Pink and Blue
Gerianne M. Alexander's 2003 review suggests that there may be evolutionary reasons why girls prefer some toys and boys prefer others. She suggests that there may be innate visual biases that draw children to specific features of the toys, including color:
The traditional assumption has been that children's associations of color with sex role is a socialization artifact. Picariello et al's (1990) experiments seem to show that children as young as 3 identify colors with sex roles. Children were asked to identify the sex of toy pigs who differed only in color, and their choices were consistent with adult sex-color stereotypes.
So the hypothesis, as far as I can tell, is not that boys like blue, but that girls really like pink. I find Alexander's (2002) study of toy preferences among vervet monkeys interesting, but I question the interpretation of results. I'm fairly certain that a vervet monkey doesn't know what a cooking pot is for. Therefore, the result that more female vervets initiated contact with the pot than with the ball seems like an over extension to me. If there were other features of the pot to explain this (color or decoration) these were not explained in the article.
[edit]: According to Color Matters, pink was traditionally for boys and blue for girls through the 1920's, and in Belgium, this is still the case.
Compared to boys, girls are also more likely to use a greater number of colors and to prefer warmer colors (i.e., pink and red) to cooler colors (i.e., blue and green). In toy choices and free drawings, then, boys appear to assign greater attention or interest to object movement and location, whereas girls appear to assign greater attention or interest to form and color."Suggested explanations for this greater female emphasis on color include aid in foraging, spectral qualities of the human face (apparently males tend to have redder faces), or the idea that infant faces are more red-pink than adult faces.
The traditional assumption has been that children's associations of color with sex role is a socialization artifact. Picariello et al's (1990) experiments seem to show that children as young as 3 identify colors with sex roles. Children were asked to identify the sex of toy pigs who differed only in color, and their choices were consistent with adult sex-color stereotypes.
So the hypothesis, as far as I can tell, is not that boys like blue, but that girls really like pink. I find Alexander's (2002) study of toy preferences among vervet monkeys interesting, but I question the interpretation of results. I'm fairly certain that a vervet monkey doesn't know what a cooking pot is for. Therefore, the result that more female vervets initiated contact with the pot than with the ball seems like an over extension to me. If there were other features of the pot to explain this (color or decoration) these were not explained in the article.
[edit]: According to Color Matters, pink was traditionally for boys and blue for girls through the 1920's, and in Belgium, this is still the case.