Table 3.

Descriptions of Tests Assessing Social Skills

Skill	Test	Description	Scoring
Sharing	Dictator Game (Benenson, Pascoe, & Radmore, 2007)	Share stickers with classmates. Specifically, children first choose their 10 favorite stickers among a choice of 30. They are then told that, unfortunately, not enough stickers are available for all of their classmates. But participants could donate any number of their stickers to their classmates (the choice is made while the experimenter is looking away)	Number of stickers given (0–10)
Distributive justice	Resource allocation task (inspired from Huppert et al., 2018)	Distribute candies to characters in situations of inequality. Three situations are presented (resource inequality between a rich and a poor character, unequal contribution to a common good between a hard‐working and a lazy character, and a power inequality between a dominant and a subordinate character). At the end of each situation, children are told that both characters love candies and they have to distribute 4 candies to the characters the way they want	Number of candies allocated to the disadvantaged characters in each of the three conditions (0–4) and in total (0–12)
Social competence	Social Problem Solving Task‐Revised (object acquisition item; Rubin, 1988)	Solve a problem involving a social component. Two cartoon children are shown, one reading a book and the other standing behind him/her (characters gender matched the gender of the participants). Children are told that the character reading the book has been reading it for a very long time and that the other character wants to have the book. Participants have to imagine what the character could say or do to get the book, what else the character could say or do to get the book, and what they could themselves say or do if they want a book that another child is already using. The same story was used at each testing session	Number of responses with reference(s) to justice/sharing (0–3; Lillard, 2012), as well as the flexibility (i.e., level of novelty) of the second response in relation to the first response (0–3; Rubin & Clarke, 1983)
Theory of mind	Wellman and Liu (2004) task	Understand the mental state of a character. The task involves 5 stories measuring the complexity of theory of mind understanding (diverse desire, diverse belief, diverse knowledge, false belief, hidden emotion). The test is stopped after two failed stories	Number of stories completed successfully (0–5)

Scores were all consistent with preregistration, with two exceptions. In the dictator game, the number of stickers given was used rather than the number of stickers kept to be consistent with previous studies (Benenson et al., 2007). In the resource allocation task, the proportion of children who allocated the first candy to the disadvantaged characters was not included for the sake of parsimony.