Couples about to tie the knot shouldn't ignore nagging doubts about getting married, warns a University of Alberta researcher.

"If you are having doubts about the relationship, just ignoring them may make a difference years down the road," said Matthew Johnson who co-authored the study while at Kansas State University. Johnson is now an assistant professor in the University of Alberta Department of Human Ecology.

The study, published recently in the journal Family Process, found that couples who were more confident as they exchanged vows also spent more time together 18 months into the marriage, and were still happy sharing life with their spouses at the three-year mark.

The study used existing research data to weigh the marital confidence of 610 newlywed couples over a period of four years. Those who were most confident at the outset of matrimony were still showing their happiness by sticking together as a couple after the honeymoon was long over.

"Nature teaches beasts to know their friends," wrote Shakespeare. In humans, nature may be less than half of the story, a team led by University of Colorado Boulder researchers has found.

In the first study of its kind, the team found that genetic similarities may help to explain why human birds of a feather flock together, but the full story of why people become friends "is contingent upon the social environment in which individuals interact with one another," the researchers write.

People are more likely to befriend genetically similar people when their environment is stratified, when disparate groups are discouraged from interacting, the study found. When environments were more egalitarian, friends were less likely to share certain genes.

Scientists debate the extent to which genetics or environmental factors -- "nature" or "nurture" -- predict certain behaviors, said Jason Boardman, associate professor of sociology and faculty research associate with the Population Program in CU-Boulder's Institute of Behavioral Science. "For all the social demographic outcomes we care about, whether it's fertility, marriage, migration, health, it's never nature or nurture.

"It's always nature and nurture," he said. "And most of the time it has a lot more to do with nurture."

Boardman's team included Benjamin Domingue, research associate in the Population Program at IBS; and Jason Fletcher, associate professor of health policy at the Yale School of Public Health. Their research was recently published in the Proceedings of the National Academy of Sciences.

The psychopath's fearlessness and focus has traditionally been attributed to deficits in emotional processing, more specifically to amygdala dysfunction. Until recently, this has led researchers to believe that in addition to not "doing" fear, they don't "do" empathy, either. But a 2008 study, by Shirley Fecteau and her colleagues at the Beth Israel Deaconess Medical Center in Boston, has thrown a completely different light on the matter, suggesting that psychopaths not only have the capacity to recognize emotions - they are, in fact, actually better at it than we are.

Fecteau and her co-workers used transcranial magnetic stimulation (TMS) to stimulate the somatosensory cortex (the part of the brain that processes and regulates physical sensations) in the brains of volunteers scoring high on the Psychopathic Personality Inventory (PPI). Previous research has shown that observing something painful happening to someone else results in a temporary slowdown in neural excitation in response to TMS, in the area of the somatosensory cortex corresponding to the region afflicted by the pain: the work of highly specialized, and aptly named, brain structures called mirror neurons.

Using optogenetics, McGovern neuroscientists identify a brain region that can switch between new and old habits. Habits are behaviors wired so deeply in our brains that we perform them automatically. This allows you to follow the same route to work every day without thinking about it, liberating your brain to ponder other things, such as what to make for dinner.

However, the brain's executive command center does not completely relinquish control of habitual behavior. A new study from MIT neuroscientists has found that a small region of the brain's prefrontal cortex, where most thought and planning occurs, is responsible for moment-by-moment control of which habits are switched on at a given time.

"We've always thought - and I still do - that the value of a habit is you don't have to think about it. It frees up your brain to do other things," says Institute Professor Ann Graybiel, a member of the McGovern Institute for Brain Research at MIT. "However, it doesn't free up all of it. There's some piece of your cortex that's still devoted to that control."

The new study offers hope for those trying to kick bad habits, says Graybiel, senior author of the new study, which appears this week in the Proceedings of the National Academy of Sciences. It shows that though habits may be deeply ingrained, the brain's planning centers can shut them off. It also raises the possibility of intervening in that brain region to treat people who suffer from disorders involving overly habitual behavior, such as obsessive-compulsive disorder.

Lead author of the paper is Kyle Smith, a McGovern Institute research scientist. Other authors are recent MIT graduate Arti Virkud and Karl Deisseroth, a professor of psychiatry and behavioral sciences at Stanford University.

Independent of a watch or the sun's position in the sky, humans somehow can figure out how much time has ticked by, and a new study reveals how. The study suggests the brain has no master clock, but instead that every individual brain circuit can learn to tell time.

"People think when you need to time something, that there's some clock circuit in the brain that we look to," said study co-author Geoffrey Ghose, a University of Minnesota neuroscientist.

"What our study indicates is it's actually very different. For every little task or every little action or decision you make, you could potentially develop timing representations."

A sense of time is fundamental to living creatures, Ghose told LiveScience.

"Often, you use external cues and events to figure out what time it is, like looking outside and seeing where the sun is or looking at a clock," Ghose said. "But you have a sense of time that's independent of all of that."

