Cognitive Daily reports nearly every day on fascinating peer-reviewed developments in cognition from the most respected scientists in the field.
Greta Munger is Associate Professor of Psychology at Davidson College whose works include The History of Psychology: Fundamental Questions. Dave Munger is a writer whose works include Researching Online and The Pocket Reader. And yes, he is married to Greta.
When two athletes are the same size and strength, what makes one better than the other? In many sports, the best athletes are the ones who can react more quickly to game situations than others. Are they just generally better at focusing their attention where it needs to be? Or have they learned some skill set specific to the game at hand?
Attention researchers have made some efforts to learn if athletes perform better in visual tasks than non-athletes, but the results have been mixed. In some experiments, athletes react faster than non-athletes, but in others, there is no discernible difference. For example, when a central arrow points to one of four surrounding boxes, and then an object quickly flashes in one of the squares, athletes are faster than non-athletes to identify the object when it flashes where the arrow was not pointing. But in experiments where different types of cues were used, no difference was found between athletes and non-athletes.
We've reported on studies about cell phones and driving before. A general consensus has formed that driving with cell phones (even hands-free phones) is dangerous. What matters most, it appears, isn't so much the physical aspect -- holding and operating the phone -- but how demanding the conversation itself is.
Research on aging has suggested that older drivers may be even more impaired by driving with a cell phone than younger drivers, since older adults tend to perform worse on "dual task" activities than younger adults. But what about the years of driving experience that older adults have? Can't they compensate for slower reaction time with more careful driving?
David Strayer and Frank Drews had older and younger adults perform the same driving simulator task. Half of them talked on a hands-free cell phone while driving, and the other half didn't. The task was to follow a pace car in the right lane of a three-lane freeway. The pace car was programmed to randomly brake at random intervals along the 24-mile simulated course. Here's a picture of the simulator they used (from the manufacturer's web site):
When human infants are born, the physical structure of their brains has not fully developed: the human brain continues to grow for more than two years after birth. It's very clear that newborn infants don't have the same cognitive abilities as babies even 6 months older. For example, they can't move their heads follow along a movement with their eyes. They appear to have very little control over their limbs. Three-month-olds have difficulty reaching and grasping objects. For humans, walking or crawling isn't a remote possibility for more than six months. Contrast this to wildebeasts, for example, which can run within 15 minutes of birth, or whales, which can swim and follow their mothers virtually as soon as they are born.
So what is it that these animals have that humans don't have? Research with primates has shown that the same region of the brain is activated when they watch another animal performing an action as when they perform the action themselves. So perhaps what babies lack is a recognition of the relationship between their own actions and the results of those actions: they lack goals.
There was a fascinating article in the Washington Post last May about Dilbert creator Scott Adams' battle with focal dystonia. Though the symptoms of this disorder are involuntary muscle contractions (in Adams' case, his right pinky finger), the root of the problem is in the brain. For Adams, it has meant suspending his cartooning career more than once. The first time, he taught himself to draw with his left hand, only to see the symptoms reappear there. He's also tried grueling physical therapy regimens. His most recent effort to battle dystonia has been drawing his cartoons using a computer graphics tablet.
So what's different about brains with focal dystonia? Neuroimaging has found that the basal ganglia is the affected area of the brain -- not surprisingly, this is the area responsible for motor control. People suffering from focal dystonia are also limited in their ability to plan and execute muscle movements. So though the most common form of focal hand dystonia is simply called "writer's cramp," clearly there's much more going on here.
There is little doubt that the cognitive demands of conversation can affect our awareness of the world around us. Everyone has a story of a near-miss collision with some clueless airhead driving who was jabbering away on the cell phone. A co-worker once tearfully told me of the time she was in an argument with her boyfriend while parked in his car at the side of the road. Furious, he got out of the car and slammed the door. He never noticed the passing car that hit him and instantly killed him. Was this a freak accident, or does conversation—and not just cell phone conversation—impair our ability to drive and assess the traffic around us?
Although there is a growing consensus that talking on cell phones—even hands-free phones—is a distraction that impairs driving ability (we've reported on one study by David Strayer and William Johnson confirming this notion), many researchers have suggested that in-person conversation may not have the same effect, because passengers can see the traffic patterns and slow the conversation when a difficult driving situation arises. A group led by Leo Gugerty designed two experiments to try to determine if car passengers adapted their conversation for tough driving situations.
