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
Overview
Schemas: Confirmation biases
„ Perseverance effect
„ Expectancy confirmation
„ Hindsight bias
„ Self-fulfilling prophecy
Mental shortcuts
„ Representativeness
„ Availability
„ Counterfactual thinking
Automatic vs. controlled thinking
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Sometimes schemas can get us into
trouble
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Confirmation biases: Tendencies to
interpret, seek, and create information that
verifies our preexisting beliefs or schemas.
Examples of confirmation biases
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Belief perseverance: The tendency to maintain
beliefs, even after they have been discredited.
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Perseverance Effect
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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.
Selecting biased evidence
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Example: You believe that people from New
York are worse drivers than people from
Massachusetts. So, you notice every time
someone with New York plates cuts you off,
turns left in front of you, speeds, etc. But, do
you notice all the people with New York plates
who *never* do any of these things?
Snyder & Swann Interview Study
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Tested the idea that people select biased
information that will confirm their prior
expectations
Interview study: Pairs of strangers led to
believe that they would interview a person who
was either extraverted (outgoing, friendly) or
introverted (shy, reserved)
Selected questions to ask
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We may confirm our expectations by
selecting biased evidence.
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Snyder & Swann, 1978
IV: Expectations about person to be
interviewed: introverted vs. extraverted
DV: Selection of interview questions. Slanted
toward extraverted, introverted, or neutral.
Results: Ps asked loaded questions that
confirmed their prior expectations
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Tom W.
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Are clinicians exempt from this kind of bias?
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How might this apply to a clinician’s
diagnosis?
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Clinicians might look for information that
confirms their diagnosis and ignore information
that might disconfirm it.
On being sane in insane places
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David Rosenhan
+7 colleagues gained admission to mental
hospitals (pseudopatients)
“heard voices,” false name, all else true
7 diagnosed with schizophrenia, 1 with manicdepressive disorder
One pseudopatient told the
interviewer that he
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“…had a close relationship with his mother but
was rather remote from his father during his
early childhood. During adolescence and
beyond, however, his father became a close
friend, while his relationship with his mother
cooled. His present relationship with his wife
was typically close and warm. Apart from
occasional angry exchanges, friction was
minimal. The children had rarely been
spanked.”
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The interviewer’s interpretation (knowing
diagnosis=schizophrenia)
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This white 39 year old male…manifests a long history
of considerable ambivalence in close relationships,
which begins in early childhood. A warm relationship
with his mother cools during his adolescence. A distant
relationship to his father is described as becoming very
intense. Affective stability is absent. His attempts to
control emotionality with his wife and children are
punctuated by angry outbursts and, in the case of the
children, spankings. And while he says he has several
good friends, one senses considerable ambivalence
embedded in those relationships as well.
Expectancy confirmation
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Not a real patient, yet clinicians interpreted his
behavior as evidence of abnormality.
Stayed in hospital avg. 19 days (longest 53 days)
Most needed outside help to be released
Exit diagnosis “schizophrenia in remission”
Expectancy confirmation
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Different hospital
Admit some pseudopatients in next 3 months
193 new patients
41 identified as “normal”
But, actually ALL admittees were real patients!
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Confirmation Bias in the Clinic
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Once we have a hypothesis, it’s easy to look for
confirming evidence.
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True for clinicians, psychiatrists, etc.
True in other contexts
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Courtroom: Lawyer or witness makes inappropriate
statement. Judge tells jury, “Disregard the evidence.”
Self-fulfilling Prophecy
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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.
Example
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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.
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Teacher expectations
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Rosenthal & Jacobson (1968)
IV: Elementary school children labeled as
“intellectual bloomers” or not labeled
DV: IQ test 8 months later
Those whom the teachers expected to do well
actually improved more than the other students.
How?
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Not conscious effort
Teachers gave more personal attention,
encouragement
Gave bloomers more difficult material to learn
Gave bloomers better feedback
Gave bloomers more chances to respond in
class
Conclusions about schemas
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Prior expectations can influence
Attention
Interpretation
„ Memory
„ Another’s behavior (self- fulfilling prophecy)
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Heuristics
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Specific processing rules (or rules of thumb)
Mental Shortcuts or Heuristics
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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
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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?
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Schema
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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
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Specific processing rule
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Not necessarily tied to a particular schema
Not a “knowledge structure”
Ex: If an item is expensive, it must be good quality.
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Steve
Representativeness heuristic
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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
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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
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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.
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Which of the following are more frequent causes
of death in the U.S.?
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People often give too much weight to vivid,
memorable information.
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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
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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)
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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
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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
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Automatic thinking: nonconscious,
unintentional, involuntary, effortless
Controlled thinking: conscious, intentional,
voluntary, effortful
Controlled Thinking
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Thought suppression: the attempt to avoid
thinking about something we would just as
soon forget
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Ironic processing & Thought
Suppression
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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.
Conclusions
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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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