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Archive for the ‘Sex/Gender Differences’ Category

Looking Younger…. Looking Less Masculine?

December 29, 2009 10 comments

Egan & Cordan (2008) digitally altered the faces of 17-year-old girls (n=10) to look either younger (morphed to appear similar to the prototype of 10-year-old girls – top row) or older (similar to the prototype of 20-year-old women – bottom row). Additionally, some stimuli were altered by adding digital make-up (right column). The authors had forensic interests and were exploring the effect of alcohol consumption on judgments of age and attractiveness. As a result, they did not report the specific data on attractiveness ratings alone, but, did conclude that faces that appear younger are found more attractive. Raters consisted of an equal number of adult women and men between the ages of 18-70.

The faces were manipulated using proprietary software, Psychomorph. To my eye, the morphed images look good, though, there appear to be distortions in the ears of the “older” faces. Eye size, distance between eyes, lips, forehead height, hair, and clothes do not appear different (to my eye) between the “younger” and the “older” sample stimuli. Though there may be a sense of greater protrusion in the “older” forehead…. The primary apparent differences are a larger nose and longer lower face in the “older” version.

While we don’t have the specific data reported in this paper, the conclusions are consistent with what is generally asserted: looking young is attractive in human females. At least one contributing reason for this attraction to youthful appearance in female faces is the increased rate of development in male faces at puberty, relative to female faces. That is, men’s and women’s faces show the same growth spurt: but males show this growth more markedly. This variation results in larger noses, mandibles, and sinuses (along with brows and cheekbones) in men.

Since these areas are larger in men, larger features become masculine features. Since these facial features are smaller in women, smaller ones become feminine. Another way to conceptualize this: looking younger looks less masculine.  To my way of thinking, this explains what might appear to be a disturbing preference in both men and women for female faces with some prepubescent structural characteristics.

Wayne Hooke

ResearchBlogging.orgEgan, V., & Cordan, G. (2009). Barely legal: Is attraction and estimated age of young female faces disrupted by alcohol use, make up, and the sex of the observer? British Journal of Psychology, 100 (2), 415-427 DOI: 10.1348/000712608X357858

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Does Size Matter?

November 16, 2009 2 comments

According to Rebecca Sear and Frank Marlowe (2009), not to Hadza women. For the record, as used here, the word “size” means “height”. If you were thinking something more explicitly sexual (like penis size), it might matter. 40% of Hadza women report valuing looks in a mate (which in the just-linked survey includes a category labelled “good genitals”). But in regard to our specific question, Sear & Marlowe found that the proportion of female-taller marriages among the Hadza did not differ from chance expectations and that any reference to a man’s body size was mostly absent in Hadza women’s elaborations of what they looked for in a husband. Given that Hadza women tend to have more say in marriage decisions, this suggests that height is not viewed as particularly important to women in this society. This article has been attracting some attention – and the discussion has been mostly worthwhile and constructive. I think two things should be emphasized. The first is that this sort of data does not challenge a thoughtful and scientific approach to evolutionary psychology. Genes can influence behavior without reaching the comprehensive level of instinct. Counterexamples can inform, but do not end the discussion. The second is that this sort of data does present challenges both to some rather strong specific assertions about human male height in recent research (Nettle, 2005), (Pawlowski, et.al., 2000), (Mueller & Mazur, 2002) and to the sometimes found tendency to over interpret the evolutionary causes of specific data sets.

Strengths

  • This study is part of a very thoughtful approach to studying evolutionary anthropology.
  • The Hadza continue to live a hunter-gatherer lifestyle.

Cautions

  • It is possible that the Hadza are atypical in their approach to male height – since they are closely related to pygmy populations:with males averaging about 160 cm in height (5’3″), with less variation in height than in most other populations.

Wayne Hooke

Image courtesy of Idobi/Wikipedia Commons (2007)

 

ResearchBlogging.orgSear, R., & Marlowe, F. (2009). How universal are human mate choices? Size does not matter when Hadza foragers are choosing a mate Biology Letters, 5 (5), 606-609 DOI: 10.1098/rsbl.2009.0342

Androgyny Capitulates to Cosmetology

October 25, 2009 2 comments

Richard Russell of Harvard University has won third prize in the 2009 Best Visual Illusion of the Year Contest with his illusion of sex submission. The faces to the right both were created by averaging male and female faces to create an androgynous substrate that was then modified to exhibit the typical contrast differences found between female and male faces (below right). While the face is the same in both images, people typically see the face on the left as a woman’s and the face on the right as a man’s. This is because the underlying identical, androgynous face has been tonally modified to exhibit typical sex differences.

