"Quiet Eye" Can Help A Surgeon's Patients And Golf Game

Surgeons now have a really good excuse to be out on the golf course.  Researchers have shown that the same training technique that will improve their putting can also improve their operating skills.  Dr Samuel Vine and Dr Mark Wilson, from Sport and Health Sciences at the University of Exeter, tested both elite golfers and surgical residents in two separate experiments using the gaze control technique known as the “Quiet Eye.”


First, they divided 22 elite golfers, (handicaps less than 6), into two groups after their baseline putting performance was measured.  The control group received no additional training while the experimental group participated in Quiet Eye (QE) training, a method first developed by Dr. Joan Vickers of the University of Calgary.  They were instructed to follow these steps:

1. Assume your stance and align the club so your gaze is on the back of the ball.
2. After setting up over the ball, fix your gaze on the hole. Fixations toward the hole should be made no more than 3 times.
3. The final fixation should be a QE on the back of the ball. The onset of the QE should occur before the stroke begins and last for 2 to 3 seconds.
4. No gaze should be directed to the clubhead during the backswing or foreswing.
5. The QE should remain on the green for 200 to 300 ms after the club contacts the ball.

While several earlier studies have shown the effectiveness of using QE in lab-based putting experiments, Vine and Wilson wanted to add two additional tests.  Would the golfers not only putt better in the lab, but also retain that performance under induced stress and in real world, golf course conditions?

The stress was added by telling the golfers that they were playing for a $50 prize as well as having their final scores posted at their home golf courses.  Even though the two groups showed no difference at the pre-training baseline testing, the QE group had significantly better putting scores than the control group in all three scenarios, including a decrease of two putts per round.

So, QE will help a surgeon on the green but what about in the operating room?  Knowing the positive results that athletes have seen, Vine and Wilson wondered if gaze control could help other professions, especially medicine.  Working in collaboration with the University of Hong Kong, the Royal Devon and Exeter NHS Foundation Trust and the Horizon training centre Torbay, the University of Exeter team brought thirty medical students together to find out....
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Aaron Rodgers, Working Memory and 10,000 Hours Of Practice

Assuming the Packers’ quarterback does not have super-human vision or a time machine, these comments must refer to his ability to recognize opposing defensive formations, adjust quickly to their movements and pick out an open receiver.  It is a skill that all young players would like to have and their coaches would like to teach.
Of course, the ongoing debate in the sports world is if great perceptual awareness and quick decision making are gifts you’re born with or ones you can develop with practice.  The extreme ends of that continuum seem illogical, that a player can excel with no practice or that anyone who practices enough can be a superstar.  Instead, the discussion has turned to the gray area in between looking for the right combination and the direction of causation between the two.
At the center of the debate for the last 20 years, Florida State psychology professor K. Anders Ericsson has held to a theory that enough deliberate practice, described as a focused activity meant to improve a specific skill, can make up for or even circumvent the lack of general, innate abilities.  His research has shown that about 10,000 hours of practice is the minimum required to rise to an expert level of most knowledge domains, including sports.
Now, in a new study published in Current Directions of Psychological Science, psychologists David Z. Hambrick of Michigan State University and Elizabeth J. Meinz of Southern Illinois University Edwardsville examined this interplay between basic abilities, like working memory capacity, and acquired knowledge learned through practice.  “We have been especially interested in the question of whether various forms of domain knowledge moderate the impact of basic cognitive abilities on performance,” the authors wrote.
Working memory is used in complex tasks that require holding information in the mind while also trying to reason or comprehend the environment.  Think of Rodgers remembering the pass routes of all of his receivers while processing the movements of eleven defenders around him.
Hambrick and Meinz wanted to find out if the working memory of domain experts, like Rodgers, has as much as an impact on their performance as their years of deliberate practice and learned knowledge of their specialized world.  Previous research has shown that a person’s working memory capacity is strongly correlated with abstract reasoning, problem solving, decision making, language comprehension, and complex learning.

