Each week, we read what's going on the world of science and bring the wildest findings straight to you. Here's the latest:

People make assumptions about you based on your body type

In 2007, Princeton psychologist Alexander Todorov published a paper that found that the way people judged others’ faces—their quick first impressions—could predict the winners of about 70 percent of the races for US senator and state governor in the 2006 elections. We use faces to make rapid inferences about their personalities, he argued, and then make decisions accordingly.

But out in the world, we don’t just interact with floating heads—they’re usually connected to bodies, too. In a new paper in Psychological Science, researchers examined which personality traits are associated with different body types.

“It has been known for some time that height and weight contribute to social and personality judgments,” Ying Hu, a psychological scientist at the University of Texas at Dallas, tells me. “However, there is much more to body shape than height and weight. Many features such as curviness, waist height, etc., are easily perceived and might also figure into the inferences we make about a person’s traits.”

She and her collaborators created 140 realistic body models, 70 female and 70 male. They found that active traits, like “quarrelsome” or “enthusiastic” were associated with more “shaped” bodies, while passive traits, like “trustworthy” or “easy-going”, were associated with rectangular bodies— bodies where curves were evenly proportioned and waists were undefined.

“Active traits included both positive traits, such as extroverted and self-confident, and negative traits, such as irritable and quarrelsome,” she says. “Thus, a pear-shaped women and a chiseled man were both seen as having a more active set of personality traits that a person with less defined body shape. This general principle applied both to male and female bodies.” They also found that heavier people were rated with less positive traits, like carelessness or incompetence, compared to slimmer people.

Of course, our judgments are rooted in the specific historical and cultural context we live in now. In previous eras, when food was scarce, people with larger figures were interpreted completely differently. So our associations and perceptions are capable of change. Recognizing what they are now is important though, and not just for the sake of our elections.

“We hope that these findings help us be aware that we spontaneously stereotype people based on their body shapes—and to try to avoid making these unfounded judgments,” Hu tells me.

Your expectations about whether something is going to hurt have a lot to do with how much pain you actually feel

What we feel is largely influenced by what we expect to feel. And so is the way we learn: If a new experience confirms a prior belief or expectation, people learn more from it than an experience that challenges our beliefs.

“This is called a 'confirmation bias': learning selectively from information that's consistent with your original beliefs, and discounting/ignoring information that's inconsistent with the original belief,” Marieke Jepma, a cognitive psychologist at University of Amsterdam, explains.

This can make us feel better when it comes to phenomena like the placebo effect, but is not so enjoyable when it comes to pain. In a new study in Nature Human Behavior, Jepma and other researchers looked at how expectations influenced the perception of pain, both through subjective reports and brain imaging.

In the study, participants were taught to associate visual cues with low or high-temperature heat, so that when they saw a cue they expected either low or high pain. Then the visual cues were shown again, but the cues were no longer related to heat intensity. The researchers asked the subjects to report how much pain they expected after each cue, and how much pain they actually experienced.

They found that people said they felt more pain when they expected to. When the researchers looked at the brain activity, they found that the same levels of heat evoked stronger activity in the brain's “pain network” when people expected high pain than when they expected low pain.

“Our finding that expectations influenced a network of brain regions involved in pain processing suggests that expectations can have a rather 'deep' effect, and really influence the pain-generating process in the brain,” Jepma tells me. “Previous studies have shown that expectations about pain can even influence pain-evoked activity in the spinal cord, so at a very early stage. This suggests people were not ‘just making it up.’”

Their findings could have implications for people with chronic pain, or people who are at risk for developing chronic pain, Jepma says, though their current study was done in pain-free people, so further testing needs to be done in chronic pain patients.

“When someone holds very negative beliefs about pain, the effects we found may interfere with recovery,” she says. “On the other hand, however, the reverse could also be true: positive expectations could reduce perceived pain and promote recovery, thereby making people more resilient against pain chronification.”

Finally, a study showing that women who get abortions are not more likely to develop depression

As abortion continues to be debated politically, researchers have struggled to design studies that look at abortion’s effects on health and well-being. Most of the studies done don’t have appropriate comparison groups, or are done retrospectively. The Turnaway Study out of the Advancing New Standards in Reproductive Health (ANSIRH), a research group at the University of California, San Francisco (UCSF), is the first study in the US to look at the impact of receiving versus being denied a wanted abortion for women and their children.

