Do Women Have an Evolved Preference for Pink?

Short answer, no. Duh. Long answer, man do I hate how psychology gets reported in the media. If you were surfing around news sites earlier this week, you might have come across something like this:

A study in Current Biology reports some of the first conclusive evidence in support of the long-held notion that men and women differ when it comes to their favorite colors. Indeed, the researchers found that women really do prefer pink--or at least a redder shade of blue--than men do.

Which quickly turned into this:

Girls Really Do Prefer Pink

The attraction may owe to evolutionary influences, researchers say

Ugh. You don't even have to read the journal article (a letter, actually) to know that there's something fishy there, but let's go through the study by Hulbert and Ling(1) anyway.

The experiment is as simple as they come. Two-hundred eight participants, including 110 females (92 British and 18 Han Chinese) and 98 males (79 British and 19 Han Chinese) looked at pairs of rectangular color patches (each representing one of 8 base colors) and indicated witch of the pair they preferred. Hulbert and Ling then took all of those preference ratings and converted them to proportions, so that the score for each color was the proportion of trials on which it was preferred. That gives you graphs that look like this (p. R624):

Those colors, just so you know, are only approximations of the actual colors used. And why did they use a line graph; they only used 8 discrete colors, right? Oh, because using a line graph makes it look like they measured the whole spectrum, which would make their study about three-hundred times better. Moving on, though, and pretending their stimuli were continuous for the sake of argument, the graphs should be pretty clear: the women's preference curves jump up over 50% (meaning they preferred the particular color in more than half its comparisons) further to the reddish end of the (cough) spectrum, and drops off closer to the blue, middle of the spectrum than the males. That trend is present in both the graph for the British subjects and that for the Chinese subjects, though it's much less pronounced in the latter.

Confirming this interpretation through principle component analysis, Hulbert and Ling found that two components, corresponding to the red-green and blue-yellow opponent contrasts that are inherent in the way our cones represent color, account for the most variance in the data. For all subjects males and females preferred blueish colors to yellowish ones on the yellow-blue opponent-contrast dimension, and for the British subjects, the females showed a significantly stronger preference for blue vs. yellow. On the red-green opponent-contrast dimension, the British males show a fairly strong preference for the greenish side of the contrast, while the Chinese men show no preference. The Chinese women, on the other hand, show a fairly strong preference for the reddish side of the contrast, while the British women show no real preference.

Interpretations? Both men and women like blueish colors more than yellowish ones, while only Chinese women prefer reddish ones to greenish (while British men seem to dig the greenish colors). What does this mean? Here's what Hulbert and Ling conclude:

[W]hile both males and females share a natural preferencefor 'bluish' contrasts, the female preference for 'reddish' contrasts further shifts her peak towards the reddish region of the hue circle: girls' preference for pink may have evolved on top of a natural, universal preference for blue. We speculate that this sex difference arose from sex specific functional specializations in the evolutionary division of labour. The hunter- gatherer theory proposes that female brains should be specialized for gathering-related tasks and is supported by studies of visual spatial abilities [7]. Trichromacy and the L-M opponent channel are 'modern' adaptations in primate evolution thought to have evolved to facilitate the identification of ripe, yellow fruit or edible red leaves embedded in green foliage [8]. It is therefore plausible that, in specializing for gathering, the female brain honed the trichromatic adaptations,
and these underpin the female preference for objects 'redder' than the background. (R624-R625)

Not inconsistent with this... story, is an earlier finding by Bimler et al. that women are better at making distinctions on the red-green dimension. Bimler et al.(2) gave participants three colors at a time, and asked them to selected the color that didn't go with the other two. Using this task you can figure out how good people are at discriminating colors by looking at the distance (on the color spectrum) they need to distinguish between two colors (and thus pick one of the two out as the one that doesn't belong). And for colors on the red-green axis, their female participants were better discriminators than the males.

In a sense, then, it seems as though women might just have better color vision than men, a hypothesis further supported by the fact that the vast majority of individuals with color blindness are male, with the majority of those being red-green color blind in some way. This could be a result of women's role as gatherers back in the Pleistocene, or it could be a result of the fact that the genes responsible for color vision seem to be on the X chromosome. Who knows? I suppose it doesn't bode well for the women-as-gatherers hypothesis that they prefer blue to yellow (with the British females actually preferring it more than the British males), what with their needing to find the yellow fruit and all.

But what's really tough for the women-as-gatherers hypothesis is the fact that the largest portion of Hulbert and Ling's female sample, the British women, don't actually show a significant preference for reddish colors over greenish ones. They show no preference on that dimension. Perhaps British women are particularly bad at finding red, edible leaves among all the green ones, while Chinese women are OK at it? Or maybe the purely speculative women-as-gatherers story is bullshit. I'll let you decide.

Suffice it to say that this result doesn't tell us anything about why girls like pink. In fact, since, at least in western culture, the traditional gender-color associations are blue for boys and pink for girls, the fact that the western (British) girls prefer blue more than the western boys (and, in fact, show a stronger preference for blue over yellow than red over green) in the Hulbert and Ling study implies that, biologically, either blue should be for girls, or there should be no gender-based assocation with blue. Furthermore, the British women don't show any preference on the red-green dimension! You'd think, if they had an evolved preference for pinkish colors, they'd actually show such a preference, but they don't. Then there's the cross-cultural differences for men. It's as though the British men are saying, "Ewww, reddish colors are for giiiiiiirls," and picking the greens, while the Chinese men just don't care on that dimension, because they don't associate red with girlishness. In other words, it's almost as though there were cultural factors at play!

¹Hulbert, A.C., & Ling, Y. (2007). Biological components of sex differences in color preference. Current Biology, 17(16), R623-R625.
²Bimler, D.L., Kirkland, J., & Jameson, K.A. (2004). Quantifying variations in personal color spaces: Are there sex differences in color vision? Color Research and Application, 29(2), 128-134.