After a great Aaron Rodgers performance, you will usually hear at least one of two phrases uttered by post-game football analysts, “he has a great ability to see the field,” or “the game has really slowed down for him.”

Back in 2002, Professor Hambrick tested this relationship using a baseball domain.  Participants were first tested on their overall baseball acumen and then completed a complex-scan task to test their working memory capacity.  Complex-scan tests combine information storing with information processing.  An example would be reading a series of sentences aloud while also remembering the last word of each sentence.

After the baseline tests, the volunteers listened to radio broadcasts of baseball games and were asked to remember the major events of the game and specific information about the players.  As expected, those who had a higher baseball IQ did better on the recall test.  However, working memory capacity also had a strong correlation with success. As Hambrick concluded, “Working-memory capacity was as important as a predictor of memory performance at high levels of domain knowledge as it was at low levels.”

In the current study, the domain shifted to piano playing while the results were similar.  Fifty-seven pianists with a wide range of lifetime deliberate practice hours, from 260 to over 31,000, were first given a complex-scan test to measure their working memory limits.  Then, they were given a musical piece that they had never seen before and asked to play it with no practice, called sight-reading.

As the authors reported, “Not surprisingly, we found that deliberate practice was a powerful predictor of sight-reading performance. In fact, it accounted for nearly 50% of the variance. However, we also found that working-memory capacity was a positive predictor of performance above and beyond deliberate practice.”

So, at least in the case of working memory, an ingrained ability does have some importance alongside the hours of practice.  Moreover, deliberate practice that also increases your working memory capacity should yield even better results.  Focused training on improving both the storage and processing of information seems to be the key to better performance.

Of course, for most football analysts, saying a quarterback can now “see the field better” is a little easier than saying “activation of domain knowledge by the familiar context did not reduce the effect of working memory capacity on performance.”

Little Old Ladies May Want Athletes To Help Them Cross The Road

Photo credit: Beckman Institute CAVE

Boy Scouts just got some competition.  Now, when little, old ladies need to cross a busy street, they should find a well-trained athlete to do the job, according to University of Illinois researchers. 


In a test of skill transfer, Laura Chaddock, a researcher at the Beckman Institute’s Human Perception and Performance lab, and her team pushed a bunch of college students out into busy traffic to see how well they could navigate the oncoming cars... well, sort of. 

With the help of a virtual 3D environment called the CAVE, volunteer pedestrians can step into a simulated city street scene, seeing traffic whiz by on three surrounding screens, while walking on a synchronized treadmill.  Failure here does not end up in a trip the hospital, just a system reset.


Of the 36 college student participants, half were student-athletes at Illinois, an NCAA Division 1 school, representing a wide variety of sports, including cross-country running, baseball, swimming, tennis, wrestling, soccer and gymnastics. The other half were just regular students matched for similar age, GPA and video game prowess.  

Chaddock hypothesized that the athletes would have the edge in street crossing given their training in busy, attention-demanding sport environments.  Previous studies have found that athletes outperform non-athletes on sport-specific tests of attention, memory, and speed.  


“We predicted that an elite soccer player, for example, not only shows an ability to multitask and process incoming information quickly on a fast-paced soccer field by running, kicking, attending to the clock, noting the present offensive and defensive formations, executing a play, and finding open players to whom to pass” Chaddock wrote.  “He or she also shows these skills in the context of common real world tasks.”


When the students stepped into the CAVE, they encountered a busy city street with cars and trucks zooming by at 40-50 mph.  They were asked to cross the street when they thought it was safe, but could only walk briskly with no sprinting.  To make it more interesting, (and realistic), the students were also given an iPod to listen to music, then a cell phone with an incoming call to distract their attention even more.


The team was correct in its prediction as the athletes completed more successful crossings than non-athletes by a significant margin.  But it wasn’t because the athletes were faster (they were limited to walking) or because they displayed better agility or moves.  Maybe it was because their advanced “field vision” was able to scan the environment for patterns and opportunities to cross better than the untrained eyes of the other students.


