Radiolab is now officially my favorite non-news radio show, surpassing even This American Life and Wait, Wait, Don't Tell Me. A few days ago, I posted about a Radiolab show about whether war was inevitable, with side trips into baboon sociology, transgender people, and fox breeding.
My partner then told me about something she had heard on NPR about babies and numbers, and it turned out to be the same people. It's wonderful, and they call it Numbers. Most of it is too detailed for this blog, but one part should be very interesting to CD people.
They discuss some attention tests with kids, the ones where a kid sits on mommy's lap and looks at stuff flashing on a screen. When the kid gets bored, as shown by looking away, they flash something else. If the kid looks back at the screen, they figure it noticed the difference.
Doing this, they can tell that a 2 to 3-month old can tell the difference between 1 and 2, between 8 and 16, and between 10 and 20, but not between 9 and 10.
The reason, they say, is that they don't think in integers, the way adults (anybody older than 3 1/2) do. We see the difference between 1 and 2 as 1. The difference between 9 and 10 is also 1. Babies and toddlers see the difference between 1 and 2 as double, and the difference between 9 and 10 is 11%, too small for them to see.
They cite a tribe (Africa? South America?) where people still think that way as adults. If you put 1 stone on the left and 9 stones on the right and then decide to put an amount in the middle that is intermediate between 1 and 9, we would pick 5. They would pick 3, because 1 times 1 is 3, and 3 times 3 is 9. It is logarithmic thinking rather than integral.
But we keep teaching toddlers to recite the sequence of numbers, and we think they understand them, but they don't. Then around 3 1/2, something clicks, and they get that 6 is 1 more than 5.
From that basic fact, arithmetic is possible, and all the math that follows.
It's a really cool show. I encourage y'all to go to their site and listen to it. I plan to work my way through their archives.
It also tells us it's silly to expect a toddler to understand integers. As parents we still have to count Cheerios with our kids, but we just can't expect them to get integers until they're ready, as with so much of child development.