We've all had this experience: we step into a familiar room, hit a wall switch, and... nothing happens. We're left to decide among a number of possibilities, like whether we've hit the wrong switch, whether a light bulb has burned out, or whether there's nothing plugged into the outlet it operates. All of them are reasonable possibilities, and it's left to us to make inferences about which of them makes the most sense. Did we do something wrong, or is something broken? A short paper in today's issue of Science indicates that toddlers face these same sorts of questions, and are able to make statistical inferences when trying to answer them.

The study involved two experiments performed with 83 toddlers, focused on the operation of toys. In the first, the researchers had three toys that were identical except in terms of color. The researcher pressed a button on a green one, which triggered a short bit of music. Either the same green toy or a yellow one were then handed to the toddler, while the red one was placed a short distance away; in either case, when the child pressed the same button, nothing happened, leaving them faced with the question of whether the issue was them (operator error) or the toy.

When handed the green one, which had just played music, they tended to assume it was them. About two-thirds of these toddlers changed the operator by handing the toy to their parents. In contrast, when given the yellow one, they assumed the toy was broken; 80 percent of them reached for the red toy, presumably because they felt it would be a working replacement.

The researchers recognized that there are other possible interpretations, such as the toddlers expecting that their parents could fix the apparently broken toy and hand it back. So, they devised another experiment to control for that. In the second one, toddlers tended to exchange the toy if it had only worked half the time a researcher pressed the button, even if the researcher had been switched half-way through the experiment (about 2/3 of the toddlers reached for an alternative toy). But, if the toy worked consistently for one researcher and always failed when another tried to operate it, the toddlers decided it must be an operator problem and handed the toy to their parents.

The numbers in each trial are a bit small (around 20 toddlers per condition), but the trends seem pretty clear: even very young kids have a sense of when something has gone wrong that's beyond their control, and can differentiate between that and a situation where something is apparently beyond their abilities. They're even able to track simple statistical patterns in order to do so. Thus, the authors conclude that when faced with failure, kids know how to answer the question "Is it me or the world?"

Science, 2011. DOI: 10.1126/science.1204493 (About DOIs).