Diana Greene Foster, a professor at UCSF in obstetrics, gynecology and reproductive sciences, and her colleagues followed almost 1,000 women who sought abortions at 30 facilities across the country over five years.

Some were turned away because they were over the gestational limit—meaning they were too far along—and carried the pregnancy to term. These women were compared to those who were under the limit, and were able to get abortions. “Women above and below the limit were very similar but for a few weeks of pregnancy,” Foster tells me.

They found that the women who did get abortions were not more likely than those who didn’t to have depression, anxiety, or suicidal ideation. Five years later, 95 percent of women reported that the abortion was the right decision.

“Women give many reasons for wanting to end an unwanted pregnancy – not having enough money to raise a baby, wanting to be able to take care of the children they already have, wanting to have a child later under better circumstances, wanting to achieve other life plans,” Foster says. “And we find they are making sound decisions in all of these areas. Women who are denied abortions are measurably worse off than women who receive a wanted abortion—in measures of economic security, the well-being of their children, and the achievement of aspirational plans including having future children when they have more support.”

For the women who weren’t able to get abortions, the study found that five years later, they had four times greater odds of living below the federal poverty level, were more likely to experience serious complications from the end of pregnancy, including eclampsia and death, were more likely to stay tethered to abusive partners, were more likely to suffer from anxiety and loss of self-esteem in the short term after being denied abortion, and were less likely to have aspirational life plans for the coming year, a release says.

“Legislators who try to make abortion less accessible need to realize there are real harms from forcing women to carry unwanted pregnancies to term,” Foster says. “It affects women’s physical health, the health and security of their families, and the well-being of the next generation.”

Taking antibiotics can have permanent effects on the good bacteria in your digestive system

While antibiotics are helpul for treating bacterial infections, we now know that they do more than kill the pathogenic bacteria we’re targeting. They also affect the millions of microbes living in our digestive tract that are crucial for human health.

A new paper published in Nature Microbiology looked at exactly what happens to gut bacteria after antibiotic use. 12 healthy young men were given a combination of three antibiotics, and then had their microbiomes examined for six months using DNA sequencing to detect bacteria and the genes present in the bacteria.

They found that in six months, the microbiome had almost completely restored itself, in a gradual process similar to plants regrowing after a forest fire, says Sofia Forslund, a group leader at the Max Delbrück Center for Molecular Medicine in Berlin.

After one and half months, the subjects had close to their original microbiome makeup, but the bacteria that came back first, like E nterococcus faecalis and Fusobacterium nucleatum, had more potential to cause infection. Meanwhile, nine common species that all the subjects had before the treatment remained unseen about 180 days later.

At the end of six months, it seemed that some bacteria were lost permanently, including several beneficial bacteria that are associated with better pathogen resistance and metabolic health. The team will now focus on the effects of longer-term antibiotics.

“We need to be aware that a single severe (and perhaps multiple lesser) antibiotic treatments can deplete the gut of some beneficial bacteria, and we should expect an initial bloom of opportunistic pathogens after treatment,” Forslund says. “Better methods for preventing this are needed.”

Your weekly health and science reading list

Losing Laura. By Peter DeMarco in The Boston Globe.

A devastating story of how DeMarco’s wife died from an asthma attack right outside an emergency room’s door.

Why Are Pelvic Exams on Unconscious, Unconsenting Women Still Part of Medical Training? By Phoebe Friesen in Slate.

“Unsurprisingly, 100 percent of women say they would prefer to be asked before their pelvis is used as a teaching tool.”

What if the Placebo Effect Isn’t a Trick? By Gary Greenberg in The New York Times Magazine.

The placebo effect isn’t just in your head—it causes real biological changes. Can we harness them as medicine?

Actually, You Can Just Drink Some Water. By Amanda Mull in The Atlantic.

On the latest Instagram wellness trend: celery juice. “As far as hydration goes, most of celery juice’s proponents cite solid celery’s 95 percent water composition as a way of proving the juiced version’s promise. Regular water is 100 percent water.”