Pavle Valerjev Department of psychology University of Zadar Thinking Psychology of thinking Reasoning Problem solving Judgment and decision making Undirected thinking Gilhooly 1996 Cognitive approach Thinking as ID: 634173 Download Presentation
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Deductive Reasoning: Why People Are Not Always Logical
Pavle ValerjevDepartment of psychologyUniversity of ZadarSlide2
Thinking
Psychology of thinkingReasoningProblem solvingJudgment and decision makingUndirected thinking (Gilhooly, 1996)Cognitive approach: Thinking as
a process of mental representation manipulationSlide3
Deductive reasoning
 examples
Conditional reasoningModus ponens (MP) If it rains, the streets are wet.It rains.Therefore, the streets are wet.
Logical form of MP:P <implicates> QPTherefore, Q.
Syllogistic reasoningBarbara (AAA) conclusionAll men are mortal.Socrates is a man.Therefore, Socrates is mortal. Logical form:Major premise: MaPMinor premise:
SaM
Conclusion:
SaPSlide4
Deductive reasoning
– more examples
Conditional reasoning If it rains, the streets are wet.The streets are wet.Therefore, it rains.WRONG
There is no valid conclusion.Proof? Truth table.
Syllogistic reasoningAll males are animals.Some animals are aggressive.Therefore, some males are aggressive.
WRONG CONCLUSION AGAIN
There is no valid conclusion.
Proof? Euler circles.
P
Q
If P, then Q.
1
1
1
100011001Slide5
Nondeductive types of reasoning
Inductive reasoning making generalizationsThe proportion Q of the sample has attribute A.Therefore, the proportion Q of the population has attribute A.
statistical reasoningThe proportion Q of the population has attribute A.Therefore, there is a Q probability that member x of population has attribute A.analogical reasoningP and Q are similar in respect to properties a, b. Object P has been observed to have further property x.
Therefore, Q probably has property x also.Slide6
Reasoning process
Task presentationMental representations of the situation expressed in taskMental manipulation which generates the answer
AnswerEvaluation of the answer Slide7
Cognitive biases and perceptive illusions
Cognitive biases can be as useful for research on thinking as perceptual illusions are useful for understanding perception.For example:Representativeness h
euristics → conjunction fallacy; gambler’s fallacyAvailability and simulation heuristics → hindsight bias Slide8
Slide9
Wason selection task
Example:Rule: If there is a vowel on one side of the card, then there is an even number on the opposite side.
Which cards would you turn over in order to test the rule?
P notP Q notQSlide10
Wason selection task
Original research:Wason (1966) – 4% of valid answers (P and notQ)Some other evidence of the classic effect:
Valerjev & Pedisić (2001) – 48% valid (depending on condition); 4749% typical error (P and Q)Valerjev (2000) – 14% valid; 74% typical error (participants were instructed to choose TWO cards)Valerjev & Dujmović (2016) – 4% valid; 58% typical error; and on average 85% confidence rating that they choose the right answer.Slide11
Confirmation bias and other biases
Evans (1989) – Biases in human reasoningConfirmation bias – tendency to search, interpret and remember information that confirms someone’s preconceptionsKlayman & Ha (1987) – „positive test strategy”
Nickerson (1998) – looking for supportive evidenceQuick intuitive heuristic that is useful in realistic conditionsSlide12
Other biases in
reasoningMatching bias and belief bias (Evans, 1989; 1998, 2007) Belief bias:Valerjev, Bajšanski
& Gulan (2011) Testing of belief bias and Type 1 vs Type 2 reasoningModus ponens tasks with (or without) content conflictContent conflict conditional: If the child cries, then the child is happy.Nonconflict conditional: If the child cries, then the child is sad. 2 different instructions: To make conclusions according to one’s BELIEF
To make conclusions according to LOGICAL RULESSlide13
Bias in baserate task
Dujmović & Valerjev (2016)Stereotypical baserate task (De Neys, 2014; Pennycook
, Fugelsand & Koehler, 2015)Examples:(Congruent stereotype and base rate) Person A is organized. Person A is a member of this group. The group consists of 874 accountants and 126 artists.What is more probable? Person A is an accountant or an artist?
