Posts tagged multitasking
Articles and news from the latest research reports.
Brain scans reveal ‘grey matter’ differences in media multitaskers
Simultaneously using mobile phones, laptops and other media devices could be changing the structure of our brains, according to new University of Sussex research.
A study published today (24 September) in PLOS ONE reveals that people who frequently use several media devices at the same time have lower grey-matter density in one particular region of the brain compared to those who use just one device occasionally.
The research supports earlier studies showing connections between high media-multitasking activity and poor attention in the face of distractions, along with emotional problems such as depression and anxiety.
But neuroscientists Kep Kee Loh and Dr Ryota Kanai point out that their study reveals a link rather than causality and that a long-term study needs to be carried out to understand whether high concurrent media usage leads to changes in the brain structure, or whether those with less-dense grey matter are more attracted to media multitasking.
The researchers at the University of Sussex’s Sackler Centre for Consciousness Science used functional magnetic resonance imaging (fMRI) to look at the brain structures of 75 adults, who had all answered a questionnaire regarding their use and consumption of media devices, including mobile phones and computers, as well as television and print media.
They found that, independent of individual personality traits, people who used a higher number of media devices concurrently also had smaller grey matter density in the part of the brain known as the anterior cingulate cortex (ACC), the region notably responsible for cognitive and emotional control functions.
Kep Kee Loh says: “Media multitasking is becoming more prevalent in our lives today and there is increasing concern about its impacts on our cognition and social-emotional well-being. Our study was the first to reveal links between media multitasking and brain structure.”
Scientists have previously demonstrated that brain structure can be altered upon prolonged exposure to novel environments and experience. The neural pathways and synapses can change based on our behaviours, environment, emotions, and can happen at the cellular level (in the case of learning and memory) or cortical re-mapping, which is how specific functions of a damaged brain region could be re-mapped to a remaining intact region.
Other studies have shown that training (such as learning to juggle, or taxi drivers learning the map of London) can increase grey-matter densities in certain parts of the brain.
“The exact mechanisms of these changes are still unclear,” says Kep Kee Loh. “Although it is conceivable that individuals with small ACC are more susceptible to multitasking situations due to weaker ability in cognitive control or socio-emotional regulation, it is equally plausible that higher levels of exposure to multitasking situations leads to structural changes in the ACC. A longitudinal study is required to unambiguously determine the direction of causation.”
(Source: sussex.ac.uk)
Targeted brain training may help you multitask better
The area of the brain involved in multitasking and ways to train it have been identified by a research team at the IUGM Institut universitaire de gériatrie de Montréal and the University of Montreal. The research includes a model to better predict the effectiveness of this training. Cooking while having a conversation, watching a movie while browsing the Web, or driving while listening to a radio show – multitasking is an essential skill in our daily lives. Unfortunately, it decreases with age, which makes it harder for seniors to keep up, causes them stress, and decreases their confidence. Many commercial software applications promise to improve this ability through exercises. But are these exercises truly effective, and how do they work on the brain? The team addresses these issues in two papers published in AGE and PLOS ONE.
Targeted Action for a Specific Result
The findings are important because they may help scientists develop better targeted cognitive stimulation programs or improve existing training programs. Specialists sometimes question the usefulness of exercises that may be ineffective simply because they are poorly structured. “To improve your cardiovascular fitness, most people know you need to run laps on the track and not work on your flexibility. But the way targeted training correlates to cognition has been a mystery for a long time. Our work shows that there is also an association between the type of cognitive training performed and the resulting effect. This is true for healthy seniors who want to improve their attention or memory and is particularly important for patients who suffer from damage in specific areas of the brain. We therefore need to better understand the ways to activate certain areas of the brain and target this action to get specific results,” explained Sylvie Belleville, who led the research.
Researchers are now better able to map these effects on the functioning of very specific areas of the brain. Will we eventually be able to adapt the structure of our brains through highly targeted training? “We have a long road ahead to get to that point, and we don’t know for sure if that would indeed be a desirable outcome. However, our research findings can be used right away to improve the daily lives of aging adults as well as people who suffer from brain damage,” Dr. Belleville said.