Gugerty's team used a simple driving simulator for their task (you can see it here—it's more sophisticated than what Strayer and Johnson used, but still not exactly a realistic reproduction of real driving). In their first experiment, the team used the same task as Strayer and Johnson: the "passenger" gives the driver a word, then the driver must repeat a new word that begins with the last letter of the original word. But instead of simply navigating a path, drivers had to perform several tasks designed to replicate real driving, like remembering the locations of other vehicles, avoiding crashes, detecting hazards, or remembering when vehicles were in the car's blind spot. In a second version of the task, designed to approximate talking on a hands-free phone, the conversants were placed in adjacent cubicles where they could not see the driving similator. Drivers were also tested with no conversation. To motivate them to try their best, driver-passenger teams were told that the best two teams would receive a $25 reward.
Gugerty et. al did not find a significant difference between driving performance with on-board passengers and remote conversants—in both cases, driving was significantly worse than with no conversation. What's more, passengers did not slow the conversation during hazardous driving situations—in fact, the in-car conversation was faster than the remote conversation.
But perhaps the research participants simply felt that the verbal task was more important than the driving task, and so neglected the driving task. In a second experiment, the research team decided to try giving separate rewards for driving and conversing: each team could earn up to $3.75 for good driving, and up to $3 for good performance on the verbal task. They also made the verbal task more difficult for drivers: the passengers simply read words off a computer screen, and only the drivers had to generate new words. Since passengers never had to think of new words, the drivers would have to respond more frequently. As before, researchers found no difference between in-person and remote conversations: passengers did not slow their conversations to help the driver, even in difficult driving situations.
But with this second, more difficult verbal task, drivers performed even worse: here's a graph comparing the first experiment (easy verbal task) with the second (hard verbal task):
The decrement of the harder verbal task was largest for crash avoidance, cars recalled, and reaction time—hardly insignificant aspects of driving ability.
The authors are careful to point out that their task is by no means an accurate model of real driving, or real conversation. Participants tended to get into a rhythm in the verbal tasks, and this rhythm seemed to guide the pace of talking much more than the driving situation. Perhaps real conversation, especially with real passengers, is more adaptive to driving situations.
On the other hand, as my co-worker's tragic example demonstrates, sometimes conversations can seem more important than the driving situation. It's not difficult to imagine other such conversations: what if a lawyer is negotiating a multi-million-dollar contract on a cell phone? Would she give precedence to that conversation, or the more mundane task of merging onto the interstate? Gugerty et al.'s research is a strong reminder that the substantive demands of conversation are a significant drain on cognitive resources. There are some situations where we may not be able to trust ourselves not to talk, even when our own lives are at stake.
Gugerty, L., Rakauskas, M., & Brooks, J. (2004). Effects of remote and in-person verbal interactions on verbalization rates and attention to dynamic spatial scenes. Accident Analysis and Prevention, 36(6), 1029-43.
Dozens of studies have confirmed both psychological and physical benefits of exercise. The results seem clear enough: a regular program of cardiovascular exercise has been shown not only to promote physical well being, but also to abate depression, decrease anxiety, and improve overall quality of life. But James Annesi noted that most of these studies were implemented the same way: participants agree to a preset program of exercise, carefully controlled and monitored by experimenters. Might the psychological benefits only be an artifact of all the attention they were getting? It's possible, for example, that the positive results might merely have been the result of the Hawthorne effect (which we've discussed here): the simple fact that they were being studied may have improved the participants' sense of well-being.
Annesi designed a study to try to minimize the impact of the experimenter by putting participants in charge of their own exercise programs. He recruited forty-two adults to take part in a simple study. These were people who had already chosen on their own to enroll in a community fitness center, and instead of following a carefully planned routine, the participants were allowed to choose between exercise bikes, treadmills, rowing machines, or elliptical trainers. Further, there was no required regimen—they could exercise as long and frequently as they wanted (or as quickly and infrequently). The only guidance they were given was a one-page sheet indicating that three or more cardiovascular sessions per week of 20 to 30 minutes could improve fitness. The only requirement was that the participants agreed to not do any other type of exercise outside of the fitness center, for a period of twelve weeks.
