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2018
David Myers

Our Perception of Sex

Posted by David Myers Expert Mar 29, 2018

Perceptual illusions are not only great fun, they also remind us of a basic truth: Our perceptions are more than projections of the world into our brain. As our brains assemble sensory inputs they construct our perceptions, based partly on our assumptions. When our brain uses rules that normally give us accurate impressions of the world it can, in some circumstances, fool us. And understanding how we get fooled can teach us how our perceptual system works.

 

A case in point is the famed Müller-Lyer illusion, for which the Italian visual artist Gianni Sarcone gives us two wonderful new examples.

 

Many more informative examples can be found amid the 644 pages of the new Oxford Compendium of Visual Illusions. There I discovered a fascinating phenomenon reported by Gettysburg College psychologist Richard Russell.

 

First (with Professor Russell’s kind permission from his earlier article in Perception) a question:

In the pair of Caucasian faces, below, which looks to be the male, and which the female?

Do you (as did I) perceive the left face as male, the right face as female?

 

Many people do, but in actuality, they are the same androgynous face (created by averaging Caucasian male and female faces), but with one subtle difference: the researchers slightly darkened the skin (but not the lips or the eyes) in the left face and lightened the skin in the right face. Why? Because worldwide and across ethnic groups, Russell and others report, women’s skin around the lips and eyes tends to be lighter than men’s. And that means more contrast between their skin and their lips and eyes.

 

That natural, subtle facial sex difference enabled Russell to recreate what he calls “the illusion of sex” with a second demonstration. This time, he left the skin constant but lightened the lips and eyes of the left face, making it appear male, and he darkened the lips and eyes of the right face, increasing the contrast, making it appear female.

Russell suggests that this helps explain why, in some cultures, women use facial cosmetics. Lipstick and eye shadow amplify the perceived sex difference, he notes, “by exaggerating a sexually dimorphic attribute—facial contrast.”

 

While it had been common for astronauts to spend six months at the ISS, NASA wanted to know what happens when humans spend even longer in space. Depending on the orbit trajectory chosen – which depends on how much fuel you want to take with you – a trip to Mars could take 7 to 9 months (Carter, n.d.). And then once you get there, you probably want to spend some time there. Heck, I spend more than a few days in Australia when I travel there, and that’s just 7,744 miles/12,462 km. And then you have to travel home from Australia – I mean, Mars.

 

If you’re NASA and you have identical twin astronauts, there’s only one reasonable thing to do. You put together a team of researchers who are experts in human physiology, behavioral health, microbiology, and epigenetics to find out everything you can about the twins today. Next, you send one of them into space for twelve months. When the astronaut comes back to earth, repeat the measurements for both astronauts. This is NASA’s Twin Study. Mark Kelly* was the twin who stayed on earth; Scott Kelly was the twin who spent a year aboard the International Space Station (ISS)**.

In January, 2018, NASA shared some preliminary research findings from their twin study.  

 

Another interesting finding concerned what some call the “space gene”, which was alluded to in 2017. Researchers now know that 93% of Scott’s genes returned to normal after landing. However, the remaining 7% point to possible longer term changes in genes related to his immune system, DNA repair, bone formation networks, hypoxia, and hypercapnia.

 

This makes it sound like Scott’s genes underwent some kind of change. Journalists grabbed hold of this and declared that Scott and Mark were no longer twins since their DNA was not the same. This was not what the researchers meant. NASA clarified:

 

Mark and Scott Kelly are still identical twins; Scott’s DNA did not fundamentally change. What researchers did observe are changes in gene expression, which is how your body reacts to your environment. This likely is within the range for humans under stress, such as mountain climbing or SCUBA diving.

 

What changed were not Scott’s genes, but rather his gene expression – in other words, his epigenetic code.

