In this study, we set out to extend our knowledge of 4- to 6-year-old children’s flexible use of social
learning strategies by manipulating observer certainty in the efficacy and efficiency of differently aged
models. The study employed a puzzle box, the ‘‘Slotbox,” which was designed so that each of two functionally different tools could be used to extract a soft toy. Given mixed findings regarding the
direction of model biases for age, we did not make a prediction in this respect. Rather, we aimed to
explore the effects of uncertainty on such a bias occurring in either direction. Uncertainty about the
efficacy of the social information was created by varying the completeness of the demonstrations such
that whereas some children saw both models complete all of the necessary series of actions involved
and have a token extracted, others saw a degraded, less complete series of these actions that did not
reveal eventual successful removal of the token from a puzzle box task. Uncertainty about the effi-
ciency of the social information was created by varying whether models incorporated visibly causally
irrelevant, and thus inefficient, actions into their demonstrations. A final group of children did not witness
any social information