The Brain: What Do Babies Know?

What Sirois and his postgraduate assistant Iain Jackson are challenging is the interpretation of a variety of classic experiments begun in the mid-1980s in which babies were shown physical events that appeared to violate such basic concepts as gravity, solidity and contiguity. In one such experiment, by University of Illinois psychologist Renée Baillargeon, a hinged wooden panel appeared to pass right through a box. Baillargeon and M.I.T.'s Elizabeth Spelke found that babies as young as 31/2 months would reliably look longer at the impossible event than at the normal one. Their conclusion: babies have enough built-in knowledge to recognize that something is wrong.

Sirois does not take issue with the way these experiments were conducted. "The methods are correct and replicable," he says. "It's the interpretation that's the problem." In a critical review to be published in the forthcoming issue of the European Journal of Developmental Psychology, he and Jackson pour cold water over recent experiments that claim to have observed innate or precocious social cognition skills in infants. His own experiments indicate that a baby's fascination with physically impossible events merely reflects a response to stimuli that are novel. Data from the eye tracker and the measurement of the pupils (which widen in response to arousal or interest) show that impossible events involving familiar objects are no more interesting than possible events involving novel objects. In other words, when Daniel has seen the red train come out of the tunnel green a few times, he gets as bored as when it stays the same color. The mistake of previous research, says Sirois, has been to leap to the conclusion that infants can understand the concept of an impossibility from the mere fact that they are able to perceive some novelty in it. "The real explanation is boring," he says.

So how do babies bridge the gap between knowing squat and drawing triangles--a task Daniel's sister Lois, 2 1/2, is happily tackling as she waits for her brother? "Babies have to learn everything, but as Piaget was saying, they start with a few primitive reflexes that get things going," says Sirois. For example, hardwired in the brain is an instinct that draws a baby's eyes to a human face. From brain-imaging studies we also know that the brain has some sort of visual buffer that continues to represent objects after they have been removed--a lingering perception rather than conceptual understanding. So when babies encounter novel or unexpected events, Sirois explains, "there's a mismatch between the buffer and the information they're getting at that moment. And what you do when you've got a mismatch is you try to clear the buffer. And that takes attention." So learning, says Sirois, is essentially the laborious business of resolving mismatches. "The thing is, you can do a lot of it with this wet, sticky thing called a brain. It's a fantastic, statistical-learning machine." Daniel, exams ended, picks up a plastic tiger and, chewing thoughtfully upon its head, smiles as if to agree.