The Right Combination of Plasticity and Attentional Control
In one of the studies, 48 seniors were randomly allocated to training that either worked on plasticity and attentional control or only involved simple practice. The researchers used functional magnetic resonance imaging to evaluate the impact of this training on various types of attentional tasks and on brain function. The team showed that training on plasticity and attentional control helped the participants develop their ability to multitask. However, performing two tasks simultaneously was not what improved this skill. For the exercises, the research participants instead had to modulate the amount of attention given to each task. They were first asked to devote 80% of their attention to task A and 20% to task B and then change the ratio to 50:50 or 20:80. This training was the only type that increased functioning in the middle prefrontal region, or the area known to be responsible for multitasking abilities and whose activation decreases with age. The researchers used this data to create a predictive model of the effects of cognitive training on the brain based on the subjects’ characteristics.
(Source: eurekalert.org)
Your brain on speed: Walking doesn’t impair thinking and multitasking
When we’re strolling down memory lane, our brains recall just as much information while walking as while standing still—findings that contradict the popular science notion that walking hinders one’s ability to think.
University of Michigan researchers at the School of Kinesiology and the College of Engineering examined how well study participants performed a very complex spatial cognitive task while walking versus standing still.
"We’re saying that at least for this task, which is fairly complicated, walking and thinking does not compromise your thinking ability at all," said Julia Kline, a U-M doctoral candidate in biomedical engineering and first author on the study, which appears online in Frontiers in Human Neuroscience.
The finding surprised researchers, who expected to see decreased thinking performance with increased walking speed, Kline said. The 2011 best-selling book “Thinking Fast and Slow” suggests that because walking requires mental effort, walking may hinder our ability to think when compared to standing still.
"Past studies that have compared mental performance at a slow walking speed and standing have not found any differences, but our study is the first to show that the walking speed doesn’t matter," said Daniel Ferris, professor of kinesiology and biomedical engineering and senior author of the paper.
"Given the health benefits of walking, we should not discourage people from walking and thinking when they want."
Ferris offered one caveat: previous research has shown that walking performance can be impaired in the elderly when they dual-task during gait.
Ferris, Kline and Katherine Poggensee of U-M’s Human Neuromechanics Laboratory measured the ability of young, healthy participants to memorize numbers and their placement on a grid, and then enter those numbers correctly with a keypad while walking different speeds and standing still.
"Think of filling numbers one through nine on a tic-tac-toe grid and then remembering where they all are," Ferris said. "At every walking speed and standing still, participants entered about half the numbers correctly."
While speed didn’t change task performance, people took wider steps when performing the task than when they were only walking, which may be to compensate and stay balanced while concentrating, Kline said.
All participants showed increased activity in areas of the brain associated with spatial relationships and short-term memory during the cognitive task. In keeping with the U-M findings, a recent Stanford study suggested that walking fueled creativity.
In addition to good news for treadmill-desk users or people who like to think on the move, the study provides a useful scientific tool by demonstrating that it’s possible to collect accurate EEG data on moving subjects, Kline said.
This is important to researchers who study the brain and are concerned about getting accurate results when the subjects aren’t perfectly still. U-M researchers achieved their EEG results by applying different signal-processing techniques to eliminate the movement “noise” from the EEG signal.
Female frogs prefer males who can multitask
From frogs to humans, selecting a mate is complicated. Females of many species judge suitors based on many indicators of health or parenting potential. But it can be difficult for males to produce multiple signals that demonstrate these qualities simultaneously.
In a study of gray tree frogs, a team of University of Minnesota researchers discovered that females prefer males whose calls reflect the ability to multitask effectively. In this species (Hyla chrysoscelis) males produce “trilled” mating calls that consist of a string of pulses.
Typical calls can range in duration from 20-40 pulses per call and occur between 5-15 calls per minute. Males face a trade-off between call duration and call rate, but females preferred calls that are longer and more frequent, which is no simple task.
The findings were published in August issue of Animal Behavior.
"It’s kind of like singing and dancing at the same time," says Jessica Ward, a postdoctoral researcher who is lead author for the study. Ward works in the laboratory of Mark Bee, a professor in the College of Biological Sciences’ Department of Ecology, Evolution and Behavior.
The study supports the multitasking hypothesis, which suggests that females prefer males who can do two or more hard-to-do things at the same time because these are especially good quality males, Ward says. The hypothesis, which explores how multiple signals produced by males influence female behavior, is a new area of interest in animal behavior research.
