Week 11+12+13 (M4) Flashcards
Is judgement solely dependent on formal logic?
No! That is idealized reasoning
Normative vs descriptive
Normative = ideal
Descriptive = reality
What people actually do is FAR from ideal reasoning
Inductive reasoning
+ top-down or bottom-up
Observations to general conclusion/theory
Bottom-up
specific to general
Deductive reasoning
General premise to conclusion about a specific case
Top down
General to specific
Availability heuristic
Judge frequencies of events (probabilities) using availability
- relies on memory
ex. more n or ing words
What impacts availability heuristic
Imageable things
- increase likelihood estimates
- we fear what we perceive as uncontrollable
The Von Restorff effect + what heuristic
aka isolation effect or distinctiveness principle
- memory is better for things that stand out; things that are distinctive, isolated, humorous, bizarre, etc.
availability bias
Anchoring bias + issue
Estimates of frequency - start from a point (ANCHOR) and move up or down
People even use a completely unreliable number as an anchor and go from there
Problem - hard to put aside original estimates - whether right or wrong, and even if subjects
know it is not reliable, will serve as an anchor
Heuristic
quick and easy way to judge something (not always accurate)
Representativeness heuristic + relates to…
- assume homogeneity (that all members of a category are the same) and that each member of a category is representative of that category
stereotypes
Conjunction fallacy + what heuristic
bank teller
aka support theory
People use similarity to a prototypical example, rather than probability, as a basis for judgment
Representativeness
ex. bank teller fem mvmt lady
Sunk cost fallacy
“Throwing good money after bad”
The gambler’s fallacy
+ what heuristic
the belief that prior outcomes can
influence the outcomes of probabilistic
events
“due for a crash”
representativeness heuristic
Law of large numbers
things do tend to even out in the end, proportionally, over a LOT of trials. BUT, this does not extend to small samples
Reasoning from a single case to an entire population
AKA “The man who” argument
My grandma smoked every day but died in her sleep…
- representativeness heuristic issue
- assumption of homogeneity
Hindsight bias
People think after the fact that they would have known something before the fact when they really wouldn’t have. Turning vague statements into solid predictions after the fact.
- thought you were certain in the past
I knew it all along; I told you so; hindsight is 20/20
Hindsight bias - doctor example
The doctors in Group 2, who already knew the diagnosis, were told to IGNORE it, and to just do the task on the basis of the evidence at hand.
Results - Doctors who already knew the diagnosis assigned probabilities to that diagnosis THREE TIMES HIGHER than did the doctors who didn’t know the diagnosis.
Even though the actual diagnosis was the LEAST likely disease, given the symptoms.
The Better-than-average Effect
AKA: Illusory Superiority
People, on average, think that they are better
than average.
– Of course, it is impossible for everyone to be
better than average
– Exception is the clinically depressed
Covariation
Illusions of covariation
People project their own prior theories onto the data - see only the patterns you expect to see.
e.g. interpreting Rorschach tests
Data vs. theory driven covariation interpretations
Data-driven
- when participants
have NO prior
expectations or beliefs
about the things being
judged
- systematic
- conservative
(low estimates
unless correlation is
strong)
Theory-driven
- when participants DO
have prior expectations
or beliefs about the
things being judged
- inaccurate,
variable
- over-estimate
Confirmation bias - when detecting covariation
– People don’t look at all the evidence, just a
subset
– More attentive to evidence that CONFIRMS our
beliefs than to evidence that might falsify them
When detecting covariation issues with consulting your memory schemata
– helps to remember examples that fit your prior belief, don’t remember counter examples – leads
to availability effect for further reasoning
Base rate + diagnositc info
Edgar is a quiet man, who likes to read poetry. Is he more likely to be an English professor or a truck driver?
how DIAGNOSTIC is this? (what proportion
of English professors fit this description, and
what proportion of truck drivers fit this
description)
AND
what is the BASE RATE for English professors
and truck drivers
Base rate neglect
+ what heuristic do we use instead
we tend to use representativeness and ignore the base rate
You need to ask: Out of how many?
ex. the bank teller feminist thing
Bayes theorem base rates
…
Base rates + diagnostic info = which do we pick
If given JUST the base rates, people use them effectively.
If given JUST the diagnostic information, people use it (following categories, stereotypes, heuristics…)
BUT give BOTH base rates and diagnostic information, people tend to ignore the base rates
Dual system hypothesis
System 1 = heuristics
System 2 = less biased but more effortful
Data format
- Framing effects
- Triggering statistical knowledge
Training in statistical reasoning works
What is reasoning
Testing and adjusting our beliefs
Logical vs. realistic reasoning
Logic (ideal)
– Logical reasoning
– Rational thinking
– Utility theory
What people do
– Biases
– Heuristics
– Errors
– Irrational thinking
– Pragmatic reasoning
Issues with adjusting our beliefs
- overconfidence
- belief perseverance
- confirmation bias
Overconfidence
Both experts and novices are more confident in their judgments than is justifiable
Belief perseverance
We don’t want to let go, even in the face of strong evidence
Confirmation bias
people test their hypotheses by choosing tests that confirm them, rather than tests that would disconfirm them