precision, and clarity. Although this may reflect a naturally occurring difference in competence, it was
important to avoid confounding an age bias with a competence bias. Thus, as in Wood et al. (2012), the
video demonstrations focused on the task, showing just the model’s hands and unclothed arms, and
were performed by adults. The ‘‘child” demonstration was modeled by a 20-year-old who had small,
child-like hands, and the adult demonstration was modeled by a 21-year-old who had average-sized
hands, with only the hands and lower arms being visible in the video presentations. No hands had jewelry,
nail varnish, or overtly manicured nails. Copies of these video demonstrations are available in the
online Supplementary material. In Wood et al. (2012), 20 adults, blind to the study, did not notice that
adult and child demonstrations were both performed by adults. In the current study, no child said that
the demonstrations were not performed by the model.