If you hide your roomates' keys, you know they'll probably look where they last saw them. This knowledge is called "Theory of Mind" and it involves dissociating what you believe to be true from what other people may believe. For adults, it's incredibly easy.
But for the majority of three year olds, this is unfathomable. They will fail miserably on a test of Theory of Mind (called a false-belief task) while the majority of four year olds will succeed.
Leslie, German and Polizzi believe they have an answer. According to their February 05 paper in Cognitive Psychology, correct performance on false belief tasks requires overcoming a prepotent tendency to attribute "true" beliefs as the beliefs of everyone. The system that represents the beliefs and desires of others purportedly comes online at 2 years, and only then can children begin the lengthy process of learning about these "hidden" mental states. Successful performance requires inhibition of the default attribution, which is naturally that other people believe what is true. A generic "selection process" does the inhibiting that ultimately correctly attributes the false beliefs to others.
There are several complications to this theory of mind mechanism (ToMM) and selection process (SP), many of which they address in their paper:
1) If the representational ToMM system comes online at 2 years, why does it take 2 more years before the SP permits children to succeed at the false-belief task?
2) Why is the task made easier when you add the word "first" in front of the prediction question, as in "Where will Sally look first?
3) Why doesn't adding "first" help autistic children in the same way?
4) And why is it more difficult to correctly say where Sally will look than to say where Sally thinks it is, but only in "avoidance" false-belief tasks? (In avoidance versions, the object is aversive and Sally doesn't want to find it, and control tasks suggest kids can understand the statement semantically)
The authors argue that the "look first" comment (#2 above) helps in prediction questions because it makes the the first location more salient and thus more likely to be selected among competing representations by the executive selection process.
Leslie et al also posit that ToMM offers only plausible contents to SP, such that there are never more than two candidate beliefs: the last location of the bait to which the believer had access, and the current location of the bait. Usually the prepotent true belief "pathway" is selected as the belief of others by default - indeed, in most cases, people's beliefs are accurate. In the case of the avoidance task, Leslie et al. invoke the concept of "inhibition of inhibition" to explain question #4 above.
Philip Branning, a grad student in Randy O'Reilly's Computational Cognitive Neuroscience lab, has some concerns about the validity of the tasks described by Leslie et al. Since we're not always agreed on some of these points, we thought it would be a good opportunity to open up the floor for debate. Welcome, and let the games begin!