Annesi measured fitness with a treadmill test and measured indicators of Depression and Tension using the Profile of Mood States, a short questionnaire that gave people words describing emotions and asked them how much they were felt those emotions during the past week. He took the same measurements after the 12 weeks were completed. Here's a summary of the results:
Both Depression and Tension scores were significantly lower, for both men and women—even when their responses initially fell in the "normal" range. There was also a small improvement in cardiovascular fitness (as measured by maximum oxygen intake), but this was not correlated with either of the two measures of mental health. Even though participants averaged under two exercise sessions per week (about 20 sessions on average for the entire 12 weeks), they still achieved significant mental and physical health benefits. Since the influence of the experimenter was minimal compared to other studies, Annesi argues that the benefits of exercise are likely due to the exercise itself, rather than the artifice of the study.
Annesi, J.J. (2003). Sex differences in relations of cardiorespiratory and mood changes associated with self-selected amounts of cardiovascular exercise. Psychological Reports, 93, 1339-1346.
My favorite bike shop has a photo of bicyclists lighting up cigarettes for each other as they rode along during a 1920s stage of the Tour de France. After getting over our astonishment that they can actually manage to light cigarettes without even getting off their bikes, we look at the photo today and think "how could those riders not know what those cigarettes were doing to their lungs?"
Surely today's athletes know that using drugs ranging from nicotine to alcohol to cocaine can seriously impair their ability to perform in competition, don't they? Supporters of scholastic athletics point to evidence that seems to show that athletes get better grades and have lower rates of substance abuse compared to the rest of the school-age population, but the actual results are mixed: while most studies have found lower use of cigarettes, marijuana, and cocaine among adolescent student athletes, they have also found higher use of alcohol, steroids, and smokeless tobacco.
Michele Moore and Chad Werch suspected that some of the reason for the varied study results may be that different sports may be associated with different types of substance use. They surveyed 891 Florida 8th graders, asking them not only what drugs they used (and verifying reports of alcohol use with a saliva test), but also what sports they participated in and whether they competed in interscholastic athletics.
Their first interesting result had little to do with athletics at all: general substance use statistics
Male
Female
Black
White
Other
Alcohol use
18.7%
17.4%
10.1%
22.6%
18.1%
Heavy drinking
5.0%
5.1%
1.7%
7.0%
5.2%
Cigarette use
6.6%
8.4%
2.4%
10.5%
8.6%
Marijuana use
5.8%
4.1%
2.4%
5.7%
6.9%
It was a surprise to me that black 8th graders had a lower incidence of substance use than whites, across the board. Next the researchers analyzed which specific sports were associated with specific substance use. They found different results for different sports, and even different results for same-sport-different-gender athletes. For example, male swimmers were more likely than other males drink heavily, but female swimmers were not. Female skateboarders were more likely than other females to smoke marijuana, but male skateboarders were not.
There were some sports which were associated with lower substance use than among nonparticipants, including basketball, cheerleading, and swimming out of school. However, for sports where a significant correlation was found, in most cases the association was a negative one.
While this study is neither experimental nor longitudinal, and therefore cannot make any solid conclusions about whether sports participation causes substance use or abuse, Moore and Werch do speculate on some of the causes. Skateboarding, as a male-dominated sport, may lead females to be negatively influenced by the males in the group. For males, school-sponsored sports tend to be associated with more substance use, whereas female substance use is associated more often with out-of-school sports. It's possible that the macho ethos of male-dominated sports such as wrestling and football contributes to substance use among male athletes.
Whether or not participation in athletics causes substance use and abuse in middle-schoolers, this study certainly throws a new light on the arguments of those who claim that sports participation helps "build character" or creates "solid citizens." And, like the early athletes in the Tour de France, we can't assume that kids know that these substances may impair their performance in their chosen sports. What they may need is more education about the negative impact of their drug of choice.
Moore, M.J. & Werch, C.E. (2005). Sport and physical activity participation and substance use among adolescents. Journal of Adolescent Health, 36, 486-493.
With my high school reunion coming up, memories just seem to well up out of nowhere. One of the most powerful was that of my cross-country coach's booming voice yelling "stride, Munger, stride!" across the track. I wasn't the best runner on the team, but whenever I heard that voice, I'd always start running faster. Sometimes when I'm out for my morning run, I wish I still had my coach's voice to urge me on.
I've never had any doubt that verbal encouragement helped me perform better on the track, but I have wondered what exactly about the encouragement is helping. Does it just increase my "will" to run faster? Does it literally make me feel better? Or does it just distract me from my struggles?
