Thursday, 23 August 2007

Blue vs. pink

There's a study by Anya Hurlbert and Yazhu Ling in the latest issue of Current Biology (volume 17, No. 16, p. R623) that purports to show that women prefer the colour pink compared to men. The authors explained this as a result of hunter/gatherer era distribution of labour. Women did the gathering and thus needed to pick out red berries from a green background, while the men were out killing stuff. This was picked up widely in the media (for example, there's a Times article here). As you might imagine, it has also caused some controversy, with the Grauniad's Zoe Williams imploring us to 'Stop this idiocy now!'. Nonetheless, I don't get the impression that anyone has actually read the paper. There certainly appears to be no considered evaluation of the research methods employed in the study in Williams's diatribe. So, using my academic ninja skills, I looked up the paper and read it. I recommend this approach to any science journalists.

The research methodology of the paper seems to be sound. Essentially, the authors of the study got a group of men and a group of women, a total of 208 people. The subjects "used a mouse cursor to select, as rapidly as possible, their preferred color from each of a series of pairs of small colored rectangles presented sequentially in the center of an otherwise neutral CRT display." The results were quite striking, with women clearly having a preference for pink hues with respect to men. Interestingly, the differences for a Han Chinese sub-group were much less pronounced. Anyway, so far so good. Conclusion: Women like pink hues more than men do.

So why do women prefer pink? The authors write 'We speculate [my emphasis] that this sex difference arose from sex specific functional specializations in the evolutionary division of labour'. They go on to propose that the difference might relate to women gathering red berries, or the need for women to notice subtle changes in skin colour in 'their roles as care-givers and empathizers'. As evidence for this speculation, the authors employ something called the Bem Sex Role Inventory, showing that masculinity and femininity correlate with colour preference. What on Earth is the Bem Sex Role Inventory? It turns out that this works by asking the subject how they rate themselves against a list of 60 adjectives. 20 of the adjectives are 'desirable for men' (e.g. assertive, independent, analytical), 20 are 'desirable for women' (e.g. loyal, warm, shy) and 20 are 'gender neutral' (e.g. happy, tactful, jealous). People are asked to rate themselves for each adjective on a 7-point scale. Clearly, as scientific methodology this leaves a lot to be desired, and it seems to me that this is just testing cultural constructions of masculinity and femininity. I'm not convinced that it backs the authors speculation that innate biological factors account for sex differences in colour preference. In fact, the authors are quite careful about this, and state that 'while these differences may be innate, they may also be modulated by cultural context or individual experience. In China, red is the color of ‘good luck’, and our Chinese subpopulation gives stronger weighting for reddish colors than the British'. This doesn't seem to be reflected in any of the media stories about the research, which is what happens when you get reporting by press release. Anyway, in my opinion, the research can't distinguish between innate and cultural explanations of the observations, and the stronger preference for red hues among the Chinese subjects certainly seems to suggest that cultural factors are important.

So, what have we learned? Well, we've learned that women prefer pink hues in comparison to men. But I don't think we've learned why. So, when Williams says 'Humanity has nothing to gain from research into whether females prefer the colour pink', is she right? I don't think so. We've learned something, and for that reason alone I think the research is valuable. And if we can say something definite about the reasons for the differences found in the paper, we can say something about our society and why it works in the way it does.


Lauredhel said...

I tried to do a little source-chasing on just one of the assertions from their introduction ("the prevalence and longevity of the notion that little girls differ from boys in preferring 'pink'"), and it completely failed to pan out - the assertion was unsupported by the footnoted source.

I'll call it intellectual laziness ("dishonesty" seems a little strong in the absence of first-hand knowledge of the motivations) - but it certainly doesn't inspire confidence in the meticulousness of the researchers' methods, let alone their analysis.

I'm still in the dark as to whether the researchers accounted for colour vision defects (far more common in men) in their methods.

And gobsmacked as to why they leapt to hand-waving evolutionary psychology explanations, when they found that subjects who spent their girlhood in the UK had a much stronger pink preference than subjects who were raised in China and immigrated to the UK relatively recently.

Frankly, I'd be surprised (and disappointed) if the introduction and discussion sneaked past a reasonably rigorous senior undergraduate class without some probing questions. So what's it doing in Current Biology?

Paul Wilson said...

Cheers for the comment. Interesting about the poor referencing. I seem to see this a lot, especially in papers that get discussed in the media...

Hadn't thought of the issue of colour blindness. Having looked at the supplementary data, which includes a more detailed description of the methodology, the authors state that "208 observers with normal color vision (as verified on the Farnsworth-Munsell 100-hue test) were tested in three different experiments". So it does seem that they controlled for colour blindness.

I do agree with your point about evolutionary psychology. I just don't think they can separate innate and cultural explanations for the differences based on their observations.

Even so, I think the results are at least interesting...

Lauredhel said...

Thanks for spotting that! I managed to read through the supplement, and search it for various terms ("red-green", "color blindness", "defect", "ishihara") and not find that.

I'm curious - what do you find "interesting" about the results? What did it tell you that you didn't already know?

Mich said...

Did anybody think to ask the participants why they chose one colour over another?

I know that my colour preferences are directly linked to an emotional response which in turn is linked to life experience. I'd be interested to hear the participants reasons for choosing specific colours before jumping to any conclusions.

It's the old nature vs nurture argument all over again isn't it?

Paul Wilson said...


"I'm curious - what do you find "interesting" about the results? What did it tell you that you didn't already know?"

I think it told me that women really do like pink more than men do. This was certainly something I would have suspected to be the case (after all, at my primary school the girls washrooms were painted pink and the boys washrooms were painted blue), but did I KNOW it to be the case? Often things that seem to be obviously true, or common sense, turn out to be completely wrong when you look at them closely. That's why we need science in the first place.

Paul Wilson said...

Hi Michelle,

In this particular study, it wouldn't really have been possible to do what you suggest. The participants were asked to choose a colour as quickly as possible (average reaction time for males 1.26 seconds, 1.33 seconds for females). Presumably this is done so the participant doesn't have too much time to think about which colour they ought to like best, and why they like it.

I think a study of the type you suggest would be interesting, but it would be a very different study to this one.

Jolan Sulinski said...

I hate pink BECAUSE I was taught girls were supposed to like it.