PSYC20007 Lecture Notes - Lecture 5: Paul E. Meehl, Steven Pinker, Recognition Heuristic
14 Jun 2018
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Lecture 5 - Tuesday 22 August 2017
PSYC20007 - COGNITIVE PSYCHOLOGY
LECTURE 5
JUDGMENT, DECISIONS AND REASONING
TODAY
•1. Introducing the heuristics and biases program, and its forebears
•2. The two systems and question substitution
•3. The three general-purpose heuristics: 3a. Representativeness heuristic
•3b. Availability heuristic
•3c. Affect heuristic
•4. The so-called anchoring heuristic
•5. Gigerenzer, the rationality wars, and the recognition heuristic
•6. Conclusion
•(1) So a heuristic technique, often called simply a heuristic, is any approach to problem solving,
learning, or discovery that employs a practical method not guaranteed to be optimal or perfect,
but sufficient for the immediate goals.
1. THE ‘HEURISTICS AND BIASES’ PROGRAM
•(2) Central idea: Judgment and decision-making often rests on simplifying heuristics instead of
extensive algorithmic processing.
•Heuristic: A simple procedure that helps find adequate, though often imperfect, answers to
difficult questions.
•Bias: A systematic error of judgment.
•(3) “I would say, without hesitation, if somebody were to ask me what are the most important
contributions to human life from psychology, I would identify this work as maybe number one,
and certainly in the top two or three. In fact, I would identify the work on reasoning as one of the
most important things that we've learned about anywhere. I argued at Harvard that when we
were trying to identify what should any educated person should know in the entire expanse of
knowledge, I argued unsuccessfully that the work on human cognition and probabilistic reason
should be up there as one of the first things any educated person should know. I am unqualified in
my respect for how important this work is.” -- Steven Pinker
FOREBEARS
HERBERT SIMON
•(4) Simon (1990)
•Bounded rationality: Humans reason and choose rationally, but only within the constraints
imposed by their limited search and computational capacities.
SATISFICING
•(5) Simon (1990)
•Satisficing is a short cut: pick the first satisfactory alternative, it will probably work/satisfy the
task. This is sometimes called the first heuristic.
•Satisficing: “[U]sing experience to construct an expectation of how good a solution we might
reasonably achieve, and halting search as soon as a solution is reached that meets the expectation”
PAUL MEEHL
•(6) Two major findings from Meehl (1954):
•1. Clinical prediction performs very poorly relative to statistical prediction.
•2. Clinical prediction overweights case characteristics and underweights base rates.
•Base rates: probability of a disease given that we know nothing about the person. A foolish
clinical prediction ignoring base rates: someone has symptoms with lupus symptoms. It also !
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Lecture 5 - Tuesday 22 August 2017
PSYC20007 - COGNITIVE PSYCHOLOGY
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matches (but less so) leukaemia. So most clinicians will assume you have lupus; they won’t take
into account that the likelihood of lupus is lower than leukaemia.
2. THE 2 SYSTEMS AND QUESTION SUBSTITUTION
•(8) We perceive the middle line as longer than the other two even
though they are clearly all the same. However just knowing that
they are all the same length doesn’t make the middle line actually
appear to be the same length. So the perception is insulated from
conscious control.
A FOGGY DAY
•(9) Analogy drawn between subjective assessment of probability
and of physical quantities (Eg. distance). Distance judgements are
based on data of limited validity processed by heuristics. Relative to
the picture of a car on a foggy road in front of us, we can use an
object’s clarity to estimate an object’s distance. The more clear, the
closer, the fuzzier, the further away we will say it is. This is a good heuristic but it leads to
predictable systematic errors. If it is a foggy day or there is limited visibility (as in the picture), we
tend to overestimate distances (like for the truck). This is because contours of objects are blurred.
What’s going on here? Some people attempted to take the template they’d been using to study
perception and transfer it to study the subjective assessment of probability.
TWO SYSTEMS
•(10) Picture of a woman who looks angry. We probably think she is angry. This is automatic; we
couldn’t decide to see her as not angry just as we couldn’t decide to see her as not blonde. These
thoughts are automatic, not volitional.
•(11) 17x24. An answer doesn’t immediately come to mind so we have a choice about whether to
perform the mental calculation. But if he had 2x2, the answer 4 would have come fairly
automatically.
THINKING, FAST AND SLOW
•(12) EXAMINABLE TERMINOLOGY from Evans &
Stanovich (2013). Been adapted a fair bit.
