We are replicating Maloney & Dal Martello (2006, JoV) with a larger number of face pairs (100) and raters (200) to determine whether age and sex differences influence similarity and/or relatedness judgments of child siblings.
While this original study (using 30 pairs of child faces with 64 raters) found no evidence for an influence of age or sex differences in similarity or relatedness judgments, DeBruine et al (2009, Vis Res) found evidence for an effect of sex differences in adult sibling faces.
1. Similarity and kinship judgments are linearly related.
2. Thresholded similarity judgments do not provide identical information to kinship judgments.
3. Sex differences negatively influence similarity, but not kinship judgments.
4. Age differences negatively influence similarity, but not kinship judgments.