It’s been too long since I have made regular postings to the Beauty Blog. I am happy to report that I am back and ready to go! Just to get started, I have decided that every so often I will be revisiting the topics of earlier postings, emphasizing how subsequent research supports – and does not support – the original posting. My first posting for this blog, Is Beauty More Rewarding for Men?, focused on a study that found that the medial orbital frontal cortex was more active in men than in women when viewing beautiful faces (Cloutier, et.al., 2008). Subsequent research suggests the following:
- one study found increased mofc activity while viewing attractive faces when compared to non-attractive faces, but sex differences in mofc activity were not reported (Tsukiura & Cabeza, 2010)
- several studies continue to find mofc activity when appetitive items are presented (e.g., Plassmann, et.al. 2010)
The possibility that increased mofc activity is a characteristic of the human male response to beautiful faces is less likely now than in 2008. There does continue to be research that supports some notion of an appetitive function to mofc activity (though, see Smith & Huettel, 2010 for a review of methodological issues related to this type of research).
Image courtesy of Wikipedia Commons.
Cloutier, J., Heatherton, T., Whalen, P., & Kelley, W. (2008). Are Attractive People Rewarding? Sex Differences in the Neural Substrates of Facial Attractiveness Journal of Cognitive Neuroscience, 20 (6), 941-951 DOI: 10.1162/jocn.2008.20062
Plassmann H, O’Doherty JP, & Rangel A (2010). Appetitive and aversive goal values are encoded in the medial orbitofrontal cortex at the time of decision making. The Journal of neuroscience : the official journal of the Society for Neuroscience, 30 (32), 10799-808 PMID: 20702709
Smith, D., & Huettel, S. (2010). Decision neuroscience: neuroeconomics Wiley Interdisciplinary Reviews: Cognitive Science, 1 (6), 854-871 DOI: 10.1002/wcs.73
Tsukiura T, & Cabeza R (2010). Shared brain activity for aesthetic and moral judgments: implications for the Beauty-is-Good stereotype. Social cognitive and affective neuroscience PMID: 20231177
Platek & Singh (2010) report that stimuli depicting optimal waist-hip ratios (~0.70) activate the “reward center” in men’s brains; while stimuli depicting body mass index do not. They conclude that BMI preferences are therefore more culturally determined and, by suggestion, that WHR preferences are the result of evolved psychological mechanisms. I will point-out at the outset: this conclusion is not supported by their data.
An example of the stimuli used in this research appears to the right (from Singh & Randall, 2007). The stimuli consist of partial body photographs of women who have had fat surgically removed from their abdomens and surgically implanted into their buttocks. The result is that each woman more-or-less maintains the same BMI while exhibiting a more attractive WHR. (For a criticism of over-interpreting the significance of the current studies using micrograft surgery, click here). In this study, fMRIs were taken while men viewed these images. Platek & Singh found that “reward centers” in the brain were activated by stimuli depicting more optimal WHRs; while stimuli depicting variation in BMI did not.
- No stimuli depicted an optimally attractive BMI (range – apparently – was from 21.13-26.36; optimally attractive BMI is ~18-19)
- Stimuli consisted of only a limited area of each woman’s body
- Activation of the “reward center” only indicates that the viewer finds the stimulus rewarding
- Activation of the “reward center” does not imply innate preferences or the activation of an evolved psychological mechanism
- Caution should be maintained in interpreting fMRI data involving “reward centers” in the brain as a recent study of test-retest reliabilities in these measurements revealed correlation coefficients (ICCs) ranging from -0.15-0.44) (Fliessbach et.al., 2010)
- Remember that arguments – even weak ones – which utilize topographical depictions of brain activity can be unusually persuasive (McCabe, 2007)
- This study provides some objective confirmation that men’s attractiveness ratings correspond to the activation of “reward centers” in the brain
The methodology used here does not provide a convincing head-to-head comparison of the relative importance of BMI or WHR in attractiveness ratings. It also does not provide evidence of an innate preference for WHR nor of a cultural influence on BMI preference.
