Toddlers understand difference between impossible and improbable

Toddlers that are 2 and 3 years old are too young to understand words like “impossible” and “improbable.” But the concept of possibility seems to be hardwired into their brains. New research in the Proceedings of the National Academy of Sciences not only shows young children get the idea, but it demonstrates that “they learn significantly better after impossible occurrences.”
In a brief report titled “Young children distinguish the impossible from the merely improbable,” researchers say very young kids are more interested in events that are unlikely and even impossible compared to those that are likely.
The research vehicle used by Aimee E. Stahl of The College of New Jersey psychology department and Lisa Feigenson of Johns Hopkins University’s Department of Psychological and Brain Sciences was a fake gumball machine with purple and pink hair curlers clearly visible inside it. Putting a coin in appeared to cause one or the other to “randomly” fall down a chute.
They compared the learning of 335 children ages 2 and 3 after nearly identical events that were equally likely, improbable or impossible. “We found that children learned significantly better following impossible than possible events, no matter how unlikely.”
From that, they concluded even toddlers can differentiate between the “impossible and the merely improbable.”
“Even young toddlers already think about the world in terms of possibilities,” said Feigenson, who co-directs the Johns Hopkins Laboratory for Child Development. “Adults do this all the time and here we wanted to know whether even toddlers think about possible states of the world before they’ve had years of experience and before they have the language to describe these mental states.”
Is the train likely to be on time? Better hurry. Do you have enough milk for the recipe? Stop at the store on your way home. Probability is something adults juggle all the time. The question was whether young children make mental judgments or if those are solely born of time and experience.
In the “equi-probable” scenario, the visible objects in the gumball machine were a like number of pink and purple hair curlers. Inserting the coin would deliver one or the other. In the improbable condition, the machine contained many more of one type of curler than the other. There were also degrees of probability, with different numbers of each object, clear down to 39 of the purple ones and one of the pink. Impossible included all purple curlers.
“These were chosen because even much younger infants are surprised when the rare object is drawn from similar populations,” they wrote.
There were also voice prompts, such as, “There’s some purple and some pink, and that’s all that’s all that’s in there!” or “There’s some purple and that’s all that’s in there!”
The chute, though, was preloaded. So when the child inserted the coin, it was possible to get a pink curler, though the machine only contained purple. Impossible! They were also told that the rare pink curler was a “blick,” and were later asked to find it to see how well they learned the novel word. Those who saw the impossible could reliably pick out the blick.
It’s also possible, in the video, to see their surprise: wide-eyed and slack-jawed at the mystery of how something that wasn’t there came down the chute.
The researchers found that when the children who saw only purple curlers got a pink one, they learned significantly better than the children who’d gotten a more likely object. Those who’d seen a pink one and got it, not matter how long the odds were, didn’t get a boost to their learning.
“One possibility was that they would learn well from the improbable events, but even better from the impossible events,” said co-author Aimee Stahl, a former doctoral student in Feigenson’s lab who is now an associate professor of psychology at The College of New Jersey. “But what we found was that they actually don’t learn from the unlikely, improbable events. They only learn if they experienced the impossible event.”
Feigenson and Stahl believe that children learn after impossible events because they are searching for explanations. The improbable can surprise you, but doesn’t demand an explanation. “Impossible events require kids to reevaluate what they thought they knew,” they said in the release.
Make them puzzle over things, the duo said.
“These results are so interesting because they show that when children see events in the world that they can’t explain, it instills in them a drive for information that they can use to reconcile their prior model of the world with what they’ve just seen,” said Feigenson. “Scientifically, these findings are exciting because they suggest that humans are equipped from the get-go to think about whether things are possible or unlikely or just can’t happen.”
Andrew Shtulman, a professor at Occidental College who didn’t participate in the study, told NPR that the research bolsters findings that kids learn better when they meet the unexpected.
“It elicits a level of surprise that leads to more attention, better encoding of the events, and better retention of those events later on,” he said, but added that it’s harder for young children to distinguish improbable and impossible events without physical evidence, like the appearance of a pink blick from a container filled only with purple containers. Instead, “anything that violates their expectations, they deny is possible,” per Shtulman.
To boost learning, he told NPR to “violate their expectations” before introducing information you want them to keep.
Next, the researchers hope to explore ways that parents and teachers can make their own “heightened learning moments” for kids.