requires you to go beyond the information you were given; thinking also has a goal such as a solution, a decision, or a belief.
You are given some specific premises and you are asked whether those premises allow you to draw a particular conclusion, based on the principles of logic.
- provides you with all the information you need to draw a particular conclusion
- the premises are either true or false, and formal logic specifies the rules you must use in order to draw conclusions. All men are mortal
Socrates is a man
Therefore, Socrates is mortal
refers to assessing and choosing among several alternatives.
- more ambiguous
- some info may be missing or contradictory
- no clear-cut rules tell us how to proceed from the info to the conclusions
- the consequences of that decision won't be immediately apparent and you may need to take additional factors into account.
Conditional (Propositional) Reasoning:
problems tell us about the relationship between conditions.
- the relationship between enrolling in a class and the completion of a prerequisite.
- "If...then..." structure; Valid? Not valid?
consists of two statements that we must assume to be true, plus a conclusion. Major premise: All mammals are warm-blooded.
Minor premise: All black dogs are mammals.
Conclusion: Therefore, all black dogs are warm-blooded
- refer to quantities; all, none, some
- judge whither the conclusion is valid, invalid, or indeterminate
The propositional calculus
a system for categorizing the kinds of reasoning used in analyzing propositions or statements
refers to the first proposition or statement; the antecedent is contained in the "if.." part of the sentence.
refers to the proposition that comes second; it is in the consequence. The consequent is contained in the "then..." part of the sentence
Affirming the antecedent
"if..." part of the sentence is true. Leads to a valid, or correct, conclusion.
i.e. "This is an apple; therefore it's a fruit."
Affirming the consequent:
you say the "then..." part of the sentence is true. This leads to an invalid conclusion.
i.e. "This is a fruit; therefore this is an apple."
Denying the antecedent:
you say the "if..." part of the sentence is false. Denying the antecedent also leads to an invalid conclusion.
i.e. "This is not an apple; therefore this is not a fruit."
Denying the consequent:
you say "then..." part of the sentence is false. Leads to a correct conclusion
i.e. "This is not a fruit, therefore this is not an apple."
people may initially use a heuristic that is quick and generally correct
occurs in reasoning when people make judgments based on prior beliefs and general knowledge, rather than on the rules of logic.
- example of top down processing
The Standard Wason Selection Task: confirmation bias:
they would rather try to confirm a hypothesis than try to disprove it
-people who take time to carefully inspect the problem are more likely than impulsive people to select the two correct cards in this task.
general strategies that typically produce a correct solution.
If it is similar in important characteristic to the population from which it was selected.
we judge that a sample is likely if it is similar to the population from which this sample was selected.
small sample fallacy
assuming that small samples will be representative of the population from which they are selected.
how often the item occurs in the population
base rate fallacy
underemphasizing important information about base rate
states that judgments should be influenced by two factors: the base rate and the likelihood rate.
assesses whether the description is more likely to apply to Population A or Population B.
the probability of the conjunction of two events cannot be larger than the probability of either of its constituent events.
they judge the probability of the conjunction of two events to be greater than the probability of a constituent event.
-spilling hot coffee seems more probable than spilling coffee...until you identify the conjunction fallacy.
when you estimate frequency or probability in terms of how easy it is to think of relevant examples of something.
typically operates when you must compare the relative frequency of two categories; if you recognize one category you conclude that the recognized category has a higher frequency.
occurs when people believe that two variables are statistically related, even though there is no real evidence for this relationship.
Social cognition approach
we form stereotypes by means of our normal cognitive processes; motivational factors are less relevant.
Anchoring and adjustment heuristic aka anchoring effect
we begin with a first approximation, an anchor, and then we make adjustments to that number on the basis of additional info.
i.e. the snow storm where they thought it would take an hour longer than normal to get home but really the cars blocking the street made it a 3 hour ride home.
the belief- bias effect
we rely too heavily on our established beliefs
the confirmation bias
we prefer to confirm a current hypothesis, rather than to reject it
ranges within which we expect a number to fall a certain percentage of the time.
- the confidence intervals that we estimate are definitely too narrow
demonstrates that the outcome of a decision can be influenced by two factors
1. the background context of the choice
2. the way in which a question is worded (framed)
refers to people's tendencies to think about possible gains as being different from possible losses.
1. When dealing with possible gains (i.e. lives saved), people tend to avoid risks.
2. When dealing with possible losses (i.e. lives lost), people tend to seek risks.
means that people's confidence judgments are higher than they should be, based on the actual performance on the task.
Crystal ball technique
asks decision makers to imagine that a completely accurate crystal ball has determined that their favored hypothesis is actually incorrect. The decision makers must therefore search for alternative explanations for the outcome
people typically underestimate the amount of time (or money) required to complete a project; they also estimate that the task will be relatively easy to complete.
can occur when a cohesive group is so concerned about reaching a unianomous decision that members ignore potential problems, and they are overconfident that their decision will have a favorable outcome.
describes the overconfidence that one's own view is correct in a confrontational situation.
refers to our judgements about events that already happened in the past
occurs when an event has happened and we say that the event had been inevitable; we had actually "known it all along."
are people who have a maximizing decision making style; they tend to examine as many options as possible
are people who have a satisficing decision making style; they tend to settle for something that is satisfactory.
describe how people create a wide variety of heuristics to help them make useful, adaptive decisions in the real world.
if there is a default option, people will chose it.
i.e. you have to sign up to be an organ donor here, while in France you automatically are one unless you sign otherwise
operates when someone asks you to make a judgment and you don't know the answer; in this case, you substitute an answer to a similar but easier question.