It's a cliché that men just don't understand women.

Now, new research suggests men really do struggle to read women's emotions — at least from their eyes.

The research, published Wednesday (April 10) in the journal  PLOS ONE, showed that men had twice as much trouble deciphering women's emotions from images of their eyes compared with those of men. Parts of the male brain tied to emotion also didn't activate as strongly when the men looked at women's eyes.

While pop culture claims that men are from Mars and women are from Venus, both sexes are pretty similar. Yet despite the genders' psychological overlap, a few small studies in men have suggested they have trouble "mind-reading" and guessing what women are thinking and feeling. For instance, one study found that  men interpret friendliness from women as sexual  come-ons. [ Busted! 6 Gender Myths in the Bedroom & Beyond ]

 Research also shows that women prize men who try to understand them.

To see whether men really did have trouble reading women's emotions, Boris Schiffer, a researcher at the LWL-University Hospital in Bochum, Germany and his colleagues put 22 men between the ages of 21 and 52, with an average age of 36, in a functional magnetic resonance imaging scanner, which uses blood flow as a measure of  to measure their brain activity.

They then asked the men to look at images of 36 pairs of eyes, half from men and half from women, and guess the emotion the people felt. The men then chose which of two words, such as distrustful or terrified, best described the eyes' emotion. The eye photographs depicted positive, neutral, and negative emotions.

Men took longer and had more trouble correctly guessing emotion from women's eyes.

In addition, their brains showed different activation when looking at men versus women's eyes. Men's amygdala — a brain region tied to emotions, empathy, and fear — activated more strongly in response to men's eyes. In addition, other brain regions tied to emotion and behavior didn't activate as much when the men looked at women's eyes.

The findings suggest that men are worse at reading women's emotions. This "theory of mind" is one of the foundations for empathy, so the deficit could lead men to have less empathy for women relative to men, the researchers write.

But exactly why this happens isn't clear. While men could be culturally conditioned to pay less attention to women's emotional cues, another possibility is that their differential response is hard-wired by humans' evolutionary past.

"As men were more involved in hunting and territory fights, it would have been important for them to be able to predict and foresee the intentions and actions of their male rivals," the researchers write in the paper.

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Contrary to popular diet advice, chewing gum may not help people eat less or lose weight, new research suggests.

In fact, the study, published in the April issue of the journal Eating Behaviors, suggests that chewing gum may lead people to eat chips, cookies and candy instead of fruits and veggies. That's because menthol, the chemical responsible for the minty-fresh flavor of some types of gum makes fruits and veggies taste funny.

The chemical change is the same reason why "when you brush your teeth and then drink orange juice, it tastes bad," said study co-author Christine Swoboda, a doctoral candidate in nutrition at Ohio State University.

Chewing gum can aid test performance, and xylitol-sweetened gum may reduce ear infections in children.

And because it may evoke thoughts of food and get digestive juices flowing, some people hypothesized that chewing gum could make people hungrier. But scientists have also hypothesized the opposite — that the act of chewing could make people feel more full and, in turn, eat less. To test that claim, the gum manufacturer Wrigley even offers grants for scientific research on the subject. [ The 7 Biggest Diet Myths Debunked ]

But despite claims to the contrary, only a few studies have looked at whether chewing gum aids weight loss, and these have found conflicting results, Swoboda said.

"We were interested in seeing 'Does this really help with weight loss?'" Swoboda told LiveScience.

To find out, Swoboda and colleague Jennifer Temple of the University at Buffalo asked 44 volunteers to play a slotmachine-style game in exchange for food. Some of the participants played for mandarin oranges or grapes, while others played for potato chips or M&Ms.

Prior to playing the game, half of the participants chewed either Juicy Fruit gum or Wrigley's Spearmint gum.

Those who chewed the minty gum were significantly less likely to play as long for the fruit, suggesting they were less motivated to get them when chewing gum. The fruity gum showed a smaller effect that wasn't statistically significant.

In a second experiment, the researchers asked participants to keep a food journal recording what they ate. Some of the time, the participants were asked to chew a mint green-tea gum before every meal and snack for a week, while other times, they simply had to record their food intake.

