Participants will complete the experiment online at [faceresearch.org][1] on their own computer. Participants will be randomly assigned to either kinship or similarity judgments. In the kinship condition, participants will be told: > In this experiment you will be shown 100 pairs of faces. Some are siblings, some are an unrelated pair. You will be asked to determine whether each pair is “unrelated” or “related”. After the experiment, you will be told how many of the 100 pairs you correctly determined and what the average performance on this task was. They will judge if each pair is related or not by clicking on buttons labelled "related" or "unrelated". [View kinship interface][2]. In the similarity condition, participants will be told: > In this experiment you will be shown 100 pairs of faces. You will be asked to rate each pair for similarity on a scale from 0 (not very similar) to 10 (very similar). They will judge the similarity of each pair on a 0 (not very similar) to 10 (very similar) scale. [View similarity interface][3]. At the end of the study participants will receive information about their accuracy and the average of those who already completed the study and will be debriefed about the aim to find the influence of sex and age difference on kin recognition. [1]: http://faceresearch.org/project?childfaces [2]: https://osf.io/d82tc/ [3]: https://osf.io/r75xx/