Studies have confirmed that encouraging words do indeed decrease runners' own ratings of how tired they are. Playing music during exercise has the same effect. A group led by Joseph Andreacci wanted to extend this research to learn what specific factors led to runners feeling less exerted. They devised an experiment, published in the International Journal of Sport Psychology, which measured several additional factors.
Thirty-six volunteers, all college-age women, agreed to participate in the study. They were first tested for the maximum volume of oxygen they could use in a workout by running on a treadmill until they were exhausted. Their noses were clipped shut so a mouthpiece could measure the amount of oxygen consumed. After they were rested, they participated in a baseline test, with no verbal encouragement. During this test, which became gradually more difficult, they not only rated their overall level of exertion, but also gave separate ratings for exertion in breathing and in the legs. Ratings were taken at low, medium, and high levels of exertion (these were defined as 37, 54, and 80 percent of maximum oxygen consumption, to account for different levels of fitness in the participants).
Two weeks later, they returned for a similar test—except this time, the women were given differing levels of verbal encouragement. As expected, verbal encouragement decreased the overall ratings of exertion, but the specific ratings told a different story:
While verbal encouragement significantly lowered exertion ratings for legs, the small difference in chest exertion ratings did not rise to the level of statistical significance. Heart rates as well remained the same for both conditions. There was also no difference between offering encouragement every 20 seconds or every 60 seconds—both were equally successful. The entire difference in overall exertion levels appears to be accounted for by the lowering of perceived leg exertion. Apparently, words of encouragement can impact the legs, but not the lungs.
Andreacci et al. argue that people could feel less exerted when they focus on the external environment, instead of their own internal feelings. The verbal encouragement, even occasional, causes runners to concentrate on the social interaction with the "cheerleader" instead of her own exhaustion. It was certainly true that when my track coach yelled at me, I wasn't thinking about my pain—I was trying to figure out what to do to get him to stop yelling. Maybe it would be better if he didn't show up for my class reunion—I might feel a sudden urge to start running around in circles in my tuxedo!
Andreacci, J., Robertson, R., Goss, F. L., Randall, C. R., Tessmer, K. A., Nagle, E. E., & Gallagher, K. A. (2004). Frequency of verbal encouragement effects sub-maximal extertional perceptions during exercise testing in young adult women. International Journal of Sport Psychology, 35(4), 267-283.
It has been known for some time that cell phones can lead to driving accidents. After watching the behavior of some other drivers on the road, I'm sometimes surprised that there aren't more cell-phone-related accidents than there already are. With well over 100 million cell phone users in the U.S. alone, the problem isn't going to get any smaller.
Until recently, there has been some dispute about exactly why cell phones are unsafe for drivers. Two high-profile studies in the 1990s suggested that any manual manipulation of devices in a car, including not only dialing a cell phone, but also adjusting the radio and other gadgets, led to poor driving. This has led to the rise of hands-free phones, voice-activated phones, and been accompanied by even more gadgets, including GPS, DVD players, and even video games in cars.
In 2001, however, David Strayer and William Johnson of The University of Utah conducted a study which helped narrow down precisely where the danger in cell phone use lies ("Driven to Distraction: Dual-Task Studies of Simulated Driving and Conversing on a Cellular Telephone," Psychological Science, 2001).
In their first experiment, Strayer and Johnson had volunteers perform a simple simulated driving task: using a joystick to make a cursor to follow a dot moving randomly back and forth across the screen (though this reminds me of the primitive "games" I used to type into my Commodore-64 from computer magazines in the early 1980s, it's a reasonable simulation of the cognitive demands of driving a car). At random intervals, the dot would turn either green or red. On a "red light," participants were supposed to press the "brake" button on the joystick. After a practice round with no distractions, participants either had a conversation on a handheld or hands-free cell phone (what did they talk about? The issues of the day while the experiment was being conducted: the Clinton impeachment scandal or the Salt Lake City Olympics bribery scandal). A control group listened to the radio or an audiobook.
Strayer and Johnson found no difference between people who used a handheld or hands-free cell phone, and no difference between radio/audiobook listeners and the driving-only condition. However, the cell-phone talkers missed more than twice as many red lights as the other participants:
In addition to the accuracy problems, cell phone users also showed slower reaction times compared to when they were driving alone.