When chewing gum, participants ate fewer meals. But that didn't translate into fewer calories: Instead, people were actually getting fewer nutrients in their diet and about the same amount of calories.

It could be that the menthol in mint, which interacts with nutrients in fruits and veggies to create a bitter flavor, was turning people off to the healthy foods, Swoboda said.

People "ate less fruits and vegetables, because in their head, they thought 'I have to chew gum before every meal — do I really want a snack of grapefruit?'" she said. "Whereas, they were like, 'I'm so hungry I'm going to eat this double cheeseburger and it will taste the same.'"

The findings are interesting, but they don't reveal how gum might change people's eating habits in the long run, said Brett Carter, a food behavior researcher at the University of Washington in Seattle, who was not involved in the study.

In addition, using food diaries is a notoriously inaccurate measure of calories, Carter added.

"As you can imagine people aren't very good at keeping track of exactly how they eat," Carter told LiveScience. "Translating it to calories can lend itself to a lot of error."

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Brain
As you hear a punch line, your brain ignites its centers for higher thought, muscle function, and emotion. Their conclusion: What a riot! The muscles around your eyes and cheeks start spontaneously contracting.

Your noggin shoots a signal to your brain stem, the body's HQ for lung functions like breathing and laughter.

Lungs
Your diaphragm and chest muscles tighten, forcing air out of your lungs. That air rushes through your windpipe, blowing over your larynx. Your vocal cords vibrate and emit short, unfettered vowel sounds like ha-ha or ho-ho.

Eyes
If what has you going is really funny, your eyes start to water.

Heart
The sudden exit of air from your lungs creates an urgent call for oxygen. Your heart rate and blood pressure ramp up to help ferry more O2 to your organs.

Muscles
While facial and core muscles tense, the rest of your muscles become weaker or less coordinated. Hence, it can feel impossible to walk straight while laughing hard.

Your obliques are also working to help expel air. You may burn a few extra calories.

Hormones
A side-splitting laugh can help release endorphins, those natural opiates often triggered by exercise. Your pain threshold might shoot up, at least temporarily.

Loads of chuckling may also dial down production of the stress hormone cortisol--a happy thing, since too much cortisol has been linked to exhaustion and depression.

Emotions
It's true: Laughter is contagious. Some scientists speculate it evolved as an early bonding mechanism. If they're right, sharing a laugh with someone could help the two of you connect emotionally.

Sources: Donald Casadonte, D.M.A., and Dianne Fidelibus, P.C., Columbus State Community College; Robin Dunbar, Ph.D., University of Oxford; Peter McGraw, Ph.D., University of Colorado at Boulder; Willibald Ruch, Ph.D., University of Zurich

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Doing a good deed can lead some people to more kind acts while spurring others to backslide. But how people respond depends on their moral outlook, according to a new study.

People who believe the ends justify the means are likelier to offset good deeds with bad ones and vice versa. By contrast, those who believe right and wrong are defined by principle, not outcome, tend to be more consistent, even if they're behaving unethically.

The findings were published Feb. 27 in the journal Psychological Science.

Some studies show that people maintain a kind of moral equilibrium, meaning that giving money to charity may lead them to skimp on the tip at dinner, whereas partying too much may inspire a volunteer day at the soup kitchen.

But other studies found just the opposite: Behaving ethically leads people to more good deeds later, said study co-author, Gert Cornelissen, a psychologist at the University Pompeu Fabra in Spain.

To sort out this conflicting picture, Cornelissen and his colleagues asked 84 undergraduates what they would do in a hypothetical dilemma where a runaway trolley is on a collision course with five people, and the only way to save them is to flip a switch, reroute the trolley and kill one person. 

People who would flip the switch were considered to have outcome-based morality, where the end results (saving four lives), not the actions (causing one person's death), matter most. Those in the opposite group were assumed to base their morality on rules, such as "deliberate killing is always wrong."

Half of the participants were then asked to remember a time they behaved ethically, while the other group remembered past unethical behavior. They then asked participants to share a pot of money with partners.  

