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PSYC 2650 Lecture Notes - Wason Selection Task, Confirmation Bias, Deductive Reasoning

Course Code
PSYC 2650
Dan Meegan

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Believed that humans always reasoned according to the rules of logic
Became clear that this isn't the case at all
Designed a number of tasks that look simple at first, but are in fact full of
o Observing the mistakes that people make, we can learn more about
how people reason
Wason Selection Task
o Based on causal statements such as "If this, then that" (conditional)
Aim of these puzzles is to demonstrate that often people do not reason
according to the rules of logic
Shows you that by making mistakes yourself you can get a better
understanding of the underlying reasoning processes we all use
Research shows that only 10% of those who try to solve the standard Wason
Selection Task (with the E/4 rule) are successful
o Percentage rises, though, when abstract tasks (e.g., the card task)
become easier to visualize (e.g., the plants puzzle) or allow the subject
to factor in familiar experiences (e.g., the alcohol puzzle)
Two errors occur quite often
o Confirmation bias
People always look for examples that show that the statement
is correct while neglecting to search for counterevidence (e.g.,
if the 5 card has an E on the other side, this is disconfirming
evidence for the "If E on one side, then 4 on the other side"
o People think that an "if/then" statement can be turned around
without any problem
"If you wash the car, I'll give you $20." An hour later he hands
you $20. You might assume that this obligates you to then
wash the car because you believe, "If Dad gives me $20, then I
must wash the car."
Father might simply have felt generous and handed you $20
regardless of whether you washed the car or not
Rather than using abstract logic when reasoning, people use schemes within
a certain context, or pragmatic reasoning schemata, such as those based on
the research of Cheng and Holyoak
o Imagined that your father said to you, "If you wash my car, I'll give
you $20" and concluded that you would NOT get $20 from your father
unless you washed the car, you were using permission pragmatic
Seems logical to use deductive reasoning, though remember
that the most likely conclusion is NOT necessarily valid
o Causal schema, such as that set forth in the "If I water the plant, then it
will grow" example
Some believe direct familiarity with a given area (e.g., drinking laws)
improves performance
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