When it comes to children, most parents are usually hyper-alert to threats, from uncovered electrical sockets to the neighbor's dog. Yet in low-risk situations, when a child is, say, strapped safely into the back seat, they rely less on parental anxiety to carry them through than on working memory, the short list of thoughts and duties stored for easy access.
But it turns out that working memory is smaller and more fragile than is often assumed, said Nelson Cowan, a psychologist at the University of Missouri in Columbia who studies memory capacity.
Many of us can remember more than a half-dozen items at a time, for example, if they are related things, such as meetings or appointments scheduled throughout a workday, he said. But if the thoughts are unrelated, such as child care and work duties, then our heads usually hold only three to five things, Cowan has found. "For many people, child care falls into the 'home' category and work falls under 'work,' and there's no overlap at all," Cowan said. "The two are unconnected and competing for attention."
In people of all ages, but especially those middle-aged and older, that competition can knock important thoughts or duties out of the ring. As anyone who has gone to the store without a written shopping list knows, the very act of remembering one thing on the list can immediately erase all the others, at least momentarily. "You think 'bread' and then you stroll down the bread aisle and now you're distracted by all the different brands, and suddenly you're at a loss -- you can't remember any of the other things on the list."
It doesn't matter as much as we think that a child is far more important than a loaf of bread, psychologists say. In working memory, the two very different thoughts -- check on the baby, look for sourdough -- are still vying for limited space.
"The fact is that for most of us it is hard to hold onto even one thought," said Michael Kane of the University of North Carolina at Greensboro, who studies distraction and working memory. In a series of experiments, Kane and Randall Engle of the Georgia Institute of Technology have shown that a flashing light on a computer screen is enough to confuse college students trying to accomplish a very simple task, such as turning their head away from the light.
The critical importance of remembering to pick up or care for a child can actually betray our better instincts to be vigilant, say memory researchers. "People think, 'There's no way I'm going to forget to pick up my own child,' so they don't worry about it enough," Cowan said.
