# Even small children can calculate probabilities

Young children can estimate probabilities
Children develop a feeling for statistics at the age of six months

One of the most important skills of our brain is to draw general conclusions about our environment from a small amount of available data in order to avoid as many uncertainties as possible. To do this, it constantly estimates how likely an event is and thus recognizes statistical regularities. As adults, we have a rough idea of ​​the likelihood of different events. So far, however, it has been unclear at what age we are able to estimate probabilities. Scientists at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig have now shown that babies as young as six months have a feeling for probabilities.

For a lifetime we have to make decisions again and again and weigh up the probabilities. By learning to assess which event is more likely to occur than another, we become better at assessing risks and aligning our actions accordingly. But at what age do we start to develop a feeling for the stochastics of events? Are babies able to do this?

Scientists from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig and the University of Uppsala, Sweden, have now found that babies as young as six months can evaluate probabilities. The little ones are already able to filter from a lot of blue and yellow balls which color is the more common and therefore the one that is more likely to be drawn. "The ability to estimate probabilities seems to develop around the age of six months," said Ezgi Kayhan, neuroscientist at the Max Planck Institute in Leipzig and head of the underlying study. In a previous study, four-month-old babies were unable to accomplish this task. So they don't seem to be sensitive to probabilities yet.

The neuroscientists examined these relationships using animated films that showed a total of 75 babies aged six, twelve and 18 months. It showed a machine filled with a lot of balls, many of which were blue, a few yellow - similar to a lottery machine. This spat many of the mainly blue balls in one basket, but many yellow balls in a second. It was 625 times less likely that the machine would spit out a yellow instead of a blue ball. The second container full of yellow balls thus reflected an event that is extremely unlikely to occur.

While the babies were watching the short films, the researchers used the so-called eye-tracking method to see which of the two baskets the little test subjects looked at longer - the more likely or the less likely. “We found that babies, regardless of age, looked at the less likely option longer. They were probably astonished that it consisted mainly of the very few yellow balls, so it was a very unlikely event, ”said the researcher. In order to ensure that the little ones were no longer drawn to the yellow color, the scientists reversed the frequencies of both colors in some of the experiments or used green and red balls.

Changed probabilities
“In principle, there have already been some studies on whether toddlers are able to estimate probabilities. However, we were the first to examine the limits of this early ability, ”explains Kayhan. For this purpose, she and her team tested whether it makes a difference, how clearly the difference between the probable and the improbable variant can be seen at first glance. And indeed: When the researchers changed the ratio of blue and yellow balls and thus the chances of drawing one of the two colors, the looks of the little ones also changed. If it was only nine times more likely that the machine would spit out a blue instead of a yellow ball, the small study participants suddenly looked longer at the more likely variant, the basket with primarily blue balls.

“One explanation for this observation could be that with increasing difficulty the information for the little ones became too complex from a certain level. We know from previous studies that babies focus on objects or relationships that they know when they don't have enough time to process new and complex information, ”says Kayhan. “As soon as they have decoded them, they can devote themselves to new things.” Regardless of a possible explanation, the scientists made one thing clear from the results: One thing that makes it possible for babies to deal with probabilities depends not only on their age, but also on Ratio between a probable and improbable event. VM / HR