“While efficiency of information processing may be one cognitive mechanism underlying athlete and non-athlete differences in street crossing performance,” Chaddock noted,  “additional research is needed to characterize other cognitive factors that play a role in the cognitively complex multitask paradigm that involves attention, speed, working memory and inhibition.”

One other finding of the study confirmed what is probably already obvious.  Students who were talking on the phone when crossing the street were much more likely to not make it to the other side.


You might also like: How To See A 130 MPH Tennis Serve and Breaking Curveballs And Rising Fastballs Are Optical Illusions

Breaking Curveballs And Rising Fastballs Are Optical Illusions

(Credit: iStockphoto/Barry Howell)

Curveballs curve and fastballs go really fast, but new research suggests that no pitcher can make a curveball "break" or a fastball "rise."  Led by Arthur Shapiro of American University and Zhong-Lin Lu of the University of Southern California, the researchers explain the illusion of the curveball's break in a publicly available study in the journal PLoS ONE.

The study comes a year after the same group won the prize for best illusion at the Vision Sciences annual meeting with a demonstration of how an object falling in a straight line can seem to change direction.  That demonstration led to debates among baseball fans over the existence of the break in curveballs, breaking balls and sliders.

There is no debate in the researchers' minds.

"The curveball does curve, but the curve has been measured and shown to be gradual," Shapiro said. "It's always going to follow a parabolic path. But from a hitter's point of view, an approaching ball can appear to break, drop or do a whole range of unusual behaviors."

A little terminology: to many batters and pitchers, a break is a deviation from the relatively straight path of a fastball. In that sense, all curveballs break.  The authors of the study use the term to describe an apparent sudden drop or other change in trajectory as the ball nears home plate. That, they say, is an illusion.

The PLoS ONE study explains the illusion and relates the perceived size of the break to the shifting of the batter's eye between central and peripheral vision.

"If the batter takes his eye off the ball by 10 degrees, the size of the break is about one foot," Lu said.
He explained that batters tend to switch from central to peripheral vision when the ball is about 20 feet away, or two-thirds of the way to home plate. The eye's peripheral vision lacks the ability to separate the motions of the spinning ball, Lu said. In particular, it gets confused by the combination of the ball's velocity and spin.

The result is a gap between the ball's trajectory and the path as perceived by the batter. The gap is small when the batter switches to peripheral vision, but gets larger as the ball travels the last 20 feet to home plate.

As the ball arrives at the plate, the batter switches back to central vision and sees it in a different spot than expected. That perception of an abrupt change is the "break" in the curveball that frustrates batters.

"Depending on how much and when the batter's eyes shift while tracking the ball, you can actually get a sizable break," Lu said. "The difference between central and peripheral vision is key to understanding the break of the curveball."

A similar illusion explains the "rising fastball," Lu added.  The obvious remedy for a batter, repeated by parents and coaches everywhere, is to "keep your eye on the ball."  That is easier said than done, according to the authors. As the ball nears home plate, its size in the batter's field of view spills out of the eye's central vision.

"Our central vision is very small," Shapiro said. "It's the size of the tip of your thumb at arm's length. When an object falls outside of that region, strange perceptions can occur."

Lu noted that the spin of the ball tends to draw the eye to the side, making it even harder for the batter to keep the ball in central vision.  "People's eyes have a natural tendency to follow motion," Lu explained.  His advice to hitters: "Don't trust your eyes. Know the limitations of your visual system. This is something that can be trained, probably."

Lu, Shapiro and their co-authors plan to build a physical device to test the curveball illusion. Their study was carried out with volunteers tracking the movement of a disk on a computer monitor.
To the authors' knowledge, the PLoS ONE study represents the first attempt to explain the break in the curveball purely as a visual illusion. Others have tried to explain the break as a result of the hitter overestimating the speed of a pitch.

Responding to comments from baseball fans, Lu agreed that on television, pitches filmed from behind home plate appear to break. He called it a "geometric illusion" based on the fact that for the first part of a pitch, the viewer sees little or no vertical drop.

