or asthma?
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People often give too much weight to vivid,
memorable information.
• Hamill, Nisbett, & Wilson (1980)
• IV: Type of information
•
Vivid, concrete atypical + statistical
•
Vivid, concrete typical + statistical
•
Control group (no information)
• DV: Positivity/negativity of attitudes toward welfare
recipients in general
• Results: Participants who read the vivid stories with
either the “atypical” or “typical” label, expressed
more UNFAVORABLE attitudes toward welfare
mothers in general than those in the control group.
Counterfactual Thinking
• We mentally change some aspect of the
past as a way of imagining what might
have been.
Study of Counterfactual Thinking
(Medvec, Madey, & Gilovich, 1995)
• Videotaped 41 athletes in the 1992 summer
Olympic Games who had won a silver or
bronze metal.
• Quasi-IV: Athlete won silver OR bronze
medal
• DV: Judges’ ratings of participants’
emotional state from “agony” to “ecstasy.”
(Judges unaware of participant’s award
status.)
• Results: Bronze medallists were rated as
happier than the silver medalists.
• Why?
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Automatic Thinking
• Most biases/heuristics operate
automatically (i.e., without conscious
awareness)
• Some are highly automatic (e.g.,
availability), whereas others (e.g.,
counterfactual thinking) appear to have
both automatic and more controlled
components
Automatic to Controlled Thinking
• Automatic thinking: nonconscious,
unintentional, involuntary, effortless
• Controlled thinking: conscious,
intentional, voluntary, effortful
Controlled Thinking
• Thought suppression: the attempt to
avoid thinking about something we
would just as soon forget
• Have you ever told yourself, “I just
won’t think about [dessert, my ex,
money…]”
• What happens?
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Example of Thought Suppression &
Ironic Processing
• Homer Simpson tries to not drink beer.
(video clip)
Ironic processing & Thought
Suppression
• Monitoring process (automatic): Search for
evidence that unwanted thought is about to pop
into consciousness.
• Operating process (controlled): Attempt to
distract self from detected unwanted thought.
• Problem: If under cognitive load (tired, hungry,
stressed, under time pressure), operating
process breaks down.
• Ironic because when we try to STOP thinking
about something, it keeps popping into our mind
(if we are under cognitive load)
How can we be better thinkers?
• Given that humans make a lot of errors in
reasoning, what can we do to improve our
thinking?
– TAKE STATISTICS!
Nisbett and colleagues found that students who
had formal training in statistics (psychology
and medicine grad students) performed better
on a test of reasoning than grad students in
disciplines (chemistry, law) requiring less
training in stats (see p. 89 of your text)
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Conclusions
• Schemas and judgmental heuristics help
us make sense of the world
• They increase our efficiency and speed
• They often operate automatically, without
conscious awareness
• But, they can sometimes lead to serious
errors in judgment!
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