The emergence of probabilistic reasoning in very young infants


How do people make such rich inferences from such sparse data? Recent research has explored this inferential ability by investigating probabilistic reasoning in infancy. For example, 8- and 11-month-old infants can make inferences from samples to populations and vice versa (Denison & Xu, 2010a; Xu & Garcia, 2008). The current experiment investigates the developmental origins of this probabilistic inference mechanism with 4- and 6-month-old infants. Infants were shown 2 large boxes, 1 containing a ratio of 4 pink to 1 yellow balls, the other containing the opposite ratio. The experimenter sampled from, e.g., the mostly pink box, and removed either 4 pink and 1 yellow or 4 yellow and 1 pink ball on alternating trials. 6- but not 4-month-olds looked longer at the 4 yellow and 1 pink ball sample (the improbable outcome) than the 1 yellow and 4 pink ball sample (the probable outcome).

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