Alix Spiegel at NPR

Why do some children who grow up in poverty do well, while others struggle?

To understand more about this, a group of psychologists recently did a study.

It began in a small spare room where a series of very poor mothers and their 5-month-old babies came to watch a soothing video. Soothing the baby was the point, says Elisabeth Conradt, a postdoctoral researcher at Brown University’s Brown Center for the Study of Children at Risk. The researchers needed to take measurements of the babies when they were calm.

On the screen, circles of gently colored shapes flickered and music softly played while a sensor taped to the baby’s chest recorded how much the baby’s heart beat when the baby breathed in, and how much the baby’s heart beat when it breathed out.

This simple measure has a complicated scientific name that sounds vaguely like a disease — baseline respiratory sinus arrhythmia — but the researchers were interested in it because it can tell you something about how a baby responds to the world around it.

You see, while there’s always a difference between how much the heart beats when a person inhales and when he or she exhales, everyone has a different set point. Sometimes there’s a big difference, and sometimes it’s small. And in very young babies, researchers have noticed that there are different temperaments associated with these different set points.

When there’s a big difference and the set point is high, babies tend to have great attention and can focus for long periods of time on the things in their environment. “When you’re presenting them with a new toy, they’re going to really look at it and inspect it,” says Conradt. “But they also may be more irritable and fussy when parts of their environment are changing.”

In contrast, babies with a low set point “might lose interest after a couple minutes, but they’re also not going to be as fussy or irritable,” she says.

Babies with a high set point seem to have a more sensitive nervous system, which makes them more sensitive to their environment, in both good and bad ways. Babies with a low set point seem to have a less sensitive nervous system, which makes them less sensitive to their environment.

Conradt and her colleagues wondered if this simple measure could be used to predict how children in poverty would fare as they aged…

Read on, the conclusions might surprise you.