The ball is falling at the same rate throughout the pitch, Lu said, but because the pitcher tosses the ball at a slight upward angle, the first part of the pitch appears more or less flat.  As a result, the drop of the ball near home plate surprises the eye.  For Shapiro and Lu, who have studied visual perception for many years, the PLoS ONE results go beyond baseball.

"Humans constantly shift objects between central and peripheral vision and may encounter effects like the curveball's break regularly," the authors wrote. "Peripheral vision's inability to separate different visual signals may have f ar-reaching implications in understanding human visual perception and functional vision in daily life."

Source: University of Southern California and Arthur Shapiro, Zhong-Lin Lu, Chang-Bing Huang, Emily Knight, Robert Ennis. Transitions between Central and Peripheral Vision Create Spatial/Temporal Distortions: A Hypothesis Concerning the Perceived Break of the Curveball. PLoS ONE, 2010; DOI: 10.1371/journal.pone.0013296

See also: Morning Type Pitchers Do Better In Day Games and Virtual Reality Lab Proves How Fly Balls Are Caught

New Video Games Help Blind Kids Play

VI Fit, a project at the University of Nevada, Reno, helps children who are blind become more physically active and healthy through video games. The human-computer interaction research team in the computer science and engineering department has developed a motion-sensing-based tennis and bowling exergame.

"Lack of vision forms a significant barrier to participation in physical activity and consequently children with visual impairments have much higher obesity rates and obesity-related illnesses such as diabetes," Eelke Folmer, research team leader and assistant professor in the computer science and engineering department, said.

"Exergames" are a new type of video game that use physical activity as input and are considered powerful weapons in the fight against obesity. Unfortunately, exergames have not yet been accessible to children with visual impairments, although it is evident they could benefit from them the most.
"Our games are adaptations of the popular Nintendo Wii Sports exercise games that have been modified so they can be played without visual feedback," Folmer said.

VI Tennis and VI Bowling are the first of several games to be made available. VI Tennis implements the gameplay of Wii sports tennis providing audio and vibrotactile cues that indicate when to serve and when to return the ball. It can be played against the computer or against a friend using two Wii remotes.

"VI Tennis was evaluated at Camp Abilities in New York with 13 children who were blind," Folmer said. "We found our game to engage children into levels of active energy expenditure that were high enough to be considered healthy, which shows the feasibility of using video games as a health-intervention method."

The gameplay of Wii sports bowling is implemented through VI Bowling with a novel motor-learning feature that allows players to find the direction in which to throw their ball using vibrotactile feedback. Audio and speech effects are used to indicate the result of each throw. VI Bowling was evaluated with six adults and was found to yield levels of active energy expenditure that are comparable to walking.

Compared to the general population, individuals with visual impairments have even fewer opportunities to engage in physical activities that provide the amounts and kinds of stimulation needed to maintain adequate fitness and support a healthy standard of living. Folmer and his team are exploring alternative forms of interaction that allow individuals with visual impairments to play exercise games and to increase their participation in physical activity.

To play the VI Fit games, a user would need a Wii remote and a Windows PC with bluetooth support or a USB bluetooth dongle. The games can be downloaded using instructions at www.vifit.org. The games are not affiliated with or endorsed by Nintendo.

Source:  University of Nevada, Reno

See also: How To See A 130 MPH Tennis Serve and Video Games Move From The Family Room To The Locker Room

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Top Athletes Can React Quicker

A study conducted by scientists at Brunel University and at the University of Hong Kong has found that expert sportsmen are quicker to observe and react to their opponents' moves than novice players, exhibiting enhanced activation of the cortical regions of the brain.

The results of the study, which appear in the most recent issue of NeuroReport, show that more experienced sports players are better able to detect early anticipatory clues from opposing players' body movements, giving them a split second advantage in preparing an appropriate response.
 
Recent studies have demonstrated how expertise affects a range of perceptual-motor skills, from the imitation of hand actions in guitarists, to the learning of action sequences in pianists and dancers. In these studies, experts showed increased activation in the cortical networks of the brain compared with novices.