By listening to recordings of 1,000 calls, Ward and colleagues learned that males are indeed forced to trade off call duration and call rate. That is, males that produce relatively longer calls only do so at relatively slower rates.
"It’s easy to imagine that we humans might also prefer multitasking partners, such as someone who can successfully earn a good income, cook dinner, manage the finances and get the kids to soccer practice on time."
The study was carried out in connection with Bee’s research goal, which is understanding how female frogs are able to distinguish individual mating calls from a large chorus of males. By comparison, humans, especially as we age, lose the ability to distinguish individual voices in a crowd. This phenomenon, called the “cocktail party” problem, is often the first sign of a diminishing ability to hear. Understanding how frogs hear could lead to improved hearing aids.
(Source: www1.umn.edu)
Complex brain function depends on flexibility
Over the past few decades, neuroscientists have made much progress in mapping the brain by deciphering the functions of individual neurons that perform very specific tasks, such as recognizing the location or color of an object.
However, there are many neurons, especially in brain regions that perform sophisticated functions such as thinking and planning, that don’t fit into this pattern. Instead of responding exclusively to one stimulus or task, these neurons react in different ways to a wide variety of things. MIT neuroscientist Earl Miller first noticed these unusual activity patterns about 20 years ago, while recording the electrical activity of neurons in animals that were trained to perform complex tasks.
“We started noticing early on that there are a whole bunch of neurons in the prefrontal cortex that can’t be classified in the traditional way of one message per neuron,” recalls Miller, the Picower Professor of Neuroscience at MIT and a member of MIT’s Picower Institute for Learning and Memory.
In a paper appearing in Nature on May 19, Miller and colleagues at Columbia University report that these neurons are essential for complex cognitive tasks, such as learning new behavior. The Columbia team, led by the study’s senior author, Stefano Fusi, developed a computer model showing that without these neurons, the brain can learn only a handful of behavioral tasks.
“You need a significant proportion of these neurons,” says Fusi, an associate professor of neuroscience at Columbia. “That gives the brain a huge computational advantage.”
Lead author of the paper is Mattia Rigotti, a former grad student in Fusi’s lab.
Multitasking neurons
Miller and other neuroscientists who first identified this neuronal activity observed that while the patterns were difficult to predict, they were not random. “In the same context, the neurons always behave the same way. It’s just that they may convey one message in one task, and a totally different message in another task,” Miller says.
For example, a neuron might distinguish between colors during one task, but issue a motor command under different conditions.
Miller and colleagues proposed that this type of neuronal flexibility is key to cognitive flexibility, including the brain’s ability to learn so many new things on the fly. “You have a bunch of neurons that can be recruited for a whole bunch of different things, and what they do just changes depending on the task demands,” he says.
At first, that theory encountered resistance “because it runs against the traditional idea that you can figure out the clockwork of the brain by figuring out the one thing each neuron does,” Miller says.
For the new Nature study, Fusi and colleagues at Columbia created a computer model to determine more precisely what role these flexible neurons play in cognition, using experimental data gathered by Miller and his former grad student, Melissa Warden. That data came from one of the most complex tasks that Miller has ever trained a monkey to perform: The animals looked at a sequence of two pictures and had to remember the pictures and the order in which they appeared.
During this task, the flexible neurons, known as “mixed selectivity neurons,” exhibited a great deal of nonlinear activity — meaning that their responses to a combination of factors cannot be predicted based on their response to each individual factor (such as one image).
Expanding capacity
Fusi’s computer model revealed that these mixed selectivity neurons are critical to building a brain that can perform many complex tasks. When the computer model includes only neurons that perform one function, the brain can only learn very simple tasks. However, when the flexible neurons are added to the model, “everything becomes so much easier and you can create a neural system that can perform very complex tasks,” Fusi says.
The flexible neurons also greatly expand the brain’s capacity to perform tasks. In the computer model, neural networks without mixed selectivity neurons could learn about 100 tasks before running out of capacity. That capacity greatly expanded to tens of millions of tasks as mixed selectivity neurons were added to the model. When mixed selectivity neurons reached about 30 percent of the total, the network’s capacity became “virtually unlimited,” Miller says — just like a human brain.
Mixed selectivity neurons are especially dominant in the prefrontal cortex, where most thought, learning and planning takes place. This study demonstrates how these mixed selectivity neurons greatly increase the number of tasks that this kind of neural network can perform, says John Duncan, a professor of neuroscience at Cambridge University.
