Psycc 134 Decision making and reasoning ch 13

Elements of a decision

judgment: to judge or form an opinion

reasoning: the process of drawing conclusions

decision: the process of choosing between alternative

inductive reasoning

the process of drawing a general conclusion based on specific observations

ex: summers reach 100 degrees , it will be 100 degrees this summer

specific cases = broad principles

deductive reasoning

the process of determining whether a specific conclusion logically follows from general statements

ex: all men are mortal. Socrates is a man. Therefore Socrate is mortal.

broad principles = specific cases

Bottom-up process for inductive reasoning

facts or observations > hypothesis > theory

ex: Dr. House

Top-down process for deductive reasoning

hypothesis > facts > conclusion

ex: Sherlock

if the premise is true, the conclusion is probably true

inductive reasoning

ex:

The temperature in

Riverside reaches 100°

every summer. > Therefore, it

will reach 100° in Riverside

this summer.

if the premise is true,

the conclusion is

definitely true

deductive reasoning

ex:

All men are mortal. Socrates is a man = therefore, socrates is mortal

Representativeness of observations

How well observations about a particular category represent al members of that category

- stronger inductive arguments

Number of observations

How many observations are made

- stronger inductive arguments

Quality of evidence

Observations can be supported by scientific evidence

- stronger inductive arguments

Confirmation bias

We look for info that supports our opinions and ignore info that refutes it

- inductive arguments are weakened by a bias to confirm (or support) our opinions

Myside bias

We evaluate evidence in a way that's biased toward our own opinions and attitudes

ex: a group FOR capital punishment "evidence of the deterring effect of capital punishment was convincing"

vs a group AGAINST capital punishment "evidence of the deterring effect of capital punishment was NOT convincing"

Backfire effect

Our support for a given opinion can be stronger when faced with facts that oppose it

Heuristics

Educated guesses, intuitive judgments, or common sense used to solve a problem quickly

Availability heuristic

- Events that come to mind more easily are judged as being more probable

ex: what is more likely to kill you? Taking a shower or a tornado? We would choose tornado because the risks associated with it come to mind more easily in in reality more people die from shower accidents

- Undue weight is given to anecdotal evidence that comes to mind more easily

ex: ur mom saying her Volvo sucks vs commercial saying it's great)

- Our conclusions are biased by evidence that is more available

ex: that noise outside must be... a little critter (watching something peaceful)... a serial killer! (Watching a horror movie)

Illusory correlations

When a relationship between two events appears to exist, but, in reality, there is little or no relationship

ex: it always rains after I wash my car

- stereotypes are a common form of illusory correlation

Representativeness heuristic

Events that are more similar to a given category are more likely to be judged as being part of that category

- base rate

- conjunction rule

- law of large numbers

we rely on representativeness to the occupation categories and ignore the base rate

ex: If Joe is weird and eccentric you are more likely to assume he is a comedian rather than a doctor despite the fact 2.5 ppl every 1000 ppl are drs and Joe really is a dr

Base rate

The relative proportion of different classes in the population

ex: 1,000,000 doctors; 800,000 lawyers; 2,500 comedians

Conjunction rule

the probability of a conjunction of two events cannot be higher than the probability of the events alone

law of large numbers

the more individuals that are randomly drawn from a population, the more representative the group will be of the entire population

syllogism

consist of two broad statements (premises) and a conclusion

categorical syllogism

statements being with "all", "no", or "some

ex: All teachers are inspiring, Prf. DZ is a teacher, Prf. DZ is inspiring

conditional syllogism

the first premise has ann "if...then" format

ex: If I study, then I will get a good grade. I studied. I will get a good grade. (If P, then Q, P, Q)

If P, then Q, P, Q

If P, then Q, not Q, not P

If P, then Q, Q, P

- it's easier to see the logic is invalid when using statements that also make it inaccurate

If P, then Q, not P, not Q

- it's easier to see that the logic is invalid when using statements that also make it inaccurate

valid syllogism

the conclusion follows logically from the premises

ex: All dogs are animals. All animals eat food. All dogs eat food. (true

not all valid syllogism are true

ex: All dogs are animals, all animals have wings, all dogs have wings (not true)

invalid syllogism

the conclusion does not follow logically from the premises

ex: all dogs are animals, some animals are small, some of the dogs are small (possibly true)

Not all invalid syllogisms are not true

ex: All dogs are animals, some animals are in space, some of the dogs are in (not true)

belief bias

the tendency to think a syllogism is valid if its conclusions are believable

falsification principle

to test a rule, it's necessary to llok for a situation that would falsify it

ex: You are given four cards. Each card has a number on one side and a letter on the other. If a card has a vowel on one side, then it has an even number on the other side.

- which cards do you need to turn over to test the rule?

cards corresponding to invalid syllogisms will not help you to test the rule

Abstract vs concrete

real life problems are easier to solve than abstract problems

Expected utility theory

assumes if people have all relevant information, they will make a decision that results in outcomes that help to achieve their goals

Framing effect

decisions are influenced by how the choices are stated

ex: beef 75% lean 25% fat, condom 95% success rate 5% failure rate

Status quo bias

the tendency to do nothing when faced with making a decision

ex: countries using OPT-IN organ donation procedure (smaller numbers) vs countries using OPT-OUT organ donation procedure (larger numbers)

Risk aversion

the tendency to avoid taking risks

Dual systems approach

idea that we may have different systems for decision making

Our decisions can be biased by other, seemingly unrelated factors