•Kahneman’s book: Describes judgement and decision
making as a combination of interaction between 2
characters: system 1 and system 2. Fast/automatic vs
effortful/slow. According to this, system 1 is constantly
feeding intuitions and feelings and understandings over to
system 2, which is mainly passive, rule based and
analytical, monitoring and generally adopting suggestions
of system 1. However system 2 will kick into action under various circumstances, such as when
system 1’s model of the world was called into question by a weird event (gorilla walking across
basketball court etc). Eg. In the example with 17x24, system 1 was not going to work this out.
•Sure we were slow for 17x24 but in other situations, system 2 can act with great speed. Eg. To
keep us from saying stupid shit (as long as not incapacitated by alcohol or tiredness or any altered
states of consciousness in general).
•(13) Question 1: A bat and ball cost $1.10. The bat costs $1.00 more than the ball. How much
does the ball cost? 10 cents.
•(14) If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to
make 100 widgets? ____ minutes. 500.
Lecture 5 - Tuesday 22 August 2017
PSYC20007 - COGNITIVE PSYCHOLOGY
•(15) In a lake, there is a patch of lily pads.
Every day, the patch doubles in size. If it takes
48 days for the patch to cover the entire lake,
how long would it take for the patch to cover
half of the lake? ______ days. 47.
•System 1 wants you to say 24 (growth in a
linear rate), but this isn’t true.
COGNITIVE REFLECTION TEST
•(16)
IMPROVING SYSTEM 2’S INTERVENTION
•(17) ensuring low cognitive load can help. Alter et al. Had half of the participants in the small
grey font and the other half in the bigger black font. Counterintuitively, the group with the small
grey font did better. So they concluded that increasing metacognitive difficulty woke up system 2
and made it function. However they only had 40 participants. And this was later refuted in 2015 I
think?
•Provide rewards to motivate participants to check their intuitive impressions.
•Ensure that participants are not simultaneously having to perform other kinds of mental effort.
•Another idea is commonly cited, but does not work: - Increase metacognitive difficulty (Alter et
al, 2007; Meyer et al, 2015)
THE PROPOSED MECHANISM OF SYSTEM 1
•(18) Question substitution postulates that when we seek an intuitive judgement to a complex
question, system 1 forms an answer to a simpler question instead and system 2 can choose to
reevaluate this.
•Question substitution: Instead of seeking the answer to some complex question, seek the answer
to an easier question you believe to be related.
•Substitute an easy-to-compute feature for a hard-to- compute feature.
3. 3 GENERAL PURPOSE HEURISTICS
REPRESENTATIVENESS HEURISTIC
•(20) Representativeness is the degree of correspondence between 2 things.
•According to this heuristic, probability judgments (the likelihood that X is a Y) are substituted
with assessments of resemblance (the degree to which X ‘looks like’ Y).
•Tversky & Kahneman: “Representativeness is an assessment of the degree of correspondence
between a sample and a population, an instance and a category, an act and an actor, or, more
generally between an outcome and a model.”
•(21) According to this heuristic, probability judgments (the likelihood that X is a Y) are
substituted with assessments of resemblance (the degree to which X ‘looks like’ Y).
•We’re asked: “How likely is it that Tom is a computer science student?”
•We substitute: “How much does Tom resemble a computer science student?”
•(22) Tversky & Kahneman, 1983
•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 of the following is more probable?
•A. Linda is a bank teller.
•B. Linda is a bank teller and is active in the feminist movement.
Document Summary
Introducing the heuristics and biases program, and its forebears: 2. Gigerenzer, the rationality wars, and the recognition heuristic: 6. In fact, i would identify the work on reasoning as one of the most important things that we"ve learned about anywhere. I am unqualified in my respect for how important this work is. -- steven pinker. Herbert simon: (4) simon (1990, bounded rationality: humans reason and choose rationally, but only within the constraints imposed by their limited search and computational capacities. Satisficing: (5) simon (1990, satisficing is a short cut: pick the first satisfactory alternative, it will probably work/satisfy the task. This is sometimes called the first heuristic: satisficing: [u]sing experience to construct an expectation of how good a solution we might reasonably achieve, and halting search as soon as a solution is reached that meets the expectation . Paul meehl: (6) two major findings from meehl (1954), 1. Clinical prediction performs very poorly relative to statistical prediction: 2.
