Posts tagged psychology

A study from Karolinska Institutet shows, that our imagination may affect how we experience the world more than we perhaps think. What we imagine hearing or seeing ‘in our head’ can change our actual perception. The study, which is published in the scientific journal Current Biology, sheds new light on a classic question in psychology and neuroscience - about how our brains combine information from the different senses.

"We often think about the things we imagine and the things we perceive as being clearly dissociable," says Christopher Berger, doctoral student at the Department of Neuroscience and lead author of the study. "However, what this study shows is that our imagination of a sound or a shape changes how we perceive the world around us in the same way actually hearing that sound or seeing that shape does. Specifically, we found that what we imagine hearing can change what we actually see, and what we imagine seeing can change what we actually hear."

The study consists of a series of experiments that make use of illusions in which sensory information from one sense changes or distorts one’s perception of another sense. Ninety-six healthy volunteers participated in total. In the first experiment, participants experienced the illusion that two passing objects collided rather than passed by one-another when they imagined a sound at the moment the two objects met. In a second experiment, the participants’ spatial perception of a sound was biased towards a location where they imagined seeing the brief appearance of a white circle. In the third experiment, the participants’ perception of what a person was saying was changed by their imagination of a particular sound.

According to the scientists, the results of the current study may be useful in understanding the mechanisms by which the brain fails to distinguish between thought and reality in certain psychiatric disorders such as schizophrenia. Another area of use could be research on brain computer interfaces, where paralyzed individuals’ imagination is used to control virtual and artificial devices.

"This is the first set of experiments to definitively establish that the sensory signals generated by one’s imagination are strong enough to change one’s real-world perception of a different sensory modality", says Professor Henrik Ehrsson, the principle investigator behind the study.

(Source: ki.se)

The day of the big barbecue arrives and it’s time to fire up the grill. But rather than toss the hamburgers and hotdogs haphazardly onto the grate, you wait for the heat to reach an optimal temperature, and then neatly lay them out in their apportioned areas according to size and cooking times. Meanwhile, your friend is preparing the beverages. Cups are grabbed face down from the stack, turned over, and – using the other hand – filled with ice.

While these tasks – like countless, everyday actions – may seem trivial at first glance, they are actually fairly complex, according to Robrecht van der Wel, an assistant professor of psychology at Rutgers–Camden. “For instance, the observation that you grab a glass differently when you are filling a beverage than when you are stacking glasses suggests that you are thinking about the goal that you want to achieve,” he says. “How do you manipulate the glass? How do you coordinate your actions so that the liquid goes into the cup?  These kinds of actions are not just our only way to accomplish our intentions, but they reveal our intentions and mental states as well.”

van der Wel and his research partners, Marlene Meyer and Sabine Hunnius, turned their attention to how action planning generalizes to collaborative actions performed with others in a study, titled Higher-order planning for individual and joint object manipulations, published recently in Experimental Brain Research.

According to van der Wel, the researchers were especially interested in determining whether people’s actions exhibit certain social capabilities when performing multiple-action sequences in concert with a partner. “It is a pretty astonishing ability that we, as people, are able to plan and coordinate our actions with others,” says van der Wel. “If people plan ahead for themselves, what happens if they are now in a task where their action might influence another person’s comfort? Do they actually take that into account or not, even though, for their personal action, it makes no difference?”

In the research study, participants first completed a series of individual tasks requiring them to pick up a cylindrical object with one hand, pass it to their other hand, and then place it on a shelf. In the collaborative tasks, individuals picked up the object and handed it to their partner, who placed it on the shelf. The researchers varied the height of the shelf, to test whether people altered their grasps to avoid uncomfortable end postures. The object could only be grasped at one of two positions, implying that the first grasp would determine the postures – and comfort – of the remaining actions.

