Young children's spontaneous inspection of negative instances in a search task.

Forty children 1 1/2 to 3 1/2 years of age searched for stickers that were hidden underneath two discretely different classes of objects embedded in arrays containing several classes. The paper focuses on a previously unobserved strategy that appeared at 3 1/2. Whereas the younger children searched underneath those objects that looked like the objects the children knew had stickers, the 3 1/2-year-olds systematically explored not only the objects that did, but also the objects that did not, have stickers. Eight adults performed similarly to the 3 1/2-year-olds. Analyses of developmental trends in the data and the observation of individual children performing the tasks suggest that the children's increased inspection of the negative objects was not merely the result of a random or more exhaustive search. The children appear to have been attempting to determine which kinds of choices were the wrong ones. The attempt to define and delimit negative cases is a central aspect of reflective thought.