Just good friends? Attraction to opposite-sex friends is common but burdensome

"Every platonic friend I got is some woman I was trying to ****, I made a wrong turn somewhere, and ended up in the friend zone. 'Oh no, I'm in the friend zone!'" Chris Rock.

They were virtually unheard of for most of human history, but today, in many cultures, friendships between men and women are common place. Still, that niggling doubt never seems to go away - is the relationship really entirely platonic?

A new study by April Bleske-Rechek and her colleagues has investigated cross-sex friendships between heterosexual men and women through the prism of evolutionary theory. From a survey of 88 pairs of college students in cross-sex friendships (averaging two years' duration), the researchers found that: men felt more attraction to their female friend than vice versa; that men overestimated how much their friend was attracted to them; and that men's desire to date their female friend was unaffected by whether they (the men) were in a romantic relationship with someone else, whereas females tended to report less desire to date their male friend, if they (the women) were already in a romantic relationship. Male attraction for a female friend was undimmed by the fact their friend had a partner. By contrast women tended to report less attraction for male friends who had partners.

The participants gave their answers after being reassured they'd be kept anonymous, and after agreeing publicly with their friend not to discuss the study afterwards (I bet they stuck to that!).

The pattern of results makes sense from an evolutionary psychology perspective on mating strategies, the researchers said, whereby men have more to gain from short-term sexual encounters, whereas women, who invest more in their offspring (in terms of gestation and child-birth), are more selective.

What about the way people deal with their sexual desires for opposite-sex friends? For a second study, over a hundred heterosexual young men and women (average age 19), and an older sample of 142 men and women (average age 37), answered questions about their cross-sex friendships, including listing the costs and benefits. Among the younger sample, 38 per cent were in a (non-marital) romantic relationship; around 90 per cent of the older sample were married.

Again, the researchers said the findings made sense in terms of evolutionary theory. The older sample, most of whom were immersed in a serious long-term relationship, reported less attraction to their opposite-sex friends than the younger sample did. However, this wasn't case for the older single people - they reported just as much attraction to their opposite-sex friends as the younger participants.

Overall, attraction to an opposite-sex friend was more often seen as a burden rather than a benefit of the friendship. Averaged across both samples, attraction was listed as a cost or complication by 32 per cent of participants - five times more often than it was listed as a benefit or enhancement. For young women, and men and women in the older sample, more attraction to their closest friend was associated with feeling less satisfied with their romantic partner.

Zooming in on gender differences, men more often than women, listed attraction to their female friends as a benefit of the friendship, and they were less likely than women to list it as a cost.

"Our findings offer preliminary support for the proposal that men's and women's experiences in cross-sex friendship reflect their evolved mating strategies," Bleske-Rechek and her team concluded. "Attraction between cross-sex friends is common, and it is perceived more often as a burden than as a benefit." Looking ahead, the researchers said it would be interesting to investigate attraction between homosexual same-sex friends, and whether it's seen by them as a burden or benefit of the friendship.

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Bleske-Rechek A.,, Somers, E., Micke, C., Erickson, L., Matteson, L., Stocco, C., Schumacher, B., and Ritchie, L. (2012). Benefit or burden? Attraction in cross-sex friendship. Journal of Social and Personal Relationships DOI: 10.1177/0265407512443611

Further reading, from the New York Times: "A Man. A Woman. Just Friends?"

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Threaten a man's masculinity and he becomes a short-sighted risk taker

With Britain embroiled in yet another banking scandal, commentators are once again pointing their fingers at the macho culture of the City. "Put a bunch of confident, aggressive men in the same room and reward them for taking risks," Ian Leslie wrote, "and you create a pressure cooker, from which probity and prudence evaporate like steam."

Now a study has cast new light on the role that masculinity may have played in past and present financial crises. Jonathan Weaver and his colleagues at the University of South Florida report that threatening a man's sense of manhood makes him myopic and more prone to take risks, particularly in a public situation. The findings suggest that being surrounded by their sweaty, swaggering alpha-male peers may have provided just the kind of threatening environment to encourage bankers to become short-sighted risk-takers.  

For an initial study, the masculinity of 19 heterosexual male university students was threatened by having them product test a pink bottle of "Sweet Pea" fruit-scented hand lotion; 19 others acted as a comparison group and tested a power drill. Ostensibly as part of a separate study, all the men were then filmed playing a gambling game. They started with $5 and had five chances to bet between $0 and $1 on whether a die roll would turn up odds or evens, with the potential to win or lose the amount they gambled. Over the course of the first four bets, the men who'd had their masculinity challenged tended to bet larger amounts; they also bet the maximum possible amount more often.

