Parents tell a million little white lies a day: “If you keep making that face, it’ll freeze that way,” “We’re almost there!” Studies have confirmed that children can often tell when adults are lying to them. In a new study, researchers from MIT set out to understand a subtler distinction: Can children recognize when adults are telling the truth, but not the whole truth? 

Laura Schulz, associate professor of cognitive science, and Hyowon Gweon, an MIT postdoc, explain that learning how to perceive “sins of omission” is an important skill for children to develop—part of figuring out whom they can trust and whom they need to avoid. They determined that children can distinguish between incomplete and complete truth, and that they also compensate for incomplete information by trying to figure things out on their own. 

The study divided six- and seven-year-old children into two groups. One group was given a toy with had four buttons, each of which activated a different feature: a windup mechanism, LED lights, a spinning globe, and music. The second group had a toy that looked identical, but in fact possessed only one feature—the windup mechanism. Both groups watched a teacher’s demonstration of the toy that explained only the windup feature. Asked to rate the helpfulness of the teacher on a scale from 1 to 20, the children who suspected their toy had more undemonstrated features gave the teacher much lower ratings than the children who believed the windup feature was the toy’s only function. The children who knew their toy had four features also explored the toy much more extensively than the children who perceived the teacher’s demonstration to be complete. In other words, omitted knowledge awakened the children to the existence of ignorance—including their own—leading the children to be much more inquisitive. 

This recent study built off a 2011 project in which Schulz and Gweon investigated how a demonstration affected children’s play. When a teacher explained one feature of a toy—that it squeaks when a yellow tube is pulled—and disregarded the toy’s other features, the children spent most of their time exploring only the feature the teacher had demonstrated. By contrast, children who received no instruction spent more time trying to figure out the toy’s multiple features. Explicit instruction, rather than igniting a child’s interest, can dampen a child’s inclination to explore, according to this research. Instruction and exploration aren’t always at odds, but teachers and parents should negotiate the balance, it seems. 

In an upcoming paper, to be delivered at the annual conference of the Cognitive Science Society in July, Schulz and Gweon will explore the flip-side of this problem: how children react to too much information. They found that children prefer teachers who do not spend time offering information that they already know—or that they can infer from what they already know. It’s not that children hate know-it-all’s, but they do make calculations in order to learn more efficiently, say Schulz and Gweon. Learning, they conclude, isn’t just about acquiring knowledge of the world; it’s also about learning how to learn.

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