Investigations

Good intentions

With a series of simple experiments, Amanda Woodward asks the questions that get inside babies’ minds.

Consider the scene: your mother grabs a bowl, a cereal box, and a milk carton. Even before she pours, her intentions are clear: she’s making breakfast. While adult observers intuitively interpret such activity as goal-oriented, infants under 12 months are just beginning to understand the link between action and intention, and they learn to do so through their own experiences, according to Amanda Woodward, associate professor in Psychology, the Committee on Human Development, and the College.

Photo by Dan Dry Babies begin understanding intention in their first year, according to psychologist Amanda Woodward.

In a paper presented at the February meeting of the American Association for the Advancement of Science, Woodward, 39, counters two prevailing child-development theories: that babies are born with an innate system for interpreting intentions or that such a framework develops after 18 months, when children begin to talk. Instead, she argues, the first year contains many related milestones, as infants learn to recognize the goals that motivate grasping, looking, and simple multistep actions, such as opening a box to retrieve a toy.

“For that learning to take place,” explains Woodward, “babies have to understand that when other people act and move around, they’re not just robots moving mechanically through the world, but rather they are acting intentionally.” If babies observed movement without connecting it to a goal, “then all of the rich information that was present in their caretakers’ actions would be opaque to them.” It’s important, then, to ask when and how infants begin to understand others’ intentions.

In her research Woodward has created a new way to frame those questions. Because children under 12 months can’t respond verbally and don’t exhibit much coordinated behavior, “the trick,” she says, “is to figure out how to get inside their minds.” To that end she has adapted a developmental-psychology technique called the “visual habituation paradigm,” based on the theory that from birth babies can control how long they look at something, which reveals what they think is important. When they become bored with a scene they look away, but when a new element—a different movement or object—is introduced they look longer.

By measuring the time that babies spend eyeing a new element, Woodward can establish what they find significant, including intentional action. If an infant pays more attention to a change in the researcher’s motion (for example, reaching for the same toy from the left instead of the right) than a different object (using the same movement to grasp a new toy), she reasons, then the baby is placing more weight on the action than the goal. If the same movement but a different toy elicits more attention, then the infant is focused not on the physical motion but the intention behind it.

In a tiny, makeshift booth in her Beecher Hall lab, 6-month-olds watched one of Woodward’s student assistants grasping a ball. When the babies became sufficiently bored with that action the student changed tactics, either making the same movements to grasp a bear or a different motion to pick up the ball. Overall, the babies were most intrigued when the assistant grabbed the bear than by the shift in movement. Because the infants found a new goal more interesting, Woodward concluded that by 6 months, babies can understand the intention motivating an adult’s grasp.

But grabbing is a straightforward activity. More complex acts like looking—which creates an invisible connection between observer and object—or retrieving a toy from a closed box—a sequence of steps toward a single goal—can confound young infants. Using a similar setup, Woodward showed that babies begin to recognize the actions’ underlying intentions only near the end of the first year.

This knowledge, Woodward realized, develops at about the same time that infants themselves start to make similarly conceptual actions. Pointing, for example, expresses only a cognitive connection between observer and object, and “if you point for a little baby,” explains Woodward, “they do what your dog does; they stare at your hand.” But older infants, who themselves are pointers, will follow a point. Likewise, babies who can produce goal-directed, multistep actions—like pulling a cloth to move a toy closer— understand when they witness simple sequences.

Such correlations, she says, “raised the question of whether learning to produce an action actually changes how babies think about that action when somebody else produces it.” To find the causal link, Woodward had to do an “experimental intervention”— changing the acts that her subjects could perform.

To see if agency—in this case, the ability to grab an object—changes how babies understand an action, Woodward outfitted 3-month-olds with specially made Velcro mittens and placed Velcro-coated toys in front of them. When you place an object before a younger infant, she explains, “what you get is often a lot of staring at the object—you might get muscle tension, and you’ll get some flapping, but what you won’t get is smooth and coordinated reaching” and grasping. In this experiment, when the babies “flapped” around and accidentally hit the toy, it stuck to their hand and they were able to move it. Very quickly, she says, the infants began to act purposefully to “grab” the toys.

Later the same babies and an unmittened control group were shown a mittened student assistant reaching for the Velcro toys. The babies who had used the mittens paid more attention when the toy was changed than to a new motion, while the control group focused on the assistant’s movement. “This is the first piece of evidence that I know of,” Woodward says, “that infants’ own experience as an intentional agent actually provides direct information for them to interpret the action of other people.”

In the coming months Woodward’s lab will continue to study how babies use their experiences to learn about intention and how they organize that information. She is also embarking on a project to see if infants’ results in her intentional-agent experiments will predict their level of abstract thinking some three years later. For this, Woodward says, she’ll have to track down the kids and do more “cognitive detective work” to solve another developmental puzzle.—A.L.M.