How many times have you heard someone say that to you? Angry? "Take a breath." Confused? "Take a breath." Frustrated? "Take a breath." I think this is one of the greatest things we can do for our own mental and physical health. But how do you remember to take a breath when you're angry, confused or frustrated?

I've been teaching myself and others for more than 50 years, and in that time, a sort of user's manual for living a life on the earth has formed in my mind. I've spoken in thousands of seminars, written more books than I can count, and now here's this blog: a distillation of useful suggestions for living a life that fully expresses who each of us is.

OK, how do you remember to breathe? And why should you have to remember - isn't it automatic? Like you, in times of stress I habitually hold my breath when I'd be better off putting my attention there rather than on what's bothering me. Focusing on my breath helps me relax so I can choose the next thing I need to do to handle the stress.

Researchers are looking for a scientific answer to explain why children think they actually disappear when they cover their eyes while playing peekaboo.

Researchers led by James Russell at the University of Cambridge have carried out the first study into this bizarre trait with groups of three and four-year-old children.

The children's eyes were covered with masks and they were then asked whether they could be seen by the researchers - with most saying no.

Many also believed that the researchers could not see adults who were wearing eye masks - leading to the conclusion most young children believe that anyone who covers their eyes is obscured from other people's view.

© Chris ReaumeThis shows a fruit fly feeding. A genetic study by evolutionary biologists at the University of Toronto using fruit flies (Drosophila melanogaster) showed that chronic food deprivation and lack of adequate nutrition in early life had significant impact on adult behavior and quality of life.

Study part of growing body of knowledge surrounding gene-environment interplay.

It is time to put the nature versus nurture debate to rest and embrace growing evidence that it is the interaction between biology and environment in early life that influences human development, according to a series of studies recently published in a special edition of the Proceedings of the National Academy of Sciences (PNAS).

"Biologists used to think that our differences are pre-programmed in our genes, while psychologists argued that babies are born with a blank slate and their experience writes on it to shape them into the adults they become. Instead, the important question to be asking is, 'How is our experience in early life getting embedded in our biology?'" says University of Toronto behavioural geneticist Marla Sokolowski. She is co-editor of the PNAS special edition titled "Biological Embedding of Early Social Adversity: From Fruit Flies to Kindergarteners" along with professors Tom Boyce (University of British Columbia) and Gene Robinson (University of Illinois).

Sokolowski, who is a University Professor in the Department of Ecology & Evolutionary Biology (EEB), the inaugural academic director of Uof T's Fraser Mustard Institute for Human Development and co-director of the Experience-based Brain and Biological Development Program (EBBD) at the Canadian Institute for Advanced Research (CIFAR) says that relatively little is known about the gene-environment interplay that underlies the impact of early life adversity on adult health and behaviour.

Vulnerability to major depression is linked with how satisfied we are with our lives. This association is largely due to genes.

This is the main finding of a new twin study from the Norwegian Institute of Public Health in collaboration with the University of Oslo. The researchers compared longitudinal information from identical and fraternal twins to determine how vulnerability to major depression is associated with dispositional (overall) lifetime satisfaction.

Previous studies have systematically shown that life satisfaction is considerably stable over time. People who are satisfied at any one point in life are often also satisfied at other times in their lives. This stability - the dispositional life satisfaction - is often said to reflect an underlying positive mood or a positive disposition. Previous studies have also shown that people with such a positive disposition are less depressed, but very few studies have examined the mechanisms behind this relationship.

There are few more fascinating and mind-bending frontiers in fields of neuroscience and psychology than the study of how the brain perceives time. While symphonies, stock markets and our daily schedules are conveniently constructed around the well-defined, predictable progression of what might be called 'objective time', our brains take a much more flexible approach to dealing with passing events, stretching, condensing and generally distorting our perception of time in response to a variety of external and internal factors.

In fact, brain time - or our mind's perception of time - is an inherently subjective phenomenon. And it is perhaps never more subjective than when we are confronted with events that bring about a strong emotional response. Numerous studies in recent decades have repeatedly highlighted the fact that both our spatial perception and time perception can be measurably affected by negative or positive emotional experiences.

For instance, study subjects who are shown images that the brain associates with intensely positive experiences - like, say, erotic scenes - will consistently report that these images flit by more quickly than intensely negative pictures such as a grisly murder scene, even when both images are displayed for the exact same length of time.

"We imagine that we're perfect at judging time, but we're not," says Simona Buetti, a postdoctoral researcher in psychology at the University of Illinois at Urbana-Champaign. "If you see a disgusting image, like a photo of a mutilated body, you will perceive this image lasting longer than if you see a picture of people on a roller coaster, or an erotic image."

Buetti and her colleague Alejandro Lleras recently set out to see if they could offset the brain's tendency to distort time in emotionally intense situations. The results of their study, published in the online journal Frontiers in Psychology, demonstrate that this stretching and shortening of perceived time can be corrected simply by making a person feel that they are in control of the situation.