The image to the right shows these typical tonal differences. The leftmost image to the right (the predominantly white one) shows that areas around the eyes and lips are typically darker in women than men, and that skin tone is typically lighter. The rightmost image shows that the typical male- relative to the typical female – has lighter areas in the eyes/lips and darker skin.

Russell asserts two interesting things:

  • these characteristic tonal differences influence our perception of sex, and
  • the typical, recommended use of cosmetics by women enhances female characteristics.

I have not been able to access the full-text of Russell’s (2009) preprint article and it appears that the link to it at his web page has been severed. The references/links below provide some additional detail.

Wayne Hooke

ResearchBlogging.orgRussell, R. (in press). A sex difference in facial pigmentation and its exaggerationby cosmetics. Perception.

Why Cosmetics Work: More Depth To Facial Differences Between Men And Women Than Presumed. (n.d.). . Retrieved October 25, 2009, from http://www.sciencedaily.com/releases/2009/10/091020153100.htm.

Richard Russell – Research. (n.d.). . Retrieved October 25, 2009, from http://public.gettysburg.edu/~rrussell/research.html.

Tonal graphic from:

Frost, P. (2009, October 1). Facial color and sex recognition. Evo and Proud. Retrieved October 25, 2009, fromhttp://evoandproud.blogspot.com/2009/10/facial-skin-color-and-sex-recognition.html.

Say “Cheese!”

September 2, 2009 2 comments

Using data from the Wisconsin Longitudinal Study, Markus Jokela (2009) has found an association between the rated attractiveness of yearbook photos and reproductive success in a contemporary industrial/technological population. This study is significant because it offers real data suggesting that attractiveness in humans can pay-off in tangible evolutionary terms in the modern world. The estimated pay-off, in this case, was at about half the rate of the average selection gradient reported in a review of non-human natural selection. Assuming no change in correlation rates and no correlations with other reproductively relevant traits (both are questionable assumptions), modern humans living in industrial/technological societies should be getting more beautiful at the rate of about 0.02 standard deviations per generation. For comparison, Dr. Jakela points out in his blog that an equivalent change in height would be about 0.08 inches (about .20 cm) per generation.

Implications

  • The least attractive quartile of men (bottom 25%) had 13% fewer children (at age 53-56) than did all other men, though the lowest p level was .07. This suggests that for modern men, not being unattractive may be more important than being attractive.
  • Attractive women (third quartile or those in the 50th-75th percentiles) had 16% more children on average than did the least attractive 50% of women while the most attractive women (75th to 99th percentiles) had 6% more children than did the least attractive 50%. These relationships were statistically significant. This suggests that the most attractive (beautiful) women may use different reproductive strategies than attractive women or that beautiful women have a preference for smaller family size or….

Strengths

  • Large sample
  • Long-term, longitudinal data

Cautions

  • WLS data include mostly white subjects (from one US state only)
  • Attractiveness ratings of yearbook photos taken in 1957 were made by students in 2004
  • No inter-rater reliability data reported
  • Attractiveness ratings were primarily of headshots like those above
  • Attractiveness was rated at only one point in the life-span
  • There are no non-high-school graduate subjects

Wayne Hooke

Photo courtesy of Jay Hernandez: Wikipedia Commons

ResearchBlogging.orgJokela, M. (2009). Physical attractiveness and reproductive success in humans: evidence from the late 20th century United States☆ Evolution and Human Behavior, 30 (5), 342-350 DOI: 10.1016/j.evolhumbehav.2009.03.006

Size UK

August 13, 2009 Leave a comment

Wells, et. al. (2007), have published data from 3D body scans taken from a 9617 member, cross-sectional sample of UK adults (stratified by age and SES). The study seems intended to gather commercial (garment sizing information) and health related information, but does have some implications for beauty research.

Implications:

  • Body shape correlates with age in females more obviously than in males.
  • Females more likely to become “apples” – or proportionally more similar to males – with age.
  • BMI is not a good predictor of body shape/proportion or waist circumference: at least at the border of the overweight range. Male subjects with a BMI between 24-25 had waist circumferences ranging from 29.7″ to 43.3″ while female subjects ranged from 28.6″ to 44.8″ (a 3.5 standard deviation range in waist circumference for a narrow range of BMI).
  • BMI is insensitive to age associated body weight redistributions.
  • Height and circumference explains most of the variance in weight in both men (91.7%) and women (94.8%). Thus, visual cues are strong predictors of weight.    