(Incongruent stereotype and baserase)Person B is physically strong. Person B is a member of this group. The group consists of 860 teachers, and 140 boxers.What is more probable? Person B is a teacher or a boxer?Slide14
Bias in baserate task  results
Results:High proportion of stereotypical answers even in incongruent situations. Participants neglected the baserate and answered according to the content.Participants also made high metacognitive judgments (8090% confident) These judgments were negatively correlated with response times.
Faster = more confident.Slide15
Dual process theory
Cognitive biasesHeuristicsIntuitiveUnconsciousRapidLow effort
High capacityAutomatic Type 1 processesSystem 1 thinkingMental skillsAnalytical
NonintuitiveConsciousSlow and serialHigh effortLow capacity
Deliberate, access to working memoryType 2 processSystem 2 thinkingEvans (1989, 2007, 2013), Evans & Stanovich (2013), Sloman
(1996), ect.
Properties of the two thinking systems:Slide16
Some misconceptions about dual process theory
Distinction between two systems is not always so simpleThere are many dualprocess theories but they are not all the sameType 2 is not always slowThere is not only one „System 1” that performs all Type 1 processing; TASS „the set of automated subsystems” (Stanovich
, 2004)Slide17
Theories of deductive reasoning
Formal rules theoriesDomainspecific reasoning theoriesProbability theories Mental model theorySlide18
Mental model theory
JohnsonLaird (1983, 2001, 2013); JohnsonLaird & Byrne (1991)Mental model –representations of the states of affairs; possible valid conclusionsMental models in conditionalExample:
If P, then Q. If it rains, then the streets are wet. [p] [q] [it rains] [streets are wet] [¬ p] [q] [it does not rain] [streets are wet] [¬ p] [¬ q] [it does not rain] [streets are not wet]Slide19
Computational constraints and limitations described by mental model theory
Initial model representationNumber of modelsContent of modelsArrangement of modelsSlide20
Initial model
Premise can be represented with more than one modelConditional has three possible modelsInitially, only the first model is constructed to represent the conditional [it rains] [streets are wet]
… [it does not rain] [streets are wet] [it does not rain] [streets are not wet]Implication: Modus ponens (MP) is easier then Modus tollens (MT)Evidence:Valerjev (2006); Valerjev, Bajšanski
& Gulan (2013a, 2013b)Mental chronometry studiesMPs are significantly faster and more accurate than MTs Slide21
How models are generated?
Valerjev (2009)Likelihood judgment experimentConditional form: If P, then Q.Biconditional
form: If and only if P, then Q. Possible cases: P Q; P notQ; notP Q; notP notQ Slide22
Number of mental models
Greater number of models = greater working memory load = less efficiencyMT (3) is harder than MP (1)Valerjev (2006) – mental chronometry experiment Conditional and disjunctive tasks with different number of required models.
Accuracy as function of number of
m
.m. Response time as function of number of m.m.Slide23
Content effects
Models content:Abstract content, spatial relations, events, processes etc.Knauff
& JohnsonLaird (2002)Bajšanski, Valerjev, & Gulan (2011) – conditionals with updown relations and with content that was expected to be placed up or down (congruent and incongruent)Example: If the roof is up, then the cellar is down. (congruent)If the road is down then the car is up. (congruent)
Orientation effect:
F(1, 23)=17.44, p<.001Content congruence effectF(1, 23)=5.16, p<.05Slide24
Arrangement of the models
Girrotto, Mazzocco, & Tasso (1997) – different order of premises made MT more accurateValerjev,
Bajšanski, & Gulan (2010)Manipulation of the conditional orderStandard: If P, then Q.Reverse: Q, if P. Congruent and incongruent spatial content. If A is left, then B is right. MPs processed more efficient in standard orderMTs processed more efficient in reverse order
MPs and MTs have an opposite reasoning directionSlide25
Spatial priming of mental models
Valerjev, Bajšanski, & Gulan
(2013) – visual priming experiment where visual prime was antecedent and consequent in congruent or incongruent spatial order that interfered with mental model Congruent priming: If A is left, then B is right. [prime stimulus] A B Incongruent priming: If A is left, then B is right. [prime stimulus] B ACongruent prime: faster MPsIncongruent prime: faster MTsBoth effects, directionality and visualspatial priming were significant and opposite for MPs and MTsSpatial order of mental representation significantly affects reasoningSlide26
Conclusion
Many biases and computational constraints affect reasoningTwo important properties of mind:Bounded rationality which is fastSystem 1Flexibility – opportunity to switch from system 1 to system 2 if neededSlide27
References
De Neys, W. (2014). Conflict detection, dual processes, and logical intuitions: Some clarifications. Thinking & Reasoning, 20
, 169187.Dobelli, R. (2013): The Art of Thinking Clearly. New York: Harper Collins Publishers. Dujmović, M., & Valerjev, P. (2016
). Metacognitive assessment in a baserate task: The effect of Type 1 and Type 2 processing. 20th Days of Psychology in Zadar. Zadar, 1921.05.2016.