Fliessbach, K., Rohe, T., Linder, N., Trautner, P., Elger, C., & Weber, B. (2010). Retest reliability of reward-related BOLD signals NeuroImage, 50 (3), 1168-1176 DOI: 10.1016/j.neuroimage.2010.01.036
MCCABE, D., & CASTEL, A. (2008). Seeing is believing: The effect of brain images on judgments of scientific reasoning☆☆☆ Cognition, 107 (1), 343-352 DOI: 10.1016/j.cognition.2007.07.017
Steven M. Platek, & Devendra Singh (2010). Optimal Waist-to-Hip Ratios in Women Activate Neural Reward Centers in Men PLoS ONE : 10.1371/journal.pone.0009042
Singh, D., & Randall, P. (2007). Beauty is in the eye of the plastic surgeon: Waist–hip ratio (WHR) and women’s attractiveness Personality and Individual Differences, 43 (2), 329-340 DOI: 10.1016/j.paid.2006.12.003
The bulk of contemporary research supports the conclusion that men value beauty in potential long-term partners more than women do. One potential explanation for this sex difference is that men find beauty more rewarding than do women. Several studies have explored the activity in the brain’s reward circuitry when people view beautiful faces. Jasmin Cloutier and colleagues  are the first to report finding evidence of sex differences in this circuitry in response to attractive faces (Fig 1). They found that men showed more activity in the medial orbital frontal cortex (mOFC) than did women.
Figure 1. Error bars show standard error of the mean. The interaction of attractiveness and sex was significant: F(1, 46) = 4.54, p < .05].
Multiple studies have clearly connected the mOFC with reward and this study shows a significant sex difference in mOFC response to attractive faces. The tendency for many will be to interpret the study as showing that men find beauty more intrinsically rewarding than women. The authors caution against drawing this conclusion too quickly. As they point out, it is premature to conclude that men find beauty more rewarding. We do not yet know precisely what role the mOFC plays in the reward circuitry. For example, Kim et.al. (2007) found evidence that the mOFC may be involved in a slower and more accurate deliberative decision-making system that is appended to the more automatic processing done in the nucleus accumbens (NAC) – a part of the reward system that did not show sex differences in Cloutier’s study.
It may be that while men and women were given the same instructions in this study: ‘Using a 1-4 scale, rate faces on how attractive they are.’ they may actually have been performing different activities. Women may have been responding automatically or aesthetically. Men, in addition, may have been attempting to evaluate who to approach, or who might be more receptive, etc. Until we have a clearer understanding of the mOFC’s role in this sort of task, we cannot be sure about how to understand this difference.
There is one methodological issue that I have not been able to evaluate from the article. The facial stimuli used in this study displayed either a neutral expression or a slight smile and the researchers do report equating the faces. As a technical point, I am curious about the exact nature of the equating. Since faces with slight smiles have been shown to elicit increased activity in the mOFC (O’Doherty et.al., 2003) it is important to know that the ratio of neutral to smiling expressions was identical in the photographs of the men and women used as stimuli.
This is a study worth reading – and one to track in RSS feeds and citation indexes!
Cloutier, J, Heatherton, T.F., Whalen, P.J., & Kelley, W.M. (2008). Are Attractive People Rewarding? Sex Differences in the Neural Substrates of Facial Attractiveness. Journal of Cognitive Neuroscience 20:6, pp. 941–951.
Kim, H., Adolphs, R., John P. O’Doherty, J.P., & Shimojo, S. (2007). Temporal isolation of neural processes underlying face preference decisions. Proceedings of the National Academy of Sciences 104:46, pp. 18253–18258.
O’Doherty, J., Winston, J., Critchley, H., Perrett, D., Burt, D.M. & Dolan, R.J. (2003). Beauty in a smile: the role of medial orbitofrontal cortex in facial attractiveness. Neuropsychologia 41(2):147-55.