judgement & decision making Flashcards
6 Forms of Thinking
- problem solving
- decision making
- judgement
- inductive reasoning
- deductive reasoning
- informal reasoning
Define Judgement
- “An assessment of the probability of a given event occurring based on incomplete information” (Eysenck & Keane, 2015)
- deciding on likelihood of various events using incomplete info
- what matters in judgement is accuracy
Define Decision Making
- “Making a selection from various options; if full information is unavailable, judgement is required” (Eysenck & Keane, 2015)
- selecting one option from several possibilities
- factors involved in DM depend on importance of the decision
Define Problem Solving
Cog activity that involves moving from the recognition of a problem through a series of steps to the solution
Define Deductive Reasoning
- deciding what conclusions follow necessarily
- provided that various statements are assumed true
- a form of reasoning that’s supposed to be based on logic
- something is true if it follows a rule/fact
- begins with a theory, supports it with observation and eventually arrives at a confirmation
- e.g. if beverages can be drank through straws, then soup is a beverage
Define Inductive Reasoning
- deciding whether certain statements or hypotheses are true on the basis of the available info
- used by scientists & detectives
- not guaranteed to produce valid conclusions
- something is true if it follows a patten/trend
- begins with an observation, supports it with patterns and then arrives at a hypothesis or theory
- e.g. everyone is eating soup, so soup must be tasty
Define Informal Reasoning
- evaluating the strength of arguments by taking account of one’s knowledge & experience
Iowa Gambling Task
- One interesting outcome: how often people decide on the “high-risk” decks (A/B) or the “low-risk” decks (C/D)
- Another interesting outcome: how long it took people to decide before they made a low or high-risk decision
What it’s used for
Bayes’ Theorem
Rev Thomas Bayes:
* used in situations with two possible beliefs or hypotheses (e.g. X is lying vs X is not lying)
* shows how new info/data change probabilities of each hypothesis being correct
What is the formula?
Bayes’ Theorum Formula
p(Ha/D) = p(Ha) x p(D/Ha)
(over) . (over) . (over)
p(Hb/D) . p(Hb) . p(D/Hb)
1 probabilties we want to calculate
2 prior odds
3 data given hypothesis
Bayes’ Theorum: 2 things that need to be done
- assess relative probabilities of the 2 hypotheses before the data are obtained (prior odds)
- need to calculate relative probabilities of obtaining the observed data under each hypothesis (likelihood ratio)
Bayes’ Theorum: What Does it Evaluate?
The probability of observing the data (D), if hypothesis A is correct, written as p(D/Ha), and if hypothesis B is correct, written p(H/Db)
(a & b = smaller & lower)
Bayes’ Theorum: What is it Expressed as?
An odds ratio
Bayes’ Theorum: What each Part of the Formula Means
1 (left):
* relative probabilities of hyp A & B in light of the new data
* probabilities we want to calculate
2 (middle):
* prior odds of each hyp being before the data were collected
3 (right):
* likelihood ratio based on probability of the data given each hyp
relative probs = prior odds x likelihood ratio
What is Base-rate Information?
The relative frequency of an event within a given population
What is the Taxi Cab Problem?
(Kahneman & Tversky, 1972):
* taxi cab in hit & run
* eye witness claims cab was blue
* city has 2 taxi companies: blue (15%) & green (85%)
* EW correctly identifies blue cab 80% of the time (but wrong 20%)
* what’s the probability the taxi was blue?
What did the Taxi Cab Problem Find?
(Kahneman & Tversky, 1972):
* shows how the base rate is neglected (i.e. prior odds)
* most ppts ignored the base-rate info about the relative numbers of green & blue cabs
* ppts only considered the witness’s evidence
* ppts concluded an 80% likelihood the taxi was blue rather than green
Calculate the Taxi Cab Problem using Bayes’ Theorum
0.15 x 0.80 = 0.12
(over) (over) (over)
0.85 . 0.20 . 0.17
odds ratio = 12.17
chance taxi is blue = 41% (12/29)
chance taxi is green = 59%
Prior odds:
p(Ha) = 0.15 (probability cab is blue)
p(Hb) = 0.85 (probability cab is green)
Data given the hypothesis:
p(D|Ha) = 0.8 (probability cab is blue when it is blue)
p(D|Hb) = 0.2 (probability cab is green when it is blue)
Bayes’ Theorem:
0.15 x 0.8 = 0.12 = 0.41 (41%) (probability cab was blue)
0.85 0.2 0.17
Heuristics Definition (Tversky & Kahneman, 1974)
Most people use heuristics (rules of thumb) in judgement tasks
Heuristics Definition (Eysenck & Keane, 2010)
Rules of thumb that are cognitively undemanding & often approximate accurate answers
Representiveness Heuristic: 2 Definitions & 1 Reason for Usage
Kahneman & Tversky (1973):
The assumption that an object/individual belongs to a specified category because it’s representative (typical) of that category
Kellogg (1995):
“Events that are representative or typical of a class are assigned a higher probability of occurrence”
Used for:
Can be used as an alternative strategy when participants show base-rate neglect
Example:
* Jack is a 45-year-old man. He is married & has 4 children. He is generally conservative, careful, & ambitious. He shows no interest in political & social issues & spends most of his free time on his many hobbies, which include home carpentry, sailing, & numerical puzzles
* 70 such descriptions are of lawyers; 30 of engineers- Is Jack a Lawyer or Engineer?
Define Conjuction Fallacy
(Tversky & Kahneman, 1983)
Eysenck & Keane (2015):
“The mistaken assumption that the probability of a conjunction of two events (A & B) is greater than the probability of one of them (A or B)”
Example: (Manktelow, 2012):
* Linda is 31 years old, single, outspoken, & very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination & social justice, & also participated in anti-nuclear demonstrations
* how would you best describe Linda: - a feminist- a bank teller- a feminist & a bank teller?
* most ppts believed it more probable that Linda was a feminist & a bank teller rather than a feminist or a bank teller