Human Cognitive Processing Exam 4

Deductive Reasoning

Reasoning in situations where the conclusions can be

determined to follow with certainty from the premises

-Valid/invalid syllogisms

 Deterministic

Inductive Reasoning

Reasoning in situations in which the conclusions

follow only probabilistically from the premises

Is it going to rain today?

 Probabilistic

logical syllogisms

Consist of two premises and a conclusion – valid/invalid

A logical syllogism is a deductive argument with two premises that necessarily lead to a conclusion if the structure is valid. It’s one of the oldest and most fundamental forms of reasoning in logic.

conditional

An assertion that, if an antecedent is true, then a

consequent must be true.

 If A, then B

what are the two parts to a logical conditonal

antecent (condition, “if”, A) and consequent (result, “then”, B)

how is deductive reasoning usually tested

by asking people to state whether conditional

statements (if-then) are valid/invalid

where is activation when there is meaningful content during reasoing

Activation in left ventral prefrontal and left parietal-temporal areas

where is activation during content free reasoning

Activation in posterior parietal reasoning

-Similar activation when solving algebra problems

Content-free syllogisms

abstract, meaningless terms (like A, B, C) so that people must rely purely on logic

• All Bargs are Lorpans.

• Some Lorpans are Tervs.

• Therefore, some Bargs are Tervs.

Meaningful syllogisms

real‑world content (like “dogs,” “students,” “flowers”), which can trigger belief‑bias and make people rely on plausibility instead of logic

Example:

• All dogs are mammals.

• All mammals are animals.

• Therefore, all dogs are animals.

Modus ponens

method of deductive reasoning to affirm the antecedent

Modus Tollens

method of deductive reasoning to denying or abolishing the antecedent

which one is valid: modus tollens or modus ponens

both

affirmation of the consequent

If Joan understood the textbook, then she

would get a good grade.

 Joan got a good grade.

 Therefore, Joan understood the textbook

Joan could have gotten a good grade even

though she did not understand the textbook

 Luck, information from class etc.

 Even though textbook  good grade

 There may be other routes to a good grade

Denial of the antecedent

 If Joan understood the textbook, then she

would get a good grade.

 Joan did not understand the textbook.

 Therefore, Joan did not get a good grade.

Similar to affirmation of the consequent, this

conditional statement is invalid because it

does not exhaust other possibilities

which one is valid Affirmation of the Consequent or Denial of the Antecedent

neither

logical conditional

simply evaluating whether the conclusions follow from the premises

Wason selection task

A subject is given a conditional statement of the form

If A, then B and must choose which situations among

A, B, Not A, and Not B need to be checked to test the

truth of the conditional statement.

for ex:

you are given four cards and the rule is “if you have a card with B on it the other side must be red”

card 1: B

card 2: red

Card 3: green

Card 4: A

most people would flip B and red but the reasnoning behind that is incorrect

-you should flip B and green since there was no rule that the red card couldnt have whatever color it wants, just the B cards (the consequent had no rules)

what was the outcome of thw wason selection task

Platt (1964) – says the strongest inference in science

comes from denying invalid causes or hypotheses

-people had a lot of trouble using modus tollens

-people have particular difficulty in

recognizing the importance of exploring whether the

consequent is false

what ways can if be interpreted

 Logical interpretation

 Causal interpretation

 Probabilistic interpretation

 Permission interpretation

what is reasoning with logical quantifiers

 Elements like all or some

 Expressed in much of human knowledge

Permission Schema

Interpretation of a conditional statement in which the

antecedent specifies the situations in which the

consequent is permitted