 

A Brief History of Everyone Who Ever Lived by scientist and science writer Adam Rutherford is a nice summary of what we know, what we don’t know, and what we would like to know about genetics and, to a lesser extent, epigenetics.  Our epigenome is what turns genes on and off. Women who have two X chromosomes (that’s most of us) have all the genes on one X chromosome in each of our cells turned off. “In mammals, epigenetic modifications tend to get reset each generation, but some, very limited, rare epigenetic tags appear to be passed down from parent to child, at least for a couple of generations.”  Pregnant women who starved in the Netherlands during the winter of 1944 gave birth to low-birthweight babies (no surprise) who then grew up to give birth to babies who were high-birthweight (surprise). Other research in a rural Swedish community with variable harvests found that boys who experienced a lean year just before entering puberty were more likely to have grandsons – yes, grandsons – who lived longer. But most epigenetic changes are temporary (Rutherford, 2017).

 

In the case of reporting that astronauts Mark and Scott Kelly were no longer identical twins, the journalists were merely reporting what they understood the NASA press release to be saying, so I’m not going to fault them.

 

Earlier this month we read headlines declaring that despite years of research showing that the adult human hippocampus produces stem cells that grow into new neurons, that a new study declares that’s not the case at all. I was poised to pounce on journalists for getting this wrong. But I can’t. Once again, it’s the Public Relations department, this time at the University of California at San Francisco.

 

Now UC San Francisco scientists have shown that in the human hippocampus – a region essential for learning and memory and one of the key places where researchers have been seeking evidence that new neurons continue to be born throughout the lifespan – neurogenesis declines throughout childhood and is undetectable in adults (Weiler, 2018).

 

Rutherford (2017) reminds us that “[j]ournals are not all equal, and publication in a journal is not a mark of truth, merely that the research has passed the standard that warrants entering formal literature and further discussion with other scientists.” This is worth hammering into the heads of our students, our students who are the future writers of press releases, the future writers of news articles, and the future readers of those new articles. Our science journals are just one huge chat room. "Hey! This is what I found!" "Huh. How did find that?" "What if we looked at it this way instead?" "Anna used this other method and found something different. Anyone know why that would produce different results?"

With additional research, we may discover that, indeed, the human hippocampus does not produce new neurons. And we may discover that living in space where a person is subject to the radiation equivalent of 10 chest x-rays a day (Kelly, 2017) does indeed change one’s genes, and not just the epigenetic code. Those who turn to science for definitive answers may find the responses couched in probabilities less than satisfying. But that’s how science works.

 

Here’s a cautionary tale: Everyone knows that tongue-rolling is genetic. If you can roll your tongue, you have the dominant allele for tongue-rolling. As it turns out, everyone is wrong. The research was easy to do. Find a bunch of identical twins and see who could roll their tongues and who couldn’t. If tongue-rolling were completely genetic, each twin pair should be, well, identical in their tongue-rolling ability. Philip Matlock (1952) looked in the mouths of 33 pairs of twins. In 7 pairs, one twin could tongue-roll while the other one could not. And, yes, that date is right; he did this research in 1952. Similar studies in the 1970s found similar results (Martin, 1975; Reedy, Szczes, & Downs, 1971).

If you had asked me last week, “Hey, Sue, is tongue-rolling simply controlled by our genes?” I would have said yes. But now my response is more nuanced. “There’s likely a gene or set of genes that controls it, but there is also probably an epigenetic code that turns that gene or genes on or off for different people. Let me tell you about this interesting research done with identical twins…”

 

The more I learn, the less confidence I have in what I have always known to be true.

 

“Half of what I’m going to tell you is wrong, but I don’t know which half.” I love this quote (or paraphrase?) as it nicely captures the moving nature of science, but I can’t find the origin – and I find that very fitting. My memory says it was something Paul Meehl said to his students, but I can’t find any such reference. A Psychology Today blogger credits an uncited and unnamed surgeon. If you know the origin, please contact me.


References

 

Carter, L. (n.d.). If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there? (Intermediate). Retrieved from http://curious.astro.cornell.edu/physics/64-our-solar-system/planets-and-dwarf-planets/mars/267-if-mars-is-only-about-35-60-million-miles-away-at-close-approach-why-does-it-take-6-8-months-to-get-there-intermediate

 

Kelly, S. (2017). Endurance: A year in space, a lifetime of discovery. New York City: Knopf.