“Especially for higher-order regions, the data that have often been taken as a complicating nuisance may be critical in allowing the system actually to work,” says Duncan, who was not part of the research team.
Miller is now trying to figure out how the brain sorts through all of this activity to create coherent messages. There is some evidence suggesting that these neurons communicate with the correct targets by synchronizing their activity with oscillations of a particular brainwave frequency.
“The idea is that neurons can send different messages to different targets by virtue of which other neurons they are synchronized with,” Miller says. “It provides a way of essentially opening up these special channels of communications so the preferred message gets to the preferred neurons and doesn’t go to neurons that don’t need to hear it.”
How Multitasking Can Improve Judgments
Research has revealed that multitasking impedes performance across a variety of tasks. Emergency room nurses that are interrupted multiple times while treating a patient can be more likely to make medication errors. Driving while speaking on a mobile phone significantly increases the probability of an automobile accident. At the same time, however, experienced golfers putt better when distracted than experienced golfers who are focusing on performance. Distractions resulting from the presence of other people can increase an individual’s performance, too. Why?
Addressing the Contradictions
In a forthcoming issue of Psychological Science, one of the world’s top-ranked empirical journals in psychology, a team of researchers from the University of Basel helps to clarify these apparent contradictions. Lead author Janina Hoffmann, a Ph.D. student in Economic Psychology, and her co-authors Dr. Bettina von Helversen and Prof. Dr. Jörg Rieskamp, find that the type of judgment strategy that an individual employs strongly conditions how the “cognitive load” induced by multitasking affects performance. Higher cognitive load can actually improve performance when the task can be best completed using a less demanding, similarity-based strategy that informs judgments by retrieving past instances from memory.
The study is supported by the findings of two experiments conducted at the University of Basel. The first study exposed 90 participants to variable cognitive loads as they were asked to solve a judgment task whose solution was best achieved through the use of a similarity-based strategy (predicting how many cartoon characters another cartoon character could catch). Most participants switched to using a similarity-based strategy and produced more accurate judgments. The second study then exposed 60 participants to a linear task whose solution was not conducive to similarity-based strategies but rather rule- based strategies. Those participants who employed a similarity-based strategy made poorer judgments. The experiments were conducted with financial support from the Swiss National Science Foundation.
Moving Forward
Cognitive load does not per se lead to worse performance, but rather it can, dependent on strategy choice, lead to better performance. The researchers believe that it is important to decipher cognitive strategies that people choose under given levels of cognitive load. Hoffmann claims, “A better understanding of these cognitive strategies may permit future studies to predict the precise circumstances under which people can solve a problem particularly well.”
A region of the brain known to play a key role in visual and spatial processing has a parallel function: sorting visual information into categories, according to a new study by researchers at the University of Chicago.
Primates are known to have a remarkable ability to place visual stimuli into familiar and meaningful categories, such as fruit or vegetables. They can also direct their spatial attention to different locations in a scene and make spatially-targeted movements, such as reaching.
The study, published in the March issue of Neuron, shows that these very different types of information can be simultaneously encoded within the posterior parietal cortex. The research brings scientists a step closer to understanding how the brain interprets visual stimuli and solves complex tasks.
“We found that multiple functions can be mapped onto a particular region of the brain and even onto individual brain cells in that region,” said study author David Freedman, PhD, assistant professor of neurobiology at the University of Chicago. “These functions overlap. This particular brain area, even its individual neurons, can independently encode both spatial and cognitive signals.”
Freedman studies the effects of learning on the brain and how information is stored in short-term memory, with a focus on the areas that process visual stimuli. To examine this phenomenon, he has taught monkeys to play a simple video game in which they learn to assign moving visual patterns into categories.
“The task is a bit like a baseball umpire calling balls and strikes,” he said, “since the monkeys have to sort the various motion patterns into two groups, or categories.”
The monkeys master the tasks over a few weeks of training. Once they do, the researchers record electrical signals from parietal lobe neurons while the subjects perform the categorization task. By measuring electrical activity patterns of these neurons, the researchers can decode the information conveyed by the neurons’ activity.
“The activity patterns in these parietal neurons carry strong information about the category that each motion pattern gets assigned to during the task,” Freedman said.
(Image: Thinkstock)