Selective copying of the majority suggests children are broadly “optimal- ” rather than “over- ” imitators

Human children, in contrast to other species, are frequently cast as prolific“over- imitators”. However, previous studies of “over- imitation” have overlooked manyimportant real- world social dynamics, and may thus provide an inaccurate account ofthis seemingly puzzling and potentially maladaptive phenomenon. Here we investigatethis topic using a cultural evolutionary approach, focusing particularly on the keyadaptive learning strategy of majority- biased copying. Most “over- imitation” researchhas been conducted using consistent demonstrations to the observer, but wesystematically varied the frequency of demonstrators that 4- to 6- year- old childrenobserved performing a causally irrelevant action. Children who “over- imitate” inflexiblyshould copy the majority regardless of whether the majority solution omits or includesa causally irrelevant action. However, we found that children calibrated their tendencyto acquire the majority behavior, such that copying did not extend to majorities thatperformed irrelevant actions. These results are consistent with a highly functional,adaptive integration of social and causal information, rather than explanations implyingunselective copying or causal misunderstanding. This suggests that our species mightbe better characterized as broadly “optimal- ” rather than“over-” imitators