 

Martin, N. G. (1975). No evidence for a genetic basis of tongue rolling or hand clasping. Journal of Heredity, 66(3), 179–180. https://doi.org/doi.org/10.1093/oxfordjournals.jhered.a108608

 

Matlock, P. (1952). Identical twins discordant in tongue-rolling. Journal of Heredity, 43(1), 24. https://doi.org/https://doi.org/10.1093/oxfordjournals.jhered.a106251

 

Reedy, J. J., Szczes, T., & Downs, T. D. (1971). Tongue rolling among twins. Journal of Heredity, 62(2), 125–127. https://doi.org/doi.org/10.1093/oxfordjournals.jhered.a108139

 

Rutherford, A. (2017). A brief history of everyone who has ever lived. New York City: The Experiment.

 

Weiler, N. (2018). Birth of new neurons in the human hippocampus ends in childhood. Retrieved March 24, 2018, from https://www.ucsf.edu/news/2018/03/409986/birth-new-neurons-human-hippocampus-ends-childhood

 

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*Mark Kelly’s wife is Gabrielle Giffords, the US Representative from Arizona who survived an assassination attempt in 2011.  

 

**”at the International Space Station” – I had a hard time deciding on the right preposition to use. Can one be on a space station if one is really floating inside it, except when Velcro-ed to a wall? In seemed to be a better choice, but felt clunky when I read it. I was ready to settle for at. NASA dodges the entire question and uses “aboard the ISS.” If aboard is good enough for NASA, it’s good enough for me. I’m confident we’ll get this figured out before we head to Mars.

Long ago, I read a jest that most people believe in the shaping power of environmental nurture—until they have their second child.

 

That pretty well sums up the results of a not-yet-published survey of 1000 Americans by an Emily Willoughby-led University of Minnesota team. The researchers report that “educated mothers with multiple children” were particularly cognizant of the heritability of traits, adding: “Parents, after all, have the ability to observe firsthand the results of an empirical experiment on the heritability of human traits in their own home. They can see that their children resemble them along multiple dimensions; furthermore, a parent of multiple children can see how the shared environment does not necessarily make them alike.”

 

That has been my wife’s and my experience as parents of three children who share some of our traits, but who were distinct individuals right out of the womb. And perhaps your experience, too, as you compare your children, or observe your own or other siblings?

 

These researchers noted another interesting finding, related to political leanings: When asked about the relative gene and environment contributions to various traits, liberals more than conservatives saw genetics having a strong influence on psychiatric disorders and sexual orientation. As a result, liberals tended not to view sexual orientation as a choice, and they tended to have more compassionate views of those with psychiatric disorders. Conservatives more often saw a strong genetic influence on intelligence and musical ability, thus suggesting that those with these strengths had been largely “born that way” rather than advantaged by opportunity.

A young man, raising funds for his high school football team, knocked on the door of a Chronic Traumatic Encephalopathy (CTE) researcher. And not just any CTE researcher: a CTE researcher who looks specifically at teenage brains. The two sat down, and the young man learned about how concussions are not necessary to trigger CTE; repeated shots to the head will do it. The young man listened, and, in fact, chose CTE as his research project in English. When I read this NPR story, I was hoping for a better ending.

 

And what did the young man decide about playing football? He’s still going to play. “This is something I love. I dedicate myself to [this]. This makes me healthier physically, mentally. I'm doing what I love, making friends, there's a lot of great experiences that I'm having from this.” He did decide, however, to cut back on boxing, so that’s something.

 

When I read this article I was immediately struck by the power of immediate reinforcement over the potential of bad things happening at some unknown time in the distant future. [As an operant conditioning bonus, in the very first paragraph, the student gives us a great example of discriminative stimuli. “He’d look for lights on and listen for kids’ voices.” Those stimuli signaled a greater likelihood of receiving a donation.]

 

But the reinforcement aside, I wondered about the social psychology of playing an intense team sport, like football. The student said, “I’m doing what I love, making friends, there’s a lot of great experiences that I’m having from this.”

 

In Sebastian Junger’s book, War, the author writes about his experience spending 15 months with a U.S. Army platoon in Afghanistan. Once, when out on patrol, the platoon got into a firefight along a road, taking cover behind a rock wall. Afterwards, Junger asked one of the soldiers if he was scared. He said he was. Junger asked why he didn’t run. He said he stayed because the soldier on his left stayed and the soldier on his right stayed.  