Those who had an ends-justify-the-means mindset were likelier to be stingier with others if they were reminded of their past good deeds and more generous if they recalled past unethical behavior. By contrast, those who tended towards rules-based morality showed the opposite trend, suggesting that past good deeds or bad deeds were prompting similar behavior later on.

In another experiment, students showed the same trends in their likeliness to cheat on a self-graded quiz. Consistent with that trend, remembering past  bad deeds made people with rule-based morality more likely to cheat.

For people who are keeping a mental balance sheet of their good and bad deeds, one bad act can be an offset in their minds with a nice one, Cornelissen said.

But for those with rule-based morality, that bad deed can cause a slippery slope, Cornelissen said.

"When people are thinking in terms of rules, they think once a rule is broken, the harm is done, so it's very difficult to undo that, the stain remains," Cornelissen told LiveScience. "The more efficient way for people in that case to feel is to convince themselves that whatever wrong they did is not that bad."

Once that's the case, it's easier for them to behave unethically in the future, he said.

Of course in real life, most people have a messier moral approach, mixing outcome-based morality with firm principles in different areas of their lives, he said.

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Men are from Mars and women are from Venus? Think again. New research suggests that black-and-white thinking about what makes a man and what makes a woman is off-base.

In fact, while real gender differences (whether biologically based or cultural) do exist, men and women overlap psychologically more than they differ, according to a new study published in February in the Journal of Personality and Social Psychology. In other words, cute book titles aside, both genders are from Earth.

"Sex is not nearly as confining a category as stereotypes and even some academic studies would have us believe," study researcher Bobbi Carothers, a senior data analyst at Washington University in St. Louis, said in a statement.

Carothers, who completed the research as part of her doctoral dissertation at the University of Rochester, and her colleagues are not denying that men and women often do differ from one another. Women, for example, are known to have higher levels of anxiety than men, on average, and to react to bad news with more stress. Studies also turn up gender differences in aggression, sexuality, frequency of smiling, and body image, Carothers and her colleagues wrote.

But researchers haven't spent much time examining the structure of these differences, Carothers wrote. It's possible, for example, that men and women usually fall into distinct groups. In this categorical world, knowing someone is a man would automatically tell you that he's aggressive, interested in short-term sex over long-term relationships, good at math and bad verbally. Alternatively, gender differences could occur more often on a continuum. You might know someone is a man, but it would tell you little about his skills with math. [ Busted! 6 Gender Myths in the Bedroom and Beyond ]

Which possibility is more likely might seem clear to anyone who has ever known a guy who can't figure out a tip to save his life. But humans tend toward categorical thinking, the researchers wrote, and gender is about as basic a category as you can get. That may explain self-help books, such as "Men Are from Mars, Women Are from Venus" (HarperCollins, 1992), which posit the genders as so different that they can barely communicate — at least not without the help of a guidebook.

"'Boy or girl?' is the first question parents are asked about their newborn, and sex persists through life as the most pervasive characteristic used to distinguish categories among humans," the researchers wrote.

To look at the question statistically, Carothers and her colleagues contacted researchers who had done gender-difference studies and asked for their raw data. They gathered data on 13,301 individuals who had participated in 13 different studies looking at 122 behavioral and personality factors that might differ between genders.

The researchers then crunched all the numbers to find out if differences fell into categorical patterns or on a continuum.

They found some categorical differences. There was little overlap between male and female physical strength, for example. Likewise, weight, height and arm circumference fell into largely distinct groups for men and women. So did activities specifically chosen as sex-stereotypical. Turns out that it's true that men aren't that crazy about scrapbooking, and not that many gals get into boxing.

But on psychological measures, gender is a gray area. Men and women fell along a continuum on such measures as interest in casual sex, frequency of thoughts about sex, and the appeal of certain traits such as virginity, looks and wealth in a mate. The same was true of attitudes toward close relationships, empathy and other interpersonal factors.

In other words, if told that a person is more than 6 feet tall, you would be pretty safe in guessing that they were a guy. If told that a person is very empathic, you'd be much harder-pressed to correctly guess their gender.

Personality traits such as extroversion and openness to new experience also fell along a continuum, as did stereotypically masculine and feminine personality traits such as caregiving, self-sacrifice and desire for justice. Interest and talent in science also fell along a continuum, despite stereotypes that men are better.

