Being a parent means being always on edge, always vigilant. That's why so many were dumbfounded to hear reports recently that a UC Irvine professor had driven to work and forgotten to take his 10-month-old son out of the car. The boy later died of heat exposure, as have at least three other young children left unattended in cars in the West this summer.
How does a decent, responsible person neglect the most important thing in his or her life? You can count the ways, say experts on memory and human error.
"Any parent who looks at these cases and thinks, 'I'm confident that could never happen to me,' should stop and think again," said Todd Braver, a neuroscientist at Washington University in St. Louis who studies memory.
About 30 children die each year of heat exposure in the United States after being left unattended in hot cars, experts estimate. In just the past two months, two boys, ages 3 and 5, died after being left for five hours in an SUV near Lancaster; and a 7-month-old left in a hot van in Las Vegas died after his dad forgot to drop him off at the baby sitter's. Many more are left by accident in stores, at home or, in one 1987 case, in a car seat placed on top of the car; the mother drove two blocks before her 2-month-old fell off, injuring his collarbone. While some of these mishaps are due to neglect or resentment, experts say that most are tragic blunders by otherwise responsible parents.
"These kinds of errors are made all the time, and for most of us we're just fortunate the consequences aren't so tragic," Braver said.
For years, psychologists and other neuroscientists have searched for common denominators in cases of serious human error. They have done laboratory experiments on distraction. They have had people keep detailed diaries of their memory lapses. And they have tried to recreate the precise circumstances and thinking (or lack thereof) at the time.
The evidence suggests that people make awful, life-changing mistakes for the same reasons they forget to pick up the milk: because they misjudge the reliability of their own memory; because they're highly distractible; and because they're generally unaware of how easily and completely they can become engrossed in pet projects or problems, absent to everything else.
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.