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Starting college can be awkward enough, but imagine showing up at freshman orientation and having to pose for a nude photo. Well, from the 1880s to the 1970s, that's exactly what happened at Ivy League and Seven.

Sisters schools like Yale, Harvard, and Wellesley. They were called posture photos. Schools took them to evaluate new students' posture because they thought bad posture could lead to health problems.

Since they were supposed to be for medical reasons and were taken at same-sex schools, it wasn't considered that weird— at least, not in the beginning. Things got creepier in 1940, when the schools gave a psychologist named William Sheldon access to the photos, which he used to investigate if there's a link between body shape and personality. Sheldon used the photos in his research for decades without the students' consent.

His work was shut down in the 1960s, and today we know it had a ton of problems— and that your body shape does not actually determine your personality. Before the studies started at colleges, Sheldon was one of the most popular psychologists of the day. In the 1940s, he published three books about his research, where he proposed there are three genetically-determined body types, or somatotypes.

There were endomorphs, who were pear-shaped with a lot of body fat, especially around the stomach, which Sheldon named after the part of the embryo that develops into internal organs. Then there were mesomorphs, who were muscular and lean, after the part of the embryo that becomes bones and muscle. And finally, ectomorphs were long and skinny, after the part that becomes the skin and nervous system.

Sheldon said most people were a mix of each somatotype, and he would score people on a scale of one to seven for each type based on their measurements—so a 7-1-1 would be a pure endomorph, while a 4-4-4 would be average. Sheldon also suggested there are three kinds of temperament, or personality, that were each linked to the different somatotypes. He thought endomorphs were relaxed and affectionate—what he called viscerotonic.

Meanwhile, mesomorphs were active, aggressive, and dominant—also known as somotonic. Finally, ectomorphs were introverted, sensitive, and self-conscious, which he labeled cerebrotonic. The link between body type and personality became known as constitutional psychology, and it became a huge trend, like how people are sometimes obsessed with their horoscopes.

Magazines gave readers all kinds of ways to understand what their body supposedly said about them. Sheldon had gathered some convincing evidence by photographing and observing the behavior of university students, so other psychologists bought into the idea, which ultimately led the Ivy League and Seven Sisters schools to give Sheldon access to the posture photos. Since he wasn't using biographies of the students, the photos were mainly to improve.

Sheldon's evidence that somatotypes exist. For over twenty years, he collected tens of thousands of photos, and in 1954, he published a book called The Atlas of Men, which contained hundreds of male, nude photos as examples of every somatotype. Sheldon also tried to make an Atlas of Women, but that's when things started to fall apart.

In 1950, some of his female photos were displayed by the University of Washington, where one young woman saw them and told her parents, who then mobilized a small army of lawyers to destroy many of Sheldon's female photos. Around then, Sheldon's former assistant, Barbara Honeyman Heath, came out with a ton of criticism about Sheldon's work, including that he tampered with evidence for The Atlas of Men. After World War II, people were especially nervous about linking physical features to personality and performance, since that was a little too similar to the whole “Aryan master race” thing.

Because of that, schools finally became wary of Sheldon. Between that and doctors realizing that posture wasn't as related to health as they thought, schools decided to phase out posture photos during the ‘60s and ‘70s. Today, constitutional psychology has pretty much been debunked, and besides the consent issue, we've found plenty of other problems with Sheldon's research.

For one thing, it was a little too subjective: Sheldon did a lot of the ratings himself, and since he knew what connections he was looking for, he probably skewed the results in his favor. For example, he observed 200 young boys with a history of criminal activity, and then wrote short biographies and took pictures of each of them. He noticed most of the boys with aggressive personalities were mesomorphs, so he used that to support his hypothesis that mesomorphs are aggressive.

But it's much more likely that many violent crimes happen to be committed by muscular guys, not that muscles automatically equal aggression. Constitutional psychology just reinforced stereotypes, like the dominant jock or the nervous, skinny kid. His research also didn't account for how body shape can change with age.

On top of that, researchers think the ultimate goal of Sheldon's research was to breed a superior race of humans by pairing people up based on somatotypes. Which is kiiind of a huge red flag. These days, we still use the concept of somatotypes for fitness reasons, but researchers have created a formula to figure them out instead of just looking at photos, and we know they don't say anything about personality.

To evaluate someone's temperament, we use mind-based tests like the Big 5, which measures traits like extraversion, agreeableness, and neuroticism. We also know personality can change over time—someone might become more agreeable as they get older, for example. And there's definitely no fast-and-easy way to determine someone's personality based on their body shape.

No matter how many naked pictures of college students you look at. Thanks for watching this episode of SciShow Psych! If you'd like to learn more about how psychologists study personality these days, check out our video about whether personality tests actually mean anything. [♪ OUTRO].