Interpreting digit ratio (2D:4D)-behavior correlations: 2D:4D sex difference, stability, and behavioral correlates and their replicability in young children.

The popularity of using the ratio of the second to the fourth digit (2D:4D) to study influences of early androgen exposure on human behavior relies, in part, on a report that the ratio is sex-dimorphic and stable from age 2 years (Manning etal., 1998). However, subsequent research has rarely replicated this finding. Moreover, although 2D:4D has been correlated with many behaviors, these correlations are often inconsistent. Young children's 2D:4D-behavior correlations may be more consistent than those of older individuals, because young children have experienced fewer postnatal influences. To evaluate the usefulness of 2D:4D as a biomarker of prenatal androgen exposure in studies of 2D:4D-behavior correlations, we assessed its sex difference, temporal stability, and behavioral correlates over a 6- to 8-month period in 126, 2- to 3-year-old children, providing a rare same-sample replicability test. We found a moderate sex difference on both hands and high temporal stability. However, between-sex overlap and within-sex variability were also large. Only 3 of 24 correlations with sex-typed behaviors-scores on the Preschool Activities Inventory (PSAI), preference for a boy-typical toy, preference for a girl-typical toy, were significant and in the predicted direction, all of which involved the PSAI, partially confirming findings from another study. Correlation coefficients were larger for behaviors that showed larger sex differences. But, as in older samples, the overall pattern showed inconsistency across time, sex, and hand. Therefore, although sex-dimorphic and stable, 2D:4D-behavior correlations are no more consistent for young children than for older samples. Theoretical and methodological implications are discussed.

Preferences for Pink and Blue: The Development of Color Preferences as a Distinct Gender-Typed Behavior in Toddlers.

Many gender differences are thought to result from interactions between inborn factors and sociocognitive processes that occur after birth. There is controversy, however, over the causes of gender-typed preferences for the colors pink and blue, with some viewing these preferences as arising solely from sociocognitive processes of gender development. We evaluated preferences for gender-typed colors, and compared them to gender-typed toy and activity preferences in 126 toddlers on two occasions separated by 6-8 months (at Time 1, M = 29 months; range 20-40). Color preferences were assessed using color cards and neutral toys in gender-typed colors. Gender-typed toy and activity preferences were assessed using a parent-report questionnaire, the Preschool Activities Inventory. Color preferences were also assessed for the toddlers' parents using color cards. A gender difference in color preferences was present between 2 and 3 years of age and strengthened near the third birthday, at which time it was large (d > 1). In contrast to their parents, toddlers' gender-typed color preferences were stronger and unstable. Gender-typed color preferences also appeared to establish later and were less stable than gender-typed toy and activity preferences. Gender-typed color preferences were largely uncorrelated with gender-typed toy and activity preferences. These results suggest that the factors influencing gender-typed color preferences and gender-typed toy and activity preferences differ in some respects. Our findings suggest that sociocognitive influences and play with gender-typed toys that happen to be made in gender-typed colors contribute to toddlers' gender-typed color preferences.

Effects of Gender Color-Coding on Toddlers' Gender-Typical Toy Play.

Gender color-coding of children's toys may make certain toys more appealing or less appealing to a given gender. We observed toddlers playing with two gender-typical toys (a train, a doll), once in gender-typical colors and once in gender-atypical colors. Assessments occurred twice, at 20-40 months of age and at 26-47 months of age. A Sex × Time × Toy × Color ANOVA showed expected interactions between Sex and Toy and Sex and Color. Boys played more with the train than girls did and girls played more with the doll and with pink toys than boys did. The Sex × Toy × Color interaction was not significant, but, at both time points, boys and girls combined played more with the gender-atypical toy when its color was typical for their sex than when it was not. This effect appeared to be caused largely by boys' preference for, or avoidance of, the doll and by the use of pink. Also, at both time points, gender differences in toy preferences were larger in the gender-typical than in the gender-atypical color condition. At Time 2, these gender differences were present only in the gender-typical color condition. Overall, the results suggest that, once acquired, gender-typical color preferences begin to influence toy preferences, especially those for gender-atypical toys and particularly in boys. They thus could enlarge differences between boys' and girls' toy preferences. Because boys' and girls' toys elicit different activities, removing the gender color-coding of toys could encourage more equal learning opportunities.

Are there parental socialization effects on the sex-typed behavior of individuals with congenital adrenal hyperplasia?

Influences of prenatal androgen exposure on human sex-typical behavior have been established largely through studies of individuals with congenital adrenal hyperplasia (CAH). However, evidence that addresses the potential confounding influence of parental socialization is limited. Parental socialization and its relationship to sex-typical toy play and spatial ability were investigated in two samples involving 137 individuals with CAH and 107 healthy controls. Females with CAH showed more boy-typical toy play and better targeting performance than control females, but did not differ in mental rotations performance. Males with CAH showed worse mental rotations performance than control males, but did not differ in sex-typical toy play or targeting. Reported parental encouragement of girl-typical toy play correlated with girl-typical toy play in all four groups. Moreover, parents reported encouraging less girl-typical, and more boy-typical, toy play in females with CAH than in control females and this reported encouragement partially mediated the relationship between CAH status and sex-typical toy play. Other evidence suggests that the reported parental encouragement of sex-atypical toy play in girls with CAH may be a response to the girls' preferences for boys' toys. Nevertheless, this encouragement could further increase boy-typical behavior in girls with CAH. In contrast to the results for toy play, we found no differential parental socialization for spatial activities and little evidence linking parental socialization to spatial ability. Overall, evidence suggests that prenatal androgen exposure and parental socialization both contribute to sex-typical toy play.

The space-math link in preschool boys and girls: Importance of mental transformation, targeting accuracy, and spatial anxiety.

Spatial abilities are pertinent to mathematical competence, but evidence of the space-math link has largely been confined to older samples and intrinsic spatial abilities (e.g., mental transformation). The roles of gender and affective factors are also unclear. This study examined the correlations between counting ability, mental transformation, and targeting accuracy in 182 Hong Kong preschoolers, and whether these relationships were weaker at higher spatial anxiety levels. Both spatial abilities related with counting similarly for boys and girls. Targeting accuracy also mediated the male advantage in counting. Interestingly, spatial anxiety moderated the space-math links, but differently for boys and girls. For boys, spatial abilities were irrelevant to counting at high anxiety levels; for girls, the role of anxiety on the space-math link is less clear. Results extend the evidence base of the space-math link to include an extrinsic spatial ability (targeting accuracy) and have implications for intervention programmes. Statement of contribution What is already known on this subject? Much evidence of a space-math link in adolescent and adult samples and for intrinsic spatial abilities. What does this study add? Extended the space-math link to include both intrinsic and extrinsic spatial abilities in a preschool sample. Showed how spatial anxiety moderated the space-math link differently for boys and girls.