A second study was similar but this time the masculinity of half of 73 more men was threatened by having them recall 10 examples of times they'd behaved like a "real man". Chuck Norris aside, because it's difficult for most men to think of 10 examples off the cuff, this challenge has an undermining effect on their sense of masculinity. By contrast, thinking of 2 examples (as the remainder of the participants did) is easy for most men, and has the opposite, manhood enhancing effect. Next, all the men made a series of choices between smaller financial rewards now or larger rewards later. Half of the men in both groups thought they'd have to justify their choices publicly. The take-home finding here was that men who'd had their masculinity challenged, and thought their decisions would be public, tended to make more short-term choices, forfeiting about three times the amount of money available, as compared with men in the other conditions. Presumably acting impetuously in front of a crowd helped the men feel more manly.  

Weaver and his colleagues acknowledged that the way they threatened the manhood of their participants was not a close simulation of the way that masculinity is threatened in a macho banking environment. However, they said that both their interventions had "the psychological consequence of reminding men that manhood is a precarious social status."

"Whether manhood threats were directly implicated in the recent financial crises that continue to plague the US [and UK] economy, the current findings are at least consistent with such an interpretation," they said. "Certainly, they are suggestive enough to warrant further investigation into this critically important question."

A weakness of the studies was the lack of a genuine control group, in which masculinity was neither threatened nor strengthened. As mentioned by the researchers, it would also be useful for further investigations to observe the effect of gender threats on women's risk-taking behaviour.

This new paper builds on several related findings that are pertinent to the role of a macho culture in the recent banking crises; for example: it's been shown that men, but not women, take higher-risk financial bets when surrounded by same-sex peers of similar status; men make more myopic decisions in competitive all-male situations; and male stock traders in London made higher gains on days that their testosterone levels were higher (probably because they took more risks).

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Jonathan R. Weaver, Joseph A. Vandello, & Jennifer K. Bosson (2012). Intrepid, Imprudent, or Impetuous?: The Effects of Gender Threats on Men's Financial Decisions. Psychology of Men &; Masculinity DOI: 10.1037/a0027087

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At what age do babies enter the uncanny valley?

In the 1970s, the roboticist Masahiro Mori noticed a curious phenomenon. As robots became more human-like, their appeal increased but only up to a point. When their human likeness became too realistic (but still not perfect), their appeal plunged. Mori nicknamed this abrupt aversion "the uncanny valley", in reference to the shape of the graph mapping human-likeness and appeal. Are we born with this aversion to the almost-real or does it emerge later?

To find out, David Lewkowicz and Asif Ghazanfar presented nearly a hundred infants (aged between 6 to 12 months) with pairs of faces, to see which they would look at for longer. In the first study, the babies were shown a human face alongside a cartoon face (an "avatar") with enlarged goggle-eyes. The researchers said adults would find the avatar uncanny and would avoid looking at. The key finding here was that six-month-olds spent more time looking at the uncanny avatar, whereas the twelve-month-olds, like adults, spent more time looking at the human face. Based on this dramatic contrast in preference, Lewkowicz and Ghazanfar said the uncanny valley effect emerges gradually between six and twelve months of age.

What was it about the faces that provoked this change in preference in the older babies? In two further studies, the researchers presented the babies with either a goggle-eyed uncanny avatar alongside a more realistic avatar face with normal-sized eyes, or with a human face alongside the realistic avatar. In the first case, all the babies, from 6 to 12 months, spent more time looking at the realistic avatar. In the second case, the babies of all ages spent equal amounts of time looking at the two faces.

These results suggest that none of the babies could distinguish between the realistic avatar and a real human face, and that the older babies in the first study, and all the babies in the second study, must therefore have been using the enlarged eyes to distinguish the goggle-eyed avatar from a human face or realistic avatar face, respectively.

Lewkowicz and Ghazanfar said that the aversion to the goggle-eyed uncanny avatar likely emerged in the older babies as a consequence of their growing expertise with processing human faces, and their association of human faces with positive consequences. However, the older babies' expertise was obviously far from complete because they were unable to tell a realistic avatar from a human face. By 12 months, they can spot uncanny features, it seems, but not a synthetic face. "This limitation, particularly at the end of the first year of life, is interesting," the researchers said, "because infants of this age have already become sufficiently specialised for human faces that they no longer discriminate the faces of other species and of other races [a process known as perceptual narrowing]".

This study builds on recent research showing evidence of the uncanny valley effect in monkeys. From an evolutionary perspective, the researchers said their results were consistent with the idea that the uncanny valley effect emerges as a result of early developmental experience and was "a useful behavioural adaptation because it enables observers to quickly detect anomalies (e.g. disease) and/or aesthetic value (i.e. beauty) of a face."