Fast ball sports are particularly dependent on time-critical predictions of the actions of other players and of the consequences of those actions, and for several decades, sports scientists have sought to understand how expertise in these sports is developed.

This most recent study, headed by Dr Michael Wright, was carried out by observing the reaction time and brain activity of badminton players of varying degrees of ability, from recreational players to international competitors. Participants were shown video clips of an opposing badminton player striking a shuttlecock and asked to predict where the shot would land.

In all participants, activation was observed in areas of the brain previously associated with the observation, understanding and preparation of human action; expert players showed enhanced brain activity in these regions and responded more quickly to the movements of their opponents.

Expertise in sports is not only dependent on physical prowess, then, but also on enhanced brain activity in these key areas of the brain. The observations made during this study will certainly have implications for how we perceive the nature of expertise in sport and perhaps even change the way athletes train.

See also: The Cognitive Benefits of Being a Sports Fan and How To See A 130 MPH Tennis Serve

Source:  Wolters Kluwer Health / Lippincott Williams & Wilkins and Functional MRI reveals expert-novice differences during sport-related anticipation : Neuroreport

Soccer Referees Biased Against Tall Players

In this World Cup year, when football (soccer) passions are running high, supporters might be forgiven for objecting to every decision to award a foul against their team, made by referees. But they might also have a point. Researchers at Rotterdam School of Management, Erasmus University have researched all recorded fouls in three major football competitions over seven years. They discovered an ambiguous foul is more likely to be attributed to the taller of two players.

Dr. Niels van Quaquebeke and Dr. Steffen Giessner, scientists at Rotterdam School of Management, Erasmus University began their research by transferring their insights from decision making in business into the arena of sports. Specifically, they wanted to investigate whether people consider the available information in such ambiguous foul situations in an unbiased, i.e. subconsciously unprejudiced, way.

Based on evolutionary and linguistic research which has revealed that people associate the size of others with concepts such as aggression and dominance, Van Quaquebeke and Giessner speculated that ambiguous fouls are more likely to be attributed to the taller of two involved players. Results indicate that respectively taller people are more likely to be perceived by referees (and fans!) as foul perpetrators and their respectively smaller opponents as foul victims.

To put their assumption to a test, the scientists analysed all fouls recorded by Impire AG in seven seasons of UEFA Champions League (32,142 fouls) and German Bundesliga (85,262 fouls), the last three FIFA World Cups (6,440 fouls) as well as data from two additional perceptual experiments with football fans. For all seasons, leagues, and data collection methods, their analyses revealed the same picture confirming their initial assumption: taller people are indeed more often held accountable for fouls than shorter ones -- even when no actual foul was committed.

An article based on their research will be published in the Journal of Sport & Exercise Psychology in February 2010.

Van Quaquebeke said, "We chose football as the context of our studies because the sport often yields ambiguous foul situations in which it is difficult to determine the perpetrator. In such situations, people must rely on their 'instincts' to make a call, which should increase the use and thus the detectability of a player's height as an additional decision cue. Furthermore, the use of referee assistance technology and adequate referee training is frequently debated in association football. Thus, by providing scientific insights on potential biases in refereeing, our work might help officials weigh the options."

Both researchers say, however, that it is not their call how to derive conclusions for football practice.

Sources:   Erasmus University Rotterdam and "How embodied cognitions affect judgments: Height-related attribution bias in football foul calls"

Virtual Reality Lab Proves How Fly Balls Are Caught

While baseball fans still rank "The Catch" by Willie Mays in the 1954 World Series as one of the greatest baseball moments of all times, scientists see the feat as more of a puzzle: How does an outfielder get to the right place at the right time to catch a fly ball?


Thousands of fans (and hundreds of thousands of YouTube viewers) saw Mays turn his back on a fly ball, race to the center field fence and catch the ball over his shoulder, seemingly a precise prediction of a fly ball's path that led his team to victory. According to a recent article in the Journal of Vision ("Catching Flyballs in Virtual Reality: A Critical Test of the Outfielder Problem"), the "outfielder problem" represents the definitive question of visual-motor control. How does the brain use visual information to guide action?