Evans, J. St. B. T. (1989). Bias in Human Reasoning: Causes and Consequences. Hove: LEA. Evans, J. St. B. T. (1998). Matching Bias in Conditional Reasoning: Do We Understand it After 25 Years? Thinking & Reasoning, 4,1, 45110.Evans, J. St. B. T. (2007). Hypothetical Thinking : Dual Processes in Reasoning and
Judgement

Essays
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Press.Evans, J. St. B. T. (2009). How many dualprocess theories do we need? One, two, or many? In J. S. B. T. Evans & K. Frankish (Eds.), In two minds: Dual processes and beyond (pp. 3354). New York, NY, US: Oxford University Press. Evans, J. St. B. T. (2012). Questions and challenges for the new psychology of reasoning. Thinking & Reasoning, 18, 1, 5–31.Evans, J. St. B. T. (2013). Dualprocess theories of deductive reasoning: Facts and fallacies. In K. J. Holyoak and R. G. Morrison (Eds.), The Oxford Handbook of Thinking and Reasoning. Oxford: Oxford University Press. Evans, J. St. B. T., & Stanovich, K. E. (2013). DualProcess Theories of Higher Cognition: Advancing the Debate. Perspectives on Psychological Science, 8, 3, 223–241.Gilhooly, K. J. (1996). Thinking: Directed, Undirected and Creative. London: Academic Press.JohnsonLaird, P. N., & Byrne, R. M. J. (1991). Deduction. Hillsdale: Erlbaum. JohnsonLaird, P. N. (2013). Inference with mental models. In K. J. Holyoak and R. G. Morrison (Eds.), The Oxford Handbook of Thinking and Reasoning. Oxford: Oxford University Press. Nickerson, R. S. (1998). Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology, 2, 2, 175220.Sloman, S. A. (1996) The empirical case for two systems of reasoning. Psychological Bulletin, 119, 3–22.Valerjev, P. (2000). Wasonov izborni zadatak: Stabilnost efekata pristranosti i tematskog materijala. [Wason selection task: Stability of bias and thematic material effects]. Radovi: Razdio filozofije, psihologije, sociologije i pedagogije, 39, 16, 97111.Valerjev, P. (2006). Deduction and Conditionals: A Mental Chronometry Experiment. Psihologijske teme. 15, 1, 151176. Valerjev, P., Bajšanski, I., & Gulan, T. (2011). Logičko i sadržajno zaključivanje: efekti upute i sadržajne konfliktnosti [Logical and content reasoning: the effects of instruction and content conflict]. Savremeni trendovi u psihologiji. Novi Sad, 1416. 10. 2011.Valerjev, P., Bajšanski, I., & Gulan, T. (2013a). Directionality of conditional and accuracy of reasoning. Suvremena psihologija 16, 1
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Metacognitive judgments during solving of
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task
.
Unpublished
.
Valerjev
, P. &
Pedisić
, A. (2002).
Wasonov
izborni
zadatak

utjecaj
upute
,
tipova
kondicionala
i
tematskog
materijala
. [
Wason
Selection Task  Influence of Instruction, Conditional Types and Thematic Material].
Radovi
:
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filozofije
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psihologije
,
sociologije
i
pedagogije
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, 17, 4564
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