According to the researchers, the results from both the individual and joint performances show that participants altered their grasp location relative to the height of the shelf.  The participants in both scenarios were thus more likely to use a low-grasp location when the shelf was low, and vice versa. Doing so implied that the participants ended the sequences in comfortable postures. The researchers conclude that, in both individual and collaborative scenarios, participants engaged in extended planning to finish the object-transport sequences in a relatively comfortable posture. Given that participants did plan ahead for the sake of their action partner, it indicates an implicit social awareness that supports collaboration across individuals.

van der Wel notes that, while such basic actions may seem insignificant, it is important to understand how people perform basic tasks such as manipulating objects when considering those populations that aren’t able to complete them so efficiently. “How to pick up an object seems like a really trivial problem when you look at healthy adults, but as soon as you look at children, or people suffering from a stroke, it takes some time to develop that skill properly,” says van der Wel. “When someone has a stroke, it is not that they have damage to the musculature involved in doing the task; rather, damage to action planning areas in the brain results in an inability to perform simple actions. A better understanding of the mechanisms involved in action planning may guide rehabilitation strategies in such cases.”

According to van der Wel, the researchers are currently working on modifying the task to determine the age at which children begin planning their actions with respect to other peoples’ comfort. In particular, they want to understand how the development of social action planning links with the development of other cognitive and social abilities.

(Source: news.rutgers.edu)

New work at the University of California, Davis, shows for the first time how visual attention affects activity in specific brain cells. The paper, published June 26 in the journal Nature, shows that attention increases the efficiency of signaling into the brain’s cerebral cortex and boosts the ratio of signal over noise.

It’s the first time neuroscientists have been able to look at the behavior of synaptic circuits at such a fine-grained level of resolution while measuring the effects of attention, said Professor Ron Mangun, dean of social sciences at UC Davis and a researcher at the UC Davis Center for Mind and Brain.

Our brains recreate an internal map of the world we see through our eyes, mapping our visual field onto specific brain cells. Humans and our primate relatives have the ability to pay attention to objects in the visual scene without looking at them directly, Mangun said.

"Essentially, we ‘see out of the corner of our eyes,’ as the old saying goes. This ability helps us detect threats, and react quickly to avoid them, as when a car running a red light at high speed is approach from our side," he said.

Postdoctoral scholar Farran Briggs worked with Mangun and Professor Martin Usrey at the UC Davis Center for Neuroscience to measure signaling through single nerve connections, or synapses, in monkeys while they performed a standard cognitive test for attention: pressing a joystick in response to seeing a stimulus appear in their field of view.

By taking measurements on each side of a synapse leading into the cerebral cortex, the team could measure when neurons were firing, the strength of the signal and the signal-to-noise ratio.

The researchers found that when the animals were paying attention to an area within their field of view, the signal strength through corresponding synapses leading into the cortex became more effective, and the signal was boosted relative to background noise.

Combining established cognitive psychology with advanced neuroscience, the technique opens up new possibilities for research.

"There are a lot of questions about attention that we can now investigate, such as which brain mechanisms are disordered in diseases that affect attention," Usrey said.

The method could be used, for example, to probe the cholinergic nervous system, which is impacted by Alzheimer’s disease. It could also help to better understand developmental disorders that involve defects in attention, such as attention deficit hyperactivity disorder and autism.

"It’s going to turn out to be important for understanding and treating all kinds of diseases," Mangun predicted.

(Source: news.ucdavis.edu)

Vision and Hearing Work Together in the Brain to Help Us Catch a Moving Target

A new study has found that chasing down a moving object is not only a matter of sight or of sound, but of mind.

The study found that people who are blindfolded employ the same strategy to intercept a running ball carrier as people who can see, which suggests that multiple areas of the brain cooperate to accomplish the task.

Regardless of whether they could see or not, the study participants seemed to aim ahead of the ball carrier’s trajectory and then run to the spot where they expected him or her to be in the near future. Researchers call this a “constant target-heading angle” strategy, similar to strategies used by dogs catching Frisbees and baseball players catching fly balls.

It’s also the best way to catch an object that is trying to evade capture, explained Dennis Shaffer, assistant professor of psychology at The Ohio State University at Mansfield.

“The constant-angle strategy geometrically guarantees that you’ll reach your target, if your speed and the target’s speed stay constant, and you’re both moving in a straight line. It also gives you leeway to adjust if the target abruptly changes direction to evade you,” Shaffer said.