To test three theories that might explain an outfielder's ability to catch a fly ball, researcher Philip Fink, PhD, from Massey University in New Zealand and Patrick Foo, PhD, from the University of North Carolina at Ashville programmed Brown University's virtual reality lab, the VENLab, to produce realistic balls and simulate catches. The team then lobbed virtual fly balls to a dozen experienced ball players.

"The three existing theories all predict the same thing: successful catches with very similar behavior," said Brown researcher William Warren, PhD. "We realized that we could pull them apart by using virtual reality to create physically impossible fly ball trajectories."

Warren said their results support the idea that the ball players do not necessarily predict a ball's landing point based on the first part of its flight, a theory described as trajectory prediction. "Rather than predicting the landing point, the fielder might continuously track the visual motion of the ball, letting it lead him to the right place at the right time," Warren said.

Because the researchers were able to use the virtual reality lab to perturb the balls' vertical motion in ways that would not happen in reality, they were able to isolate different characteristics of each theory. The subjects tended to adjust their forward-backward movements depending on the perceived elevation angle of the incoming ball, and separately move from side to side to keep the ball at a constant bearing, consistent with the theory of optical acceleration cancellation (OAC). The third theory, linear optical trajectory (LOT), predicted that the outfielder will run in a direction that makes the visual image of the ball appear to travel in a straight line, adjusting both forward-backward and side-to-side movements together.

Fink said these results focus on the visual information a ball player receives, and that future studies could bring in other variables, such as the effect of the batter's movements or sound.
"As a first step we chose to concentrate on what seemed likely to be the most important factor," Fink said. "Fielders might also use information such as the batter's swing or the sound of the bat hitting the ball to help guide their movements."

Sources:  Catching fly balls in virtual reality: A critical test of the outfielder problem and Association for Research in Vision and Ophthalmology

How Nerves Affect Soccer Penalty Kicks

Research by the University of Exeter shows for the first time the effect of anxiety on a soccer player's eye movements while taking a penalty.

The study shows that when penalty takers are anxious they are more likely to look at and focus on the centrally positioned goalkeeper. Due to the tight coordination between gaze control and motor control, shots also tend to centralise, making them easier to save. The research is now published in the December 2009 edition of the Journal of Sport and Exercise Psychology.

The researchers attribute this change in eye movements and focus to anxiety. Author Greg Wood, a PhD student in the University of Exeter’s School of Sport and Health Sciences said: “During a highly stressful situation, we are more likely to be distracted by any threatening stimuli and focus on them, rather than the task in hand. Therefore, in a stressful penalty shootout, a footballer’s attention is likely to be directed towards the goalkeeper as opposed to the optimal scoring zones (just inside the post). This disrupts the aiming of the shot and increases the likelihood of subsequently hitting the shot towards the goalkeeper, making it easier to save.”

For their study, the researchers focused on 14 members of the University of Exeter football team. They asked the players to perform two series of penalty shots. First, they were simply asked to do their best to score. The researchers made the second series more stressful and more akin to a penalty shoot-out. The players were told that the results would be recorded and shared with the other players and there would be a £50 prize for the best penalty taker.

The players wore special glasses which enabled the researchers to record precise eye movements and analyse the focus of each footballer’s gaze and the amount of time spent looking at different locations in the goal.

The results showed that when anxious, the footballers looked at the goalkeeper significantly earlier and for longer. This change in eye behaviour made players more likely to shoot towards the centre of the goal, making it easier for the keeper to save. The researchers believe that by being made aware of the impact of anxiety on eye movements, and the affect this has on the accuracy of a player’s shot, coaches could address this through training.

Greg Wood continues: “Research shows that the optimum strategy for penalty takers to use is to pick a spot and shoot to it, ignoring the goalkeeper in the process. Training this strategy is likely to build on the tight coordination between eye movements and subsequent actions, making for more accurate shooting. The idea that you cannot recreate the anxiety a penalty