Week 8: Reasoning & Decision making Flashcards
What is reasoning?
The action of thinking about something in a logical (or rational) way to make a decision
– Use our existing knowledge to draw conclusions, make predictions, or construct explanations
- LOGICAL REASONING
- INFORMAL REASONING
2 types of logical reasoning:
- inductive
- deductive
Inductive reasoning
Making broad generalisations from specific observations
- reinforcement is essential
(may not always be true) e.g. dog believes he goes for a walk every day. this is reinforced. However, if the owner had a fall this can change
Deductive reasoning
Reaching a specific, logical conclusion from general statements or hypotheses
Typically structured as follows:
i. First premise (or statement) - “P1”
ii. Second premise - “P2”
iii. Inference (or conclusion)
e.g. Jude is taller than Jared (P1)
Jared is taller than Jesse (P2), conclusion = Jude is taller than Jesse
Two types of deductive reasoning:
CONDITIONAL
SYLLOGISTIC
Deductive reasoning: Conditional
(reasoning with if) – Logical operators included in premises e.g., or, and, if … then, if and only if
Deductive reasoning: Syllogistic
– Consists of two premises followed by a conclusion that is either valid or invalid
– Contains three items, with one occurring in both premises
– Premises and conclusions contain quantifiers e.g., all, some, no, some … not
Deductive: Conditional reasoning (4 types)
- modus ponens
- modus tollens
- affirmation of the consequent
- denial of the antecedent
Modus ponens
- Affirmative
ABAB
If A is true, B is true
A is true
So B is true
VALID
Modus tollens
- negative
ABBA
If A is true, B is true
B is not true
So A is not true
VALID
Affirmation of the consequent
- affirmative
- ABBA
If A is true, B is true
B is true
So A is true
INVALID
Denial of the antecedent
- negative
- ABAB
If A is true, B is true
A is not true
So B is not true
INVALID
Deductive reasoning = uninterested reasoning
- Examples of deductive reasoning do not account for:
– The goals/preferences of an individual
– An individual’s prior knowledge or expectations - Contrasts with how we reason in everyday life
(Also known as informal reasoning)
Importance of prior knowledge
Markowitz et al. (2013)
Both conclusions are invalid (affirmation of the consequent)
– But, participants were more likely to accept conclusion to PROBLEM 2 as valid
pps couldn’t think of many other reasons why a finger will be bleeding - however could come up with other reasons why a window could be broken = Importance of context
strategy to link to this: Statistical strategy
– Estimate the probability that a conclusion is valid based on what we know about the world
– PROBLEM 2 = higher probability, therefore invalid conclusion accepted
Also links: Counterexample strategy
– Try to think of counterexamples that contradict the conclusion
– PROBLEM 2 = more difficult to think of counterexamples, therefore invalid conclusion accepted
Which strategy used by pps often depended on…
Time given!!!
Limited time = used STATISTICAL strategy (less cognitively demanding)
Unlimited time = COUNTEREXAMPLE strategy (more cognitively demanding)
Deductive reasoning: Syllogistic reasoning
Jude, Jesse and Eden example
- Premises and conclusion contain quantifiers (e.g. some, all, most)
Validity of conclusion depends ONLY on whether it follows logically (validity in real-world is irrelevant)
Errors in syllogistic reasoning caused by what bias??
BELIEF BIAS
more likely to…
- accept invalid conclusions if they’re believable
- reject valid conclusions if they’re unbelievable
(end of deductive reasoning)
2 theories of logic-based reasoning
1) mental model
2) Dual-systems
Mental model
Create a visual image of the problem.
e.g. the lamp is on the right of the pad. the book is on the left of the pad. the clock is infront of the book. the pen is infront of the lamp. So the clock is to the left of the pen
Mental model assumptions
- Mental model constructed and conclusions generated
- Construct alternative models to falsify conclusion
– i.e., counterexamples - Reasoning problems that require several mental models are harder to solve
– Due to increased demands on working memory
- Construct alternative models to falsify conclusion
mental model limitations
- Does not describe how we decide which information to include in a mental model
- Premises
– Porsche right of Ferrari
– Mustang front of Porsche
– Beetle left of Porsche - Conclusion
– Beetle left of Ferrari
No definitive answer - the last premise is ambiguous
Dual-systems theories
- Unconscious - heuristic-based process (simplest conclusion asap)
- Conscious, analytical process (more analytical and time-consuming)
HEURISTIC-ANALYTIC THEORY (evans, 2006)
Dual-systems assumptions:
SINGULARITY - one single mental model considered at a time
RELEVANCE - most relevant mental modal considered based on prior knowledge
SATISFYING - Mental model evaluated by analytic system and accepted if adequate
INFORMAL reasoning
Refers to the process of everyday reasoning
– Contrasts with the artificial, logic reasoning tasks
– Is based on knowledge and experience
– Has little to do with formal logic
Content: Probabilities
Three factors influence perceived strength of a conclusion:
– Degree of previous conviction or belief
– Positive arguments have more impact than negative arguments
– Strength of the evidence
Hahn & Oaksford (2007)
Informal reasoning: Importance of 4 factors
– Content = plausibility
– Context = expert vs. non-expert
– Probabilities = possibly/probably true
– Motivation = support our viewpoint
Context: Neuroscience illusion
- Students provided mixture of “good” and “bad” explanations for psychological phenomena
– Rate how satisfied they were with each explanation- Some explanations accompanied by neuroscientific findings
Neuroscientific findings considered more “scientific”
– More complex/expensive equipment
– Assume that information about brain activity provides direct access to information about psychological processes
Motivation
- Our judgements can be distorted by our personal goals/beliefs
– Motivated by our wishes, not facts
MYSIDE BIAS: Tendency to evaluate statements with respect to our belief’s rather than on merit (belief can override facts)
Motivation: Climate change
- Tested American’s memories of:
– Previous summer (been unusually warm)
– Previous winter (been unusually cold)- Those most dismissive of global warming: Least likely to remember preceding summer had been warmer than usual