But does any conversation lead to driving errors? In a second experiment, Strayer and Johnson used a similar apparatus, but instead of using red and green lights, they had participants drive over "easy" and "difficult" courses. The volunteers were first asked to simply repeat words to the experimenter over the telephone. Next they were asked to generate a new word starting with the last letter of the word the experimenter gave them (for example if the experimenter said "salmon," the volunteer could respond "nicotine"). The results were as follows:
Strayer and Johnson used a statistical method to measure the number of errors the drivers made. There wasn't a significant difference in errors on the easy course, but on the difficult course, when drivers had to generate words in response, they made significantly more errors. So the key seems to be not simply that drivers are having a conversation, but that they are actively generating responses. In these conditions, drivers are more likely to make errors. If word of this result gets out to the gadget-makers, perhaps the next must-have phone will have a conversation analyzer that automatically warns you if you're talking safely!
Learning to walk was a passion for my son Jimmy. He would sweat and struggle with it until finally he had it mastered—and then it was off to the races. My daughter Nora, by contrast, didn't seem to mind not being able to walk. After all, if you didn't walk, then some sweet grown-up would soon show up and carry you wherever you wanted to go. The photo below illustrates another way Nora convinced others to do the walking for her:
Nora apparently was oblivious to the fact that parents, grandparents, aunts, and uncles around the world watch infants' progress in walking with anxious anticipation—all the while dreading the thought that little Johnny might not learn to walk as quickly as little Joey across the street.
For nearly a century, psychologists have studied infant walking and developed a seemingly infinite variety of explanations about when infants learn to walk. While they've typically agreed that babies will not learn to walk until they have sufficient strength and balance, they've disagreed about what causes these two factors to develop. One hypothesis holds that it is the physical maturation of the body that enables walking: once legs are long enough and the chubby baby fat yields to muscle, then walking naturally follows. Another explanation suggests that the key is the development of the brain. The brain increases from 30% to 70% of its adult size by age 2. Perhaps it's this phenomenal growth of brain power that allows kids to manage to balance themselves for those critical first few steps. A third possibility is that learning to walk simply takes practice, and the more practice a baby has, the sooner she will be able to walk proficiently.
Karen Adolph and Patrick Shrout of New York University and Beatrix Vereijken of the Norwegian University of Science and Technology designed a study to try to determine which of these theories is most promising ("What Changes in Infant Walking and Why," Child Development, 2003). They developed a simple method to record the footsteps of hundreds of infants, as well as a few kindergartners and adults to compare them to. The method was decidedly low tech: they attached moleskin pads to the walkers' shoes (a triangle at the toe and a square at the heel), then inked them up with different colors for each foot and had them walk the length of a sheet of butcher paper. The marks provided a permanent record of each walker's path.
(As a demonstration of the difficulty of conducting experiments with infants, the researchers had to use a few tricks to get them to complete the task. The babies walked across the top of a long platform, raised about 3 and a half feet, so that there was no possibility of their running away. For safety, the experimenter walked alongside the infants, who were called by their parents at the end of the platform. What's more, the data for 11 infants had to be scrapped because they refused to hold still to have their bodies measured.)
The researchers carefully tracked age and the start of walking for each of the infants, and measured the leg length, weight, and Ponderal Index (a measure of "chubbiness") for all participants. The youngest babies took the shortest steps and had the largest step width. As they became better walkers, their steps became narrower and longer compared to their leg length. There were no significant differences in walking ability between kindergartners and adults.
Adolph et al. then cross correlated the data they had compiled with all the different developmental factors they had measured. None of the physical measures—Ponderal Index, leg length, weight, and so on, made a significant contribution to the variability in infant walking ability. Even the age of the infant was not a significant factor. The only significant contributor to walking ability was days of practice, which was determined simply by the number of days since the child was first able to walk.
The researchers reasoned that physical maturity or brain development could not be responsible for the ability to walk. The fact that walking begins at a wide variety of ages means that it is probably not related to the development of the brain: babies' brains simply don't mature much differently from one another. Once a baby decides to try to start walking, he or she progresses just about as rapidly as any other child, based on how much the baby practices.
This model certainly explains the difference between Jimmy and Nora's learning to walk. Nora simply cared less about walking, and so chose to learn how to do it later than her brother. Once she decided to do it, she learned to walk as well as anyone. Jimmy was an early walker, but he didn't learn how to do it any faster or slower than anyone else.
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Cognitive Daily reports nearly every day on fascinating peer-reviewed developments in cognition from the most respected scientists in the field.
