How the Brain Crunches Numbers, Brought to You by Sesame Street

One day last summer I was playing with my niece Emily in her kitchen. The bottom half of the refrigerator, right at her eye level, was covered in colorful letter and number magnets. And Emily, then 22 months, knew them all. I’d say, Where’s R?, and she’d point to R. What’s that? I’d ask and point, and she’d call out, four!

I was floored. It was a rare glimpse into what her young mind understands about the world. She can’t tell us what she’s thinking, after all.

I’ve been thinking about Emily and her magnets because of a new study about how childrens’ brains crunch numbers. Understanding what a number is — that the curved shape of the Arabic numeral 2 is named ‘two’, and that it has a conceptual meaning of not one thing, not three things, but two things — comes after a surprisingly long developmental process. Kids learn to recite number sequences, like 1 to 10, around age 2. (Emily counts up to 25 now, I’m proud to share.) But if you ask a 2-year-old to pick out three pieces of candy from a bowl, she’ll probably just grab a handful.

“They might be able to learn it for one piece of candy. Then it will take months for them to be able to give you two, then months after that to give you three,” says Jessica Cantlon, a neuroscientist at Rochester University. Then around age 3 or 4 they have an a-ha moment, she says. “The whole thing clicks. They make this inductive leap and understand the counting system.”

Clearly there’s a lot going on in the brain over the course of those months. And the same goes for older children learning more advanced mathematical concepts such as addition and multiplication. For years, scientists have tried to study these neural underpinnings by giving children controlled tasks while lying in a brain scanner. In 2006, for example, Cantlon and colleagues scanned 4-year-olds while they looked at geometric shapes scattered across a screen. The pictures varied either by the number or type of shapes, and it turns out that a specific region in the young brain is sensitive to changes in number.

The results are interesting because the same region, called the intraparietal sulcus or IPS, is active when adults process numbers. Subsequent imaging studies came out that supported Cantlon’s data, but still, what can these odd dot diagrams really say about learning math? “One question that’s always been hanging over our heads is whether or not those kinds of findings apply to the real world,” Cantlon says.

In a study published today in PLoS Biology, Cantlon’s team debuts an approach that relies on an educational program adored by millions of children: Sesame Street.

The researchers scanned 27 children aged 4 to 10 while they watched 20 minutes of clips from the popular television show. The nice thing about Sesame Street, Cantlon says, is that it features short segments focused on a simple lesson, such as what opposites are or what yummy words start with the letter C. Here’s one of the clips chosen for the study, showing Elmo counting to seven:

After being scanned the children took two IQ tests, one focused on math ability and the other on verbal and non-verbal reasoning. The researchers also scanned the brains of 20 adults while watching the same video.

Using statistical analyses the researchers compared each child’s brain activity over the 20 minutes with that of a group of adults. (As you’d probably expect, the brain patterns were different from one adult to another, but this variability is negligible compared to the differences between kids and adults, Cantlon says.)

Children whose activity in the IPS (that’s the region known to be involved in number processing, remember) looked more like adults’ IPS activity showed higher scores on the math test, the study found. Similarly, kids with more adult-like activity in Broca’s area, a brain region involved in speech, showed higher scores on the verbal tests. These correlations between brain activity and test scores didn’t crop up when participants performed typical brain-scanning tasks, such as matching numbers and shapes.

The findings aren’t all that surprising — they back up what’s been found about these brain regions in other work. But the new, more realistic method is exciting, experts say. “The authors have been very careful in their data analyses,” notes Daniel Ansari, associate professor of psychology at the University of Western Ontario, who studies numerical reasoning and wasn’t involved in the work. “This is a very interesting finding that will spur on many future research studies that aim to link neuroscience with education.”

For instance: Would you see differences if you scanned before and after the video? Might one type of educational program lead to better test scores than another? Why do some kids show more mature brain patterns than others? What if you scanned younger kids, would you find differences between ages 2 and 3 and 4?

Cantlon says a long-term goal might even be to use brain scans as a way to tailor interventions for kids who struggle with numbers. “When a kid is having trouble learning math in school, there could be a million different reasons for that. It could be that their understanding of numbers is weak, it could be counting, it could be that their calculation abilities are weak,” she says. “All of those different functions probably have different patterns of brain activity that accompany them.”

Outside of the lab, Cantlon is overseeing another promising naturalistic experiment: the mathematical development of her 2-year-old daughter. “She’s working on memorizing the count list,” Cantlon says. “It’s inspiring. You get a lot of ideas from just watching the way that they absorb the world.”