Critics of this research may feel that it is rather a leap to assume that the uncanny feeling experienced by adults is felt by babies in any way, just because they look at a face more or less. Moreover, the classic uncanny valley effect is about almost-real robots and faces. This study arguably complicates the issue somewhat by introducing specific abnormal features onto synthetic faces, therefore making them look unreal. Whilst it's been shown that abnormal features, such as enlarged eyes, are perceived as uncanny by adults, this could be a different effect from the discomfort caused by not-quite-perfect hyper-realistic entities.

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Lewkowicz, D., and Ghazanfar, A. (2012). The development of the uncanny valley in infants Developmental Psychobiology, 54 (2), 124-132 DOI: 10.1002/dev.20583

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At what age do girls prefer pink?

Crudely speaking, the psychological field of gender development is split between those who see gender differences as learned via socially constructed ideas about gender, and those who believe many gender differences are actually “sex differences”, innate and biologically driven.

In Western cultures, girls consistently prefer pink, boys prefer blue. Which academic camp lays claim to this difference? Past research has made a case, in terms of the evolutionary advantage of finding fruit, for why females might be biologically predisposed to prefer pink and other bright colours. But a new study purports to show that girls only acquire their preference for pink, and boys their aversion to it, at around the age of two to three, just as they’re beginning to talk about and become aware of gender. Vannessa LoBue and Judy DeLoache say their finding undermines the notion of innate sex differences in colour preference. “If females have a biological predisposition to favour colours such as pink, this preference should be evident regardless of experience of the acquisition of gender concepts,” they said.

LoBue and DeLoache presented 192 boys and girls aged between seven months and five years with pairs of small objects (e.g. coasters and plastic clips) and invited them to reach for one. Each item in a pair was identical to the other except for its colour: one was always pink, the other either green, blue, yellow or orange. The key test was whether boys and girls would show a preference for choosing pink objects and at what age such a bias might arise.

At the age of two, but not before, girls chose pink objects more often than boys did, and by age two and a half they demonstrated a clear preference for pink, picking the pink-coloured object more often than you’d expect based on random choice. By the age of four, this was just under 80 per cent of the time – however there was evidence of this bias falling away at age five.

Boys showed the opposite pattern to girls. At the ages of two, four and five, they chose pink less often than you’d expect based on random choices. In fact, their selection of the pink object became progressively more rare, reaching about 20 per cent at age five.

A second experiment zoomed in on the age period of two to three years, to see how colour preferences changed during this crucial year. The same procedure as before was repeated with 64 boys and girls in this age group. Among the children aged under two and a half, both boys and girls chose pink objects around 50 per cent of the time, just as you’d expect if they were choosing randomly and had no real colour preference. Among those aged between two and a half to three years, by contrast, the boys showed a bias against choosing pink and the girls showed a bias in favour of pink.

“This research lends important information to when children develop gender-stereotyped colour preferences …” the researchers said. “Knowing exactly when children begin to demonstrate these tendencies can help lead to fuller understanding of the development of gender-stereotyped behaviour more generally and can be an important marker for future research in this domain.”
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LoBue, V., and DeLoache, J. (2011). Pretty in pink: The early development of gender-stereotyped colour preferences. British Journal of Developmental Psychology, 29 (3), 656-667 DOI: 10.1111/j.2044-835X.2011.02027.x

If you're interested in gender development and the way it's studied and talked about, I recommend Cordelia Fine's book Delusions of Gender.

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Animal-sensitive cells discovered in the human brain

A part of the human brain that's involved in emotion gets particularly excited at the sight of animals, a new study has shown. The brain structure in question is the amygdala: that almond-shaped, sub-cortical bundle of nuclei that used to be considered the brain's fear centre, but which is now known to be involved in many aspects of emotional learning.

Florian Mormann and his colleagues didn't use a brain scanner for their main study. Instead they inserted electrodes directly into the brains of 41 patients with epilepsy, who were undergoing neurosurgery as part of their treatment. This allowed the researchers to present the patients with different pictures and to record the resulting activity of nearly 1,500 individual brain cells, located in the amygdala, hippocampus, and entorhinal cortex (all regions are found in the medial temporal lobe; the latter two are involved in memory).

The dramatic result was that cells in the right-sided amygdala, but not the other regions, were far more likely to respond to pictures of animals, and to be aroused more powerfully by them, as compared with pictures of people (mostly celebrities), landmarks and objects (e.g. food and tools). By contrast, hippocampus cells responded similarly to the different picture categories, whilst the entorhinal cortex cells showed a reduced likelihood of response to pictures of people.

