The curse of knowledge: Mistaking your beliefs for those of others
scienceblogs.com
scienceblogs.com
Do we not ask:
"Where did I put my keys!?"
and not:
"What did I put my keys, on, in, above, or below?!"
More adults answered 'box' and in reality I think what 'Sally' would do would be very dependent on the exact placement and the path she takes into the room, and her order of perceiving the containers. If she takes in the whole scene before deciding where to go/look, the box; if she moves to the expected place and then is surprised by the difference, the bucket. (This question in its first form may really be testing whether the answerer is primarily visual or kinesthetic in their modelling of other people.)
But still, the essential point is the difference when people are told where the ball really is. 'Sally' still does not know, so a rigorously logical answer would be the same as the first case. (The additional information is irrelevant for predicting Sally's actions.) And yet, the additional information does cause a statistically significant difference in chosen answers.
That means the answerer's mind, or model of mind, is leaky. Once 'primed' with info, they can't pretend they don't know it, or model the mind of someone who doesn't know it.
Note in this case 'leaky' doesn't mean 'worse' (even though it is more like the younger child's answers). A straightforward policy of hewing to what is true regardless of what others know or how the knowledge was acquired is fine; it just isn't ideal for some social roles -- like lawyer or poker player -- that require a detailed understanding of others' limited information.
So the real pro predictor, when asked "Where does Sally look first?", might ask in response: "How old is Sally? Does she more often pretend-play to be an athlete or a detective? What are her parents' careers?"
If one knows that the ball is in the bucket this reinforces the concept that balls go in buckets or reminds one that more often than not people put balls in buckets.
Similar to the way that lots of people pick the same number in a given range or pick the same fruit when asked, etc., the most likely container for people to pick may be a bucket. People could be responding to an innate understanding of this fact; possibly without realising it.
Speculation, but still a decent logical explanation IMO.
A pre-experiment should be performed by asking people which vessel a ball should be placed in; the experiment in question could then choose only vessels with matching preference as ball receptacles as the options.
But that wasn't one of the options, apparently. I'm not trying to be funny; that really is my "best guess" as to the resulting behavior. The question itself brings in the hidden assumption that Sally will see her only choices as "look for the ball in one of four places" and in the real world the situation is much less constrained; running to Mommy is likely to result.
I'm not complaining about the hidden assumption, either; all such hypothetical questions bring in hidden assumptions, and it's fair to use them here.