We also obtained an observed index of EC at T1 and T3. Persistence was recorded while children completed a puzzle that they could feel but not see. The puzzle was in a clear Plexiglas box with a cloth-covered front that had openings to allow children to reach inside. Children were able to cheat by lifting the cloth or viewing the puzzle through the Plexiglas. The experimenter told each child to “complete the task as fast as you can without looking at the puzzle” and then, before leaving the room, set a timer for 4 min so the child would know how much time was left. Persistence was the time working on the puzzle (vs. not working on it) without cheating divided by the total time spent on the puzzle (interrater rs < .95). This measure loads on latent constructs with adults’ reports of EC (Eisenberg et al., 2004; Valiente et al., 2003).