Cells in the right-sided amygdala weren't only more likely to respond to the sight of animals than other pictures, and to do so more powerfully, they also did so extra fast, with a mean latency of 324ms. This wasn't true for the other brain regions. Although this suggests the sight of animals is processed with extra efficiency by the amygdala, the latency is not so short as to suggest bypassing of the cortex (the crumpled, outer layer of the brain associated with conscious processing).

Because the amygdala is involved in fear learning, among other functions, it's tempting to interpret these findings alongside fossil evidence showing that early hominids were preyed on by carnivores, and alongside findings relating to "prepared learning" - this is our innate or early predisposition to have our attention grabbed by threats, such as snakes, faced by our ancestors rather than by contemporary threats like guns. Other research shows that animals are more likely to be detected, than vehicles or even buildings, in change blindness tasks, in which an object or animal appears in a scene that remains otherwise unchanged. However, Mormann's team noted that there was no relation between the likelihood or speed of response of amygdala cells and the nature of the animal pictures as either threatening or harmless.

The researchers said the differential response to animals by amygdala cells is "truly categorical" and "argues in favour of a domain-specific mechanism for processing this biologically important class of stimuli.

"A plausible evolutionary explanation," they continued, "is that the phylogenetic importance of animals, which could represent either predators or prey, has resulted in neural adaptations for the dedicated processing of these biologically salient stimuli."
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F. Mormann, J. Dubois and 10 others (2011). A category-specific response to animals in the right human amygdala. Nature Neuroscience, In Press.

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Men are as motivated by cute baby faces as women

Cuteness as an evolutionary adaptation

Both Charles Darwin and Konrad Lorenz, the pioneering ethologist, wrote about the appeal of baby faces as a possible adaptive mechanism. They surmised that babies' perceived cuteness could be nature's way of ensuring the little terrors get looked after. Now a team led by Morten Kringelbach and Christine Parsons has shown that men are as motivated by baby faces as women. Kringelbach is the same researcher who a few years ago showed that looking at baby faces, as opposed to adult faces, is associated with a distinct pattern of brain activity in the orbitofrontal cortex - a kind of neural "cuteness response".

For the new study, 31 men and 37 women (average age 20 years), all with limited experience of babies, looked at photographs of the faces of 70 babies (aged 3 to 12 months), each shown for five seconds, and rated their attractiveness. These results conformed to cultural stereotypes about gender differences, with the women tending to rate the babies as more attractive than the men (no such gender difference emerged for the rating of adult faces). A desire to conform to gender roles could have played a role here. However, both men and women rated as more attractive those baby faces that most closely conformed to the cute ideal: a large rounded forehead, large low-set eyes, a short and narrow nose and a small chin.

In another part of the experiment, performed either before or after the attractiveness ratings, the participants were able to press a button repeatedly to control how long each baby face remained on the screen. This was taken as a measure of how much the participants were motivated to look at the faces. In this case the men scored just the same as the women. Moreover, for both men and women it was those faces that most closely conformed to the cute ideal that they made the effort to look at for longer.

"Our findings indicate that both men and women appraise what is colloquially described as a 'cute' unfamiliar infant positively, and they will work to see that infant for longer than an infant with less 'cute' features," the researchers said. "This is in line with previous studies showing that 'cuter' infants are rated as more friendly, cheerful, and likeable and are rated as more 'adoptable'."
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Parsons, C., Young, K., Kumari, N., Stein, A., and Kringelbach, M. (2011). The Motivational Salience of Infant Faces Is Similar for Men and Women. PLoS ONE, 6 (5) DOI: 10.1371/journal.pone.0020632

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Is male libido the ultimate cause of war?

"The face that launched a thousand ships ..." Dr Faustus retelling the legend of Helen and the Trojan War that was fought over her.

From the mighty clash of two stags rutting, to the dawn raid of a chimpanzee, much violence in nature is perpetrated by males fighting each other in competition for female mates. A new study claims it's a similar story with humans. Cultural differences, limited resources and technological developments all play a role, but a team of psychologists based in China and Hong Kong believe the ultimate cause of human war rests with the male libido. Historically, they argue that the lure of an attractive female primed the male brain for conflict with other males, an effect that persists in modern man even though its usefulness is largely outdated.

Across four experiments Lei Chang and his team showed that pictures of attractive women or women's legs had a raft of war-relevant effects on heterosexual male participants, including: biasing their judgments to be more bellicose towards hostile countries; speeding their ability to locate an armed soldier on a computer screen; and speeding their ability to recognise and locate war-related words on a computer screen. Equivalent effects after looking at pictures of attractive men were not found for female participants.

