Our second prediction, that the model age-based bias would be most pronounced when social
information lacked evidence of efficacy and efficiency because the demonstrations would create the
most uncertainty, was not supported. Neither efficacy (demonstration completeness) nor efficiency
(irrelevant actions) affected the strength of the initial model-based bias toward child peers. The presence
of the model age-based bias, when both models gave demonstrations, varies from Wood et al.
(2015), who found that children did not distinguish between two peers who differed in previous proficiency
when two equally valid solutions were demonstrated. One explanation for this could be that
the age contrast in the current study may be considerably more salient than the peer proficiency
contrast in Wood et al. (2015) study. For the latter, the models differed in their general levels of proficiency,
as indexed by their behavior toward a novel apparatus as well as teacher ratings. This subtler
difference between models may have diluted children’s attention to proficiency in the context of the
test task. Indeed, the peer ratings of proficiency in Wood et al. (2015) were dominated by age, such
that children rated older peers as more proficient than younger peers irrespective of their actual proficiency.
Furthermore, previous work has shown that even though children can identify models who
‘‘know” versus ‘‘don’t know” how to do a task, their imitation of the model is driven more by their
age than by their professed knowledge state (Wood et al., 2012). An alternative explanation for the
current finding is that the preference for matching the child model, irrespective of demonstration content,
was driven by affiliative reasons rather than learning reasons (Uzgiris, 1981). If children copy to
affiliate, then it is of no consequence which method is more effective. Affiliative versus learning goals
may explain the discrepancy between the current study and Hu et al. (2013), who found that a bias
toward copying the majority was lost when children could see that both methods worked. This
‘‘second” function of imitation is receiving increasing attention (Over & Carpenter, 2012; Wood
et al., 2013b) and may be an important factor in children’s model-based social learning choices.