 

While still considering the power of groups, my news feed produced a fascinating article on identity fusion. Research “suggest[s] that extreme self-sacrifice is motivated by 'identity fusion', a visceral sense of oneness with the group resulting from intense collective experiences (e.g. painful rituals or the horrors of frontline combat) or from perceptions of shared biology.” Once a person fuses their identity with the group, all it takes is a threat to the group to lead the person to self-sacrifice. And those groups need to be “local” groups, like a team or a platoon. “Extended fusion” to bigger groups like one’s country can happen, but it looks like it can only happen after “local fusion.” Those who have experienced identity fusion with a local group describe the others in the group as family. It’s common to hear teammates and platoon-mates describe each other as brothers (Whitehouse, 2018).

 

What sacrifices are you willing to make for your family?

 

 

References

 

Whitehouse, H. (2018). Dying for the group: Towards a general theory of extreme self-sacrifice. Behavioral and Brain Sciences. https://doi.org/10.1017/S0140525X18000249

In an earlier post, I offered my nominee for psychology’s most misunderstood concept: negative reinforcement (which is not a punishing, but a rewarding event—withdrawing or reducing something aversive, as when taking ibuprofen leads to relief from a headache). 

 

Second place on the most-misunderstood list went to heritability. Students often wrongly think that if intelligence is 50 percent heritable then “half of our intelligence is due to our genes.” Actually, 50 percent heritability would mean that, within the population studied, half of the variation among individuals is attributable to genes.

 

Now my bronze medal award in the most-misunderstood competition: short-term memory. The misuse of the word appeared repeatedly in an otherwise excellent talk I recently heard on care for people with early-stage Alzheimer’s. For example, we were told that “They often have good long-term memory for their earlier life, but have lost their short-term memory for what they did yesterday.”

 

The presenter, in very good company, didn’t understand that psychologists define short-term memory as the seconds-long memory of, for example, the phone number we’re about to enter in our phone, or of an experience we’ve just had and are processing for long-term storage. The dementia-related memory problem described was not the result of short-term memory loss. Rather, it demonstrated an inability to transfer short-term memories into long-term storage, from which the person could retrieve the experience an hour or a day later. (Our memory of yesterday is a long-term memory.)

 

Negative reinforcement, heritability, and short-term memory are my gold, silver, and bronze medal winners among psychology’s popularly misunderstood concepts. Perhaps you have other nominees from your experience?

On most subjective and socially desirable dimensions, we tend to exhibit self-serving bias. We perceive ourselves as more moral than most others, healthier than others, more productive at work, better able to get along with others, and even better drivers. With apologies to Elizabeth Barrett Browning, “How do I love me? Let me count the ways.”

 

But most of us also experience a different sort of social misperception that’s biased in the opposite direction. First, a question: Who goes to more parties—you or others?

 

Across 11 studies, Cornell University’s Sebastian Deri and his colleagues found that university students, mall shoppers, and online respondents perceived others’ social lives to be more active than their own duller life. Other folks, it seems, party more, dine out more, and have more friends and fun.

 

Can you imagine why most people perceive their social lives as comparatively inactive?    

 

Our social perceptions, according to the Deri team, suffer from biased information availability. We compare ourselves not to social reality but to what’s mentally accessible. We hear more about our friends’ activities than we do about the nonevents of their lives. If Alexis goes to a party, we’re more likely to hear about that than if she sits home looking over her toes at the TV.

 

Social media amplifies our sense of social disadvantage. People post selfies while out having fun—which we may browse while sitting home alone. Thus, our normal self-serving perceptions are overcome by a powerful social exposure bias.

 

The others-are-having-more-fun finding joins reports by Jean Twenge and her collaborators that the spread of smart phones and social media have precisely paralleled a recent increase in teen loneliness, depression, and suicide. Twenge reports that

Teens who visit social-networking sites every day but see their friends in person less frequently are the most likely to agree with the statements “A lot of times I feel lonely,” “I often feel left out of things,” and “I often wish I had more good friends.”

