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Explaining Apparent Infant Numerical Competence in Terms of Object Representation Tony J. Simon Neuroscience Center National Institute on Drug Abuse Bethesda, MD 20983 USA tjsimon@mindspring.com. The Innate Numerical Competence Claim.
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Explaining Apparent Infant Numerical • Competence in Terms of Object Representation • Tony J. Simon • Neuroscience Center • National Institute on Drug Abuse • Bethesda, MD 20983 USA • tjsimon@mindspring.com
The Innate Numerical Competence Claim • “Humans innately possess the capacity to perform simple arithmetical calculations......... Infants possess true numerical concepts: they have access to the ordering of numerical relationships between small numbers. They can calculate the results of simple arithmetical operations of small numbers of items” Wynn (1992).
13 12 1+1=1 11 2-1=2 "Addition" 10 "Subtraction" 9 8 1+1=2 2-1=1 7 6 1 object 2 objects Number of Objects Remaining Simon et al. (1995) Replication of Wynn (1992)
Object Representation Theory • Simon (1997) “Non-Numerical” Account • 4 documented infant competencies sufficient for observed behavior. • Object Individuation (perceive/represent unitary objects) • Physical Reasoning (object permanence) • Abstract Representation (spatiotemporal object coding) • Memory (object/event comparison) • If OR Theory is right it must demonstrate 2 things: • infants, like those in the studies, must possess these abilities • these abilities are sufficient to generate the observed behavior • topic of this presentation
The INFANT Model • Simon (1998) clear replication by INFANT of all key findings • Built in ACT-R 3, models Simon et al. (1995) study • Individuation/Representation • Object-File” token created for each visible entity • spatial rep’n (location, motion, support) by separate events in task • Memory • Same Object-File encodes record of hidden/removed object
INFANT - The Model • Physical Reasoning • Create spatiotemporal prediction for Memory Object-Files • implements object permanence • Verify predictions for “unhidden”: entities • 1-to-1 Object File match - Memory with new Physical O.F. • Spatial/Object searches for disappearance/reappearance outcomes • Time to execute actions affected by activation of objects in memory • activation grows & decays with #/frequency of processing events
The Strange Case of “Magical Appearance” • Wynn & Chiang (1998) report a gap in infants’ object knowledge • LT not longer when an object impossibly appears than possible case • conclude infants must be unable to detect/understand this violation
Object Representation Failure in MA, Or Not? • OR predicts babies will detect MA impossibility • obviously, 1-1=1 will be processed just like 2-1=2 • shouldn’t that produce wrong data - longer LT for impossible task? • INFANT does respond to impossible MA outcome like other tasks • there is no failure of impossibility detection or object representation • yet looking times are just like Wynn & Chiang data!
INFANT vs Wynn & Chiang (1998) • INFANT reproduces Wynn & Chiang’s habituation results:
INFANT vs Wynn & Chiang (1998) • … and all the condition comparisons!
Object Representation Failure, Or Not? • So why isn’t impossible MA looking time longer than possible EA? • In 2-1=2 vs 2-1=1 procedure is identical until outcome • extra actions needed to resolve violation create longer looking time • But 1-1=1 (MA) gets compared to 1+0=1 (EA), not to 1-1=0 (ED)! • the single object in MA is processed very differently from that in EA • LT differences due to task comparison, not failure of MA detection • different actions & activations during tasks create similar LTs
OR Theory Explains the Puzzle • The original “number” experiments compare identical tasks • The magical appearance experiment compares different tasks • The object in MA (1-1=1) has high activation - actions execute quickly • The object in EA (1+0=1) has low activation - actions execute slowly • different number of actions required by different tasks take same time • Infants aren’t failing to detect MA violation, they treat it like experts • object representation is stronger in MA relative to EA, not faulty! • Only a detailed process theory like OR can explain the puzzle • looking time just describes, does not explain behavior
So, Where Do Numerical Abilities Come From? • Numerical ability foundations: 4 early-developing infant competencies • When presented with particular tasks they compute representations & generate behavior that appears, but is not, numerical (Clever Hans). • Object Representation Theory is coherent, parsimonious account: • explains all existing data, resolves puzzling inconsistencies • based on existing, documented, human infant competencies • foundation for construction of domain-specific numerical competence • consistent with neural development trajectory (Simon, in press)