The effects on the male participants of looking at attractive women were specific to war. For example, their ability to locate pictures of farmers, as opposed to soldiers, was not enhanced. Moreover, the war-priming effects of attractive women were greater than with other potentially provocative stimuli, such as the national flag. Finally, the men's faster performance after looking at women's legs versus flags was specific to war-related words, as opposed to merely aggressive words.

"The mating-warring association, as shown in these experiments ... presumably unconsciously propels warring behaviour because of the behaviour's past, but not necessarily current, link to reproductive success," the researchers said. They conceded their study had several limitations, not least that war is a collaborative endeavour whilst they had studied individual responses. However, the new results chime with past lab research, showing for example that men, but not women, respond to intergroup threat by increasing their within-group cooperation. And they chime with anthropological research, which has found male warriors in traditional tribal societies have more sexual partners than other men, as do male members of modern street gangs.

"... This is among the first empirical studies to examine the potential mating-warring association," the researchers concluded. "As such this study adds to the diversities of evidence on the effects of mating motives in human males as well as motivating further discussions of the origins of human warfare."
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L Chang, H Lu, H Li, and T Li (2011). The Face That Launched a Thousand Ships: The Mating-Warring Association in Men. Personality and Social Psychology Bulletin DOI: 10.1177/0146167211402216

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A biological mechanism that protects against rape?

When sex researchers compare men and women's genital arousal in response to various stimuli, they generally find that men tend only to be aroused by stimuli that match their declared sexual preferences and subjective feelings, whereas women tend to be aroused by a broad array of sexual material (even involving chimps), irrespective of their declared preferences and subjective feelings. A new study by Kelly Suschinsky and Martin Lalumiere tests the claim, which will surely prove controversial, that this pattern of responding in women is an evolutionary vestige which served in the past to protect women from the genital injury that can come from unwanted sex.

'Substantial ethnographic, historical, and comparative evidence suggests that the threat of unwanted sexual activity has been considerable over human evolutionary history,' the researchers said. Their specific proposal is that women's indiscriminate genital arousal leads to lubrication which reduces the likelihood of injury occurring when unwanted sexual encounters take place.

To test this claim, Suschinsky and Lalumiere presented 15 heterosexual men and 15 heterosexual women (average age in their early twenties), all currently in a sexual relationship, with 14 two-minute audio recordings of various narratives read by a woman from her own perspective. The narratives varied in whether or not a sexual encounter occurred between a man and a woman, whether or not violence took place, and whether or not the activities were consensual.

Consistent with past research, the men's genital arousal was far more specific, tending to occur most strongly in response to a consensual, non-violent sexual encounter, which was also the scenario they said they found most arousing. By contrast, the women's genital arousal was far more uniform across all the sexual scenarios. There was one anomaly - their genital arousal to non-consensual, but otherwise nonviolent, sex was lower than for consensual, non-violent sex, but was still significantly higher than their response to neutral scenarios. Like the men, the women's subjective feeling of arousal was far more targeted, being much higher for the consensual, non-violent scenario than the others. Both sexes reported finding the violent or non-consensual scenarios unpleasant and anxiety provoking.

Suschinsky and Lalumiere said their results support what they call the 'preparation hypothesis', adding to past research showing, for example, that some women report experiencing genital lubrication during rape. The researchers acknowledged some limitations in their study. In particular, the scenarios were all told from a woman's perspective. However, they said that past research had shown men tend to find this narrative perspective particularly arousing, so this methodological imbalance is unlikely to explain the results. The researchers also acknowledged that their sample were young and sexually active, and likely to be fairly sexually liberal given that they'd volunteered for a study of this kind. 'We recommend that this study be replicated with a larger and more diverse sample,' they said.

Given the sensitivity of this research topic, and in particular the possibility that its message might be exploited to justify immoral acts, it's worth heeding the words of Mary Roach in her book Bonk:

'It is important to remember,' she writes, that 'it is the mind that speaks to a woman’s heart, not the vaginal walls... Rape offers a plangent illustration of this fact. I learned in a paper by Roy Levin that rape victims occasionally report having responded physically, even though their emotional state was a mixture of fear, anger and revulsion. ... Regardless of the mechanisms that may or may not explain a rape victim’s physical state, a rapist’s defense based upon evidence of arousal has, to quote Levin, "no intrinsic validity and should be disregarded".'

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Suschinsky, K., and Lalumiere, M. (2010). Prepared for Anything?: An Investigation of Female Genital Arousal in Response to Rape Cues. Psychological Science DOI: 10.1177/0956797610394660

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