 

Does your life seem pallid compared to all the fun others seem to be having?  Do you believe you are not one of the socially active “cool” people? Does your romantic life seem comparatively unexciting? Do you wish you could have as many friends as others seem to?

 

Well, be consoled: most of your friends feel the same way.

 

As Teddy Roosevelt long ago surmised, “Comparison is the thief of joy.”

My colleague, Lindsay Root Luna, has new data showing that virtues correlate. People’s scores intercorrelate on scales assessing humility, justice, wisdom, forgiveness, gratitude, hope, and patience. Show her a forgiving person and she will likely show you a humble, grateful person.

 

Root Luna’s observations triggered my thinking about other human dispositions that come bundled. First, there are the anti-virtues.

 

As the concept of ethnocentricism conveys, prejudices often coexist: anti-gay, anti-immigrant, anti-Black, anti-Muslim, and anti-women sentiments often live inside the same epidermis. People intuitively know this. Thus, as Diana Sanchez and colleagues have observed, White women often feel threatened by someone who displays racism, and men of color by sexism.

 

Likewise, people’s tendencies on the “dark triad”—narcissism, Machiavellianism, and psychopathy—are “substantially intercorrelated.” Show Peter Muris and colleagues a narcissist (perhaps your least favorite politician?), and they’ll show you a likely Machiavellian and amoral person.

 

On the brighter side, some good things, in addition to the virtues, also tend to come wrapped in the same skin. Charles Spearman recognized this long ago with the concept of general intelligence (g). Those who score high in one cognitive domain have some tendency to score higher than average in other areas such as reasoning or spatial ability, or even perceptual speed.

 

Athleticism offers another example of packaged gifts. The ability to run fast is distinct from muscular strength or the eye-hand coordination involved in the precise pitching of a ball. Yet there remains some tendency for athletic excellence in one domain to correlate with that in another. Good tennis players may also be better than average basketball players.

 

Surely this does not exhaust the list. Can you think of other examples of correlated good things and bad things?

In the aftermath of the mass murder at a Florida high school, gun safety advocates reminded us that countries and states with the most guns (which are also the places with the most “good guys with guns”) have the most homicidal and suicidal gun deaths. The United States, for example, has more than 300 million guns and a firearm death rate that is, per person, 46 times that of the largely gun-free UK. Unless we’re to assume that Americans are simply more malevolent, surely this has something to do with gun availability. If so, perhaps, to put this as gently as possible, some new gun safety legislation might be appropriate?

 

President Trump offered an alternative idea—opening more mental hospitals that could house would-be mass murders: “When you have some person like this, you can bring them into a mental institution.”

 

Florida Governor Rick Scott concurred about the implied feasibility of identifying high-risk people: “I want to make it virtually impossible for anyone who has mental issues to use a gun. I want to make it virtually impossible for anyone who is a danger to themselves or others to use a gun.”

 

Although we psychologists might appreciate these extremely high estimations of our discipline’s powers of discernment, the reality is that these aggressors, though harboring anger, have mostly not had distinct psychiatric disorders and their acts are extremely difficult to predict. As one review of 73 studies of nearly 25,000 people concluded, psychology’s “risk assessment tools” have “low to moderate” predictive power. Thus, their “use as sole determinants of detention, sentencing, and release is not supported by the current evidence.”

 

The Florida mass murderer, Nikolas Cruz, is a case in point. Although, in hindsight, it seems obvious that Cruz was a ticking time bomb, a mental health center had deemed him not a threat. True, he was angry and seemingly isolated and depressed, but so are a million or more other teen males—for whom the late psychologist David Lykken in his The Antisocial Personalities offers a tongue-in-cheek solution: “We could avoid two-thirds of all crime simply by putting all able-bodied young men in cryogenic sleep from the age of 12 through 28.”

 

The impossibility of identifying, in advance, high-risk people with mental illness is compounded by the unfairness of a gun ban targeted at “mentally ill” people but not others. Who is mentally ill? A person with a phobia for heights? Someone with obsessive-compulsive disorder? An eating disorder? Obviously, society will need to look beyond psychology for gun violence remedies.