Do infants and preschoolers quantify probabilities based on proportions?

Abstract

Most statistical problems encountered throughout life require the ability to quantify probabilities based on proportions. Recent findings on the early ontogeny of this ability have been mixed: For example, when presented with jars containing preferred and less preferred items, 12-month-olds, but not 3- and 4-years-olds, seem to rely on the proportions of objects in the jars to predict the content of samples randomly drawn out of them. Given these contrasting findings, it remains unclear what the probabilistic reasoning abilities of young children are and how they develop. In our study, we addressed this question and tested, with identical methods across age groups and similar methods to previous studies, whether 12-month-olds and 3- and 4-years-olds rely on proportions of objects to estimate probabilities of random sampling events. Results revealed that neither infants nor preschoolers do. While preschoolers' performance is in line with previous findings, infants' performance is difficult to interpret given their failure in a control condition in which the outcomes happened with certainty rather than a graded probability. More systematic studies are needed to explain why infants succeeded in a previous study but failed in our study.

Giraffes make decisions based on statistical information

“…Twelve-month old infants, for instance, can predict outcomes from a sampling event and make decisions based on the comparison of relative quantities 5 , whereas 4.5-month-olds can even account for the presence of physical constraints that could affect the sampling process 6 . Other authors suggest that reasoning about probabilities might appear much later in development, from around 5 years of age 7,8 .The ability to make statistical inferences might be important for species other than humans, to make decisions in the face of uncertainty and/or to deal with unpredictable environments. To date, however, evidence of complex statistical skills in non-human animals (hereafter, animals) is extremely scant 9,10 .…”

“…Twelve-month old infants, for instance, can predict outcomes from a sampling event and make decisions based on the comparison of relative quantities 5 , whereas 4.5-month-olds can even account for the presence of physical constraints that could affect the sampling process 6 . Other authors suggest that reasoning about probabilities might appear much later in development, from around 5 years of age 7,8 .…”