“The fact that people run after targets at a constant angle regardless of whether they can see or not suggests that there are brain mechanisms in place that we would call ‘polymodal’—areas of the brain that serve more than one form of sensory modality. Sight and hearing may be different senses, but within the brain the results of the sensory input for this task may be the same.”

The study appears in the journal Psychonomic Bulletin and Review.

Nine people participated in the study—mainly students at Ohio State and Arizona State University, where the study took place. Some had experience playing football, either at a high school or collegiate intramural level, while others had limited or no experience with football.

The nine of them donned motion-capture equipment and took turns in pairs, one running a football across a 20-meter field (nearly 22 yards), and one chasing. They randomly assigned participants to sighted and blindfolded conditions. In the blindfolded condition, participants wore a sleep mask and the runner carried a foam football with a beeping device inside, so that the chaser had a chance to locate them by sound. The runners ran in the general direction of the chasers at different angles, and sometimes the runner would cut right or left halfway through the run.

The study was designed so that the pursuer wouldn’t have time to consciously think about how to catch the runner.

“We were just focused on trying to touch the runner as soon as possible and before they exited the field,” Shaffer said. “The idea was to have the strategy emerge by instinct.”

About 97 percent of the time, the person doing the chasing used the constant-angle strategy—even when they were blindfolded and only able to hear the beeping football.

The results were surprising, even to Shaffer.

“I knew that this seemed to be a universal strategy across species, but I expected that people’s strategies would vary more when they were blindfolded, just because we aren’t used to running around blindfolded. I didn’t expect that the blindfolded strategies would so closely match the sighted ones.”

The findings suggest that there’s some common area in the brain that processes sight and sound together when we’re chasing something.

There is another strategy for catching moving targets. Researchers call it the pursuit or aiming strategy, because it involves speeding directly at the target’s current location. It’s how apex predators such as sharks catch prey.

“As long as you are much faster than your prey, the pursuit strategy is great. You just overtake them,” Shaffer said.

In a situation where the competition is more equal, the constant-angle strategy works better—the pursuer doesn’t have to be faster than the target, and if the target switches direction, the pursuer has time to adjust.

The study builds on Shaffer’s previous work with how collegiate-level football players chase ball carriers. He’s also studied how people catch baseballs and dogs catch Frisbees. All appear to use strategies similar to the constant target-heading angle strategy, which suggests that a common neural mechanism could be at work.

(Source: researchnews.osu.edu)

UC Berkeley researchers have found that a lack of sleep, which is common in anxiety disorders, may play a key role in ramping up the brain regions that contribute to excessive worrying.

Neuroscientists have found that sleep deprivation amplifies anticipatory anxiety by firing up the brain’s amygdala and insular cortex, regions associated with emotional processing. The resulting pattern mimics the abnormal neural activity seen in anxiety disorders. Furthermore, their research suggests that innate worriers – those who are naturally more anxious and therefore more likely to develop a full-blown anxiety disorder – are acutely vulnerable to the impact of insufficient sleep.

“These findings help us realize that those people who are anxious by nature are the same people who will suffer the greatest harm from sleep deprivation,” said Matthew Walker, a professor of psychology and neuroscience at UC Berkeley and senior author of the paper, which was published in the Journal of Neuroscience.

The results suggest that people suffering from such maladies as generalized anxiety disorder, panic attacks and post-traumatic stress disorder, may benefit substantially from sleep therapy. At UC Berkeley, psychologists such as Allison Harvey, a co-author on the Journal of Neuroscience paper, have been garnering encouraging results in studies that use sleep therapy on patients with depression, bipolar disorder and other mental illnesses.

“If sleep disruption is a key factor in anxiety disorders, as this study suggests, then it’s a potentially treatable target,” Walker said. “By restoring good quality sleep in people suffering from anxiety, we may be able to help ameliorate their excessive worry and disabling fearful expectations.”

