Logic in Infants

The ability of infants to perform disjunctive syllogism

Allison Hyland, 2012Supervised by Dr. Susan Carey and Shilpa Mody

Presentation OverviewDescription of Disjunctive

SyllogismReview of previous studiesMethods of our studyResultsImplicationsPotential future studiesQuestions

Implications of this researchChrysippus Dog AnecdoteHow can we do this?What kinds of symbols are

available in the mind?What computational tools and

devices do we have access to?

Disjunctive SyllogismSimple argument formProcess of elimination

◦A or B◦Not B◦Must be A

Also called modus tollendo ponens

Mutually Exclusive (only one possibility can be correct)

Previous StudiesHalberda, 2003: The

development of a word-learning strategy

Looking time study

Results

Still leaves the question:◦Did the infants use Disjunctive

Syllogism (logic) or simply match novel to novel without performing logic (N3C)

◦Why did 14 month olds exhibit opposite behavior?

Previous StudiesHalberda, 2006: Is this a dax

which I see before me?In response to unaddressed

issues of previous studyAnother looking time study with

more stringent statistical techniques

Done first on adults to indicate if his procedure was efficient

Results: General task success

Results: double checks

Halberda, 2006-cont.Did similar procedure with

preschool-aged childrenPreferential pointing method and

quantitative evaluation of number of double-checks

Results: general task success

Results: double checking success

Previous StudiesDisjunctive syllogism just for word-

learning? Or domain general?Waxman & Booth, 2000: Principles

that are invoked during the acquisition of words but not facts

Tested whether children can map novel words to novel objects/novel facts to novel objects AND whether they could extend the significance of these novel objects to similar objects in each case

Results

Previous StudiesDomain Specificity?Spiegel, Yamaguchi, Heverly-Fitt,

Halberda, 2009: Children’s use of logical inference in mapping novel voices to novel characters

Preferential pointing technique in children

Results

Still leaves the question:◦When do children develop the ability

to perform disjunctive syllogism in simple, A or B situations?

Our StudyWe are investigating whether infants

can reason about possibilities using the process of elimination. They will see that a toy is being hidden in one of two locations, but will not know which one it is in. Can they use visual or verbal information about where the object is not to determine where it is?

How will we do this?

Methods: Based on Previous StudyCall, 2004: Inferences about the

location of food in the great apes2 variables:

◦Visual clue as to location of where food was/was not

◦Auditory clue as to location of where food was/was not

Results suggests inferential reasoning

Our Methods and ProcedureSubjectPhysical set up2 Practice Trials4 Test TrialsTypes of EvidenceCounterbalancing of Conditions:

◦PL, PR, VL, VR

What does this look like?

Results

12 14 16 18 20 22 240%

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Percent correct by age

Results

trial1 trial2 trial3 trial40%

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Percent correct by trial (23-month-olds)

Conclusions so far

Not very many childrenTentatively our data supports

that children aged between 23 and 24 months can successfully perform disjunctive syllogism

ImplicationsResults at 23 monthsBaseline and definitive age at

which children can perform this simple logic

Potential Future StudiesYounger ChildrenVerbal Cues

Questions?

References Call, Josep. (2004). Inferences about the location of food in the

great apes (pan paniscus, pan troglodytes, gorilla gorilla, and pongo pygmaeus). Journal of Comparative Psychology, 118(2), 232-241.

Halberda, Justin. (2003). The development of a word-learning strategy. Cognition, 87(2003), B23-B34.

Halberda, Justin. (2006). Is this a dax which I see before me? Use of the logical argument disjunctive syllogism supports word-learning in children and adults. Cognitive Psychology, 53(2006), 310-344.

Spiegel, Chad A., Yamaguchi, Mariko, Heverly-Fitt, Sara & Halberda, Justin. (2009). Children’s use of logical inference in mapping novel voices to novel characters. Poster presented at Society for Research in Child Development, Denver, CO.

Waxman, S. & Booth, A. (2000). Principals that are invoked during the acquisition of words but not facts. Cognition, 77(2), 33-43.