Integration of thought and action continued: Scale errors and categorization in toddlers.

To further explore the effect of weighted arms on toddler's performance in problem solving (Arterberry et al., 2018, Infancy, 23(2), 173), the present study explored scale errors and categorization, two instances where infants appear to show more advanced knowledge than toddlers. Experiment 1 (N = 67) used a novel task for inducing scale errors among 24- to 29-month-olds. Results replicated rates of scale errors found in previous research that used different tasks. Experiment 2 used sequential touching (N = 31) and sorting measures (N = 23) to test categorization in 24-month-old children. In both measures, children showed categorization at the basic level when there was high contrast between the exemplars, but not at a basic level with low contrast or a subordinate level. In Experiments 1 and 2, half the participants were tested while wearing weighted wristbands. Weighting the arms did not affect error rates, in contrast to previous research showing that weights improved performance in search tasks. The findings are discussed in light of children's difficulty in integrating perception, cognition, and action.