While previous research has indicated that sleep disruption and psychiatric disorders often occur together, this latest study is the first to causally demonstrate that sleep loss triggers excessive anticipatory brain activity associated with anxiety, researchers said.

“It’s been hard to tease out whether sleep loss is simply a byproduct of anxiety, or whether sleep disruption causes anxiety,” said Andrea Goldstein, a UC Berkeley doctoral student in neuroscience and lead author of the study. “This study helps us understand that causal relationship more clearly.”

In their experiments, performed at UC Berkeley’s Sleep and Neuroimaging Laboratory, Walker and his research team scanned the brains of 18 healthy young adults as they viewed dozens of images, first after a good night’s rest, and again after a sleepless night. The images were either neutral, disturbing or alternated between both.

Participants in the experiments reported a wide range of baseline anxiety levels, but none fit the criteria for a clinical anxiety disorder. After getting a full night’s rest at the lab, which researchers monitored by measuring neural electrical activity, their brains were scanned via functional MRI as they waited to be shown, and then viewed 90 images during a 45-minute session.

To trigger anticipatory anxiety, researchers primed the participants using one of three visual cues prior to each series of images. A large red minus sign signaled to participants that they were about to see a highly unpleasant image, such as a death scene. A yellow circle portended a neutral image, such as a basket on a table. Perhaps most stressful was a white question mark, which indicated that either a grisly image or a bland, innocuous one was coming, and kept participants in a heightened state of suspense.

When sleep-deprived and waiting in suspenseful anticipation for a neutral or disturbing image to appear, activity in the emotional brain centers of all the participants soared, especially in the amygdala and the insular cortex. Notably, the amplifying impact of sleep deprivation was most dramatic for those people who were innately anxious to begin with.

“This discovery illustrates how important sleep is to our mental health,” said Walker. “It also emphasizes the intimate relationship between sleep and psychiatric disorders, both from a cause and a treatment perspective.”

(Source: newscenter.berkeley.edu)

Breastfeeding not only boosts children’s chances of climbing the social ladder, but it also reduces the chances of downwards mobility, suggests a large study published online in the Archives of Disease in Childhood.

The findings are based on changes in the social class of two groups of individuals born in 1958 (17,419 people) and in 1970 (16,771 people).

The researchers asked each of the children’s mums, when their child was five or seven years old, whether they had breastfed him/her.

They then compared people’s social class as children - based on the social class of their father when they were 10 or 11 - with their social class as adults, measured when they were 33 or 34.

Social class was categorised on a four-point scale ranging from unskilled/semi-skilled manual to professional/managerial.

The research also took account of a wide range of other potentially influential factors, derived from regular follow-ups every few years. These included children’s brain (cognitive) development and stress scores, which were assessed using validated tests at the ages of 10-11.

Significantly fewer children were breastfed in 1970 than in 1958. More than two-thirds (68%) of mothers breastfed their children in 1958, compared with just over one in three (36%) in 1970.

Social mobility also changed over time, with those born in 1970 more likely to be upwardly mobile, and less likely to be downwardly mobile, than those born in 1958.

None the less, when background factors were accounted for, children who had been breastfed were consistently more likely to have climbed the social ladder than those who had not been breastfed. This was true of those born in both 1958 and 1970.

What’s more, the size of the “breastfeeding effect” was the same in both time periods. Breastfeeding increased the odds of upwards mobility by 24% and reduced the odds of downward mobility by around 20% for both groups.

Intellect and stress accounted for around a third (36%) of the total impact of breastfeeding: breastfeeding enhances brain development, which boosts intellect, which in turn increases upwards social mobility. Breastfed children also showed fewer signs of stress.

The evidence suggests that breastfeeding confers a range of long-term health, developmental, and behavioural advantages to children, which persist into adulthood, say the authors.

They note that it is difficult to pinpoint which affords the greatest benefit to the child - the nutrients found in breast milk or the skin to skin contact and associated bonding during breastfeeding.

“Perhaps the combination of physical contact and the most appropriate nutrients required for growth and brain development is implicated in the better neurocognitive and adult outcomes of breastfed infants,” they suggest.