Scientific Method / Science & Exploration

Research shows infants intuitively grasp statistics

New research published in last week's PNAS shows that infants as young as 8 …

One of the hallmarks of human learning is our ability to make inductive inferences using only a small set of data. An example of this ability given by researchers that authored a recent PNAS publication is that early humans may have only tasted a few berries on a given tree before concluding that all berries from this type of tree are edible. According to the authors "this type of statistical inference (going from samples to populations, and from populations to samples) is present in virtually every domain of learning." One open question in the field of human learning is: where does this ability to make such inferences come from?

The researchers, located at the University of British Columbia, looked at how well, if at all, eight month old infants could grasp the concept of basic statistics. Now, clearly you can't ask an eight month old child what they feel about the probability distribution of crayon colors in a box, or much of anything at all. To get around this, the researchers measured how long a child looked at results of a set of experiments. The experiments consisted simply of samples of ping-pong balls, painted red and white, taken from a large collection of balls.

In the first series of experiments the children were shown a box. The experimenter then removed five ping-pong balls from the box—four of one color, and one of the other. Once the five balls had been removed and displayed, the infants were shown the contents of the box. If the box contained mostly white balls, and the five selected balls consisted of four white and one red, the researchers observed that the infants looked at it for less time than if the five sample balls consisted of four reds and one white. This led the researchers to suggest that the longer time spent studying the results was due to the fact that the infants expected the sample to contain a majority of balls of the same color that dominated in the box. In a similar experiment, the researchers pulled the five sample balls—still four of one color, and one of the other—from their pockets as opposed to the box. Here, they found that the infants examined the results for the same amount of time, regardless of whether the distribution matched what was in the box. They conclude that this was because the infants were aware that the balls did not come from the box, and therefore had no reason to be correlated to what they could see.

The second set of experiments looked at whether or not the infants could use information about the population to predict what type of sample would be drawn from it. The setup was similar to before, but the children were allowed to see the contents of the box ahead of time. Again, five balls were drawn, and if four of the minority color were drawn, then the children would look at the results for a longer amount of time than if four of the majority color and one minority color were pulled.

The researchers conclude their paper with a list of still unanswered questions, suggesting avenues for future research. They do conclude that they have demonstrated that eight month olds are capable of making "inferences from samples to general populations, and vice-versa." They also suggest that this ability is not "entirely the result of formal education." They go on to relate a child's learning process to the scientific method. As stated in the end of the paper, "here, we provide some evidence that early in development infants are intuitive statisticians and the statistical inference mechanisms they use may be qualitatively similar to the mechanisms used in scientific inquiry." They aren't the first to think this the researchers cite others who have reached this conclusion but it's still a pretty intriguing idea.

PNAS, 2008. DOI: 10.1073/pnas.0704450105

Expand full story

You must to comment.