Beauty relevant findings:

  • Rank order of strongest predictors of weight in women: height, hip, bust, thigh, and waist.
  • Rank order of strongest predictors of weight in men: height, waist, chest, and thigh.
  • Thigh, arm, and waist girths are strongly(?) related to body fat – implied but not directly addressed in this article.
  • After age 30, mean male waist-hip-chest measurements maintain relatively constant ratios (see Fig. 2A).
  • After age 30, mean female waist circumference increases relative to hip, chest, and bust: leading to a decreased tendency toward hourglass figures with age (see Fig. 2B).

  • Average male waist circumference increases about 0.2″ per decade.
  • Average female waist circumference increases about 1.1″ per decade.

Strengths

  • Total body measurements from 3D scans accurate to 0.2″ were used
  • Large sample
  • Point-cloud data may be accessible to future research on attractiveness

Limitations

  • Sample may not be representative
  • Cross-sectional data do not identify individual developmental trajectories: some of the relationships in the data could be cohort specific

 

Wayne Hooke

ResearchBlogging.orgWells JC, Treleaven P, & Cole TJ (2007). BMI compared with 3-dimensional body shape: the UK National Sizing Survey. The American journal of clinical nutrition, 85 (2), 419-25 PMID: 17284738

Another Eye Tracking Study of Female Body Attractiveness

July 30, 2009 3 comments

Seda Dural et.al. (2008) used eye tracking combined with attractiveness ratings to explore the effect of altering waist-hip ratio and body fat levels in figures generated from 3D modeling software.

The stimuli were presented individually to 50 males and 50 females aged 18-22 (probably Turkish college students) on an LCD screen for viewing and rated for attractiveness while eye movements were tracked using, what seems to be, in-lab created eye tracking hardware. (The article is published in Turkish and I have been forced to rely on the English language summary combined with obscure, computer-generated translations of sections of the full text.) That being said, the stimuli are very similar to those used in Singh’s original studies, though more detail and dimensionality are visible. Attractiveness ratings data are contained in this chart:

For eye tracking analysis, the authors divided the figures into 3 areas:

and used eye tracking data from the most and least attractive stimuli and found that raters looked more often at area B than at areas A and C in both the most and least attractive stimulus figures. The authors conclude that their study provides significant support for the role of waist-hip ratio in the evaluation of female body attractiveness.

Strengths:

  • Utilized 3D software to generate stimulus figures
  • Utilized eye tracking data
  • Non-U.S. college student sample

Cautions:

  • Considering that there is: minimal variation in section A across the 3 weight categories; minimal variation in section C within weight categories; and the most variation between all stimuli in section B; it is possible that the subjects in this study learned that section B contained the most variable information in the stimuli and that section B viewing frequencies are an artifact of the experimental controls themselves
  • As the table above shows (labeled Sekel 5), normal body weight images were significantly more attractive than either under or over weight images
  • Eye fixations in section B do not necessarily indicate that attention is being directed to waist-hip ratio (Cornelissen, 2009)

All-in-all, this study further confirms that both total body fat and body fat distribution as revealed in the WHR are components of female body attractiveness. The eye tracking data, however, do not support the assertion that WHR is the primary determinant of body attractiveness in women.

Wayne Hooke

ResearchBlogging.orgDural, Seda, Cetinkaya, Hakan, Gulbetekin, Evrim (2008). The role of waist-to-hip ratio in evaluation of female physical attractiveness: Eye-tracker data.
Kadinin fiziksel cekiciliinin deerlendirilmesinde bel-kalca-oraninin rolu: Goz-izleme sistemi verileri. Turk Psikoloji Dergisi, 23(61), 75-88

No Evidence of the Good Genes Hypothesis Found

February 20, 2009 13 comments

Using photographs of real men, Peters, et.al (2009) found no evidence of a preference for either masculinized or symmetric male faces or bodies in ovulating women.

Previous studies that have found a relationship between ovulation and attraction to masculine features have used computer-morphed images that are weak in ecological validity. This study used photographs of actual men, like the ones below.

Masculinity, attractiveness, and symmetry ratings of the stimuli appear to approximate a normal distribution, strengthening the ecological validity of this study. The only noteworthy limitation in this design is that there were no objective measurements of masculinity or symmetry – only subjective ratings were used.

The authors were also careful to use precise measurements of ovulation to ensure that the ratings of women in the ovulatory phase were well-within the previously identified six-day long sexually active phase of the menstrual cycle.

Wayne Hooke

Marianne Peters, Leigh W. Simmons, Gillian Rhodes (2009). Preferences across the Menstrual Cycle for Masculinity and Symmetry in Photographs of Male Faces and Bodies PLoS ONE, 4 (1) DOI: 10.1371/journal.pone.0004138
ResearchBlogging.org