Nor did the supposed "masculine" and "feminine" traits stick together, the authors wrote. A man high in aggression is no more likely to be better at math than a man low in aggression.

The data from the studies used reaches back years, when gender roles were not as fluid as they are today, the authors wrote. That strengthens the argument for a gender continuum, they said, because gender differences show up as flexible even when gender stereotypes were stronger.

Whether gender differs on a discrete or a continual scale may seem an academic question. But how people think of the opposite sex can directly influence human relationships, said Harry Reis, a University of Rochester psychologist and a co-researcher on the study. [ 6 Scientific Tips for a Successful Marriage ]

"When something goes wrong between partners, people often blame the other partner's gender immediately," Reis said in a statement. "Having gender stereotypes hinders people from looking at their partner as an individual. They may also discourage people from pursuing certain kinds of goals. When psychological and intellectual tendencies are seen as defining characteristics, they are more likely to be assumed to be innate and immutable. Why bother to try to change?"

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On a scale of one to 10, you probably think you're a seven. And you wouldn't be alone.

While it's impossible for most people to be above the median for a specific quality, people think they are better than most people in many arenas, from charitable behavior to work performance.

The phenomenon, known as illusory superiority, is so stubbornly persistent that psychologists would be surprised if it didn't show up in their studies, said David Dunning, a psychologist at Cornell who has studied the effect for decades.

It happens for many reasons: Others are too polite to say what they really think, incompetent people lack the skills to assess their abilities accurately, and such self-delusions can actually protect people's mental health, Dunning told LiveScience.

Since psychological studies first began, people have given themselves top marks for most positive traits. While most people do well at assessing others, they are wildly positive about their own abilities, Dunning said.

That's because we realize the external traits and circumstances that guide other people's actions, "but when it comes to us, we think it's all about our intention, our effort, our desire, our agency — we think we sort of float above all these kinds of constraints," he said. [ 10 Things You Didn't Know About You ]

In studies, most people overestimate their IQ. For instance, in a classic 1977 study, 94 percent of professors rated themselves above average relative to their peers. In another study, 32 percent of the employees of a software company said they performed better than 19 out of 20 of their colleagues. And Dunning has found that people overestimate how charitable they'll be in future donation drives, but accurately guess their peers' donations.

Drivers consistently rate themselves as better than average — even when a test of their hazard perception reveals them to be below par, said Mark Horswill, a psychologist at the University of Queensland in Australia.

"You find it across all ages, you find it among novice drivers, and you find it among drivers over age 65," Horswill told LiveScience.

Because even the worst driver may by chance avoid an accident, people are more likely to overestimate skills like that than concrete skills like chess or tennis, where the incompetent are trounced quickly, Horswill said.

In part, most positive traits — like being a good driver — are so vaguely defined that there's plenty of wiggle room to make them fit, Dunning said.  People also don't usually get honest feedback from others.

"People don't say to your face what they might say behind your back," Dunning said.

But in a strange twist, the most incompetent are also the most likely to overestimate their skills, while the ace performers are more likely to underrate themselves, because if they find a skill easy they assume other people do too, he said.

One group seems to be immune to such self-aggrandizement: People who are depressed or have anxiety don't overrate themselves, Horswill said. The more severe the depression, the more likely they are to underrate themselves. That suggests the illusion of superiority may actually be a protective mechanism that shields our self-esteem, he added.

"You think you're better than everyone else and that's actually good for mental health," Horswill said.

And the trend varies considerably with culture.

"North Americans seem to be the kings and queens of overestimation. If you go to places like Japan, Korea or China, this whole phenomenon evaporates," Dunning said.

That is possibly because Eastern cultures value self-improvement, while Western culture tends to value self-esteem, he said.

While it's not possible to get a completely clear-eyed view of oneself, people can bring their self-perception more in line with reality, Dunning said.

For one, people should look to others whose lives inspire admiration, figure out what they're doing right, and try to emulate them, he said.

And since people are generally pretty accurate in assessing other people (just not themselves), people should be aggressive about getting — and taking to heart — constructive criticism from others, he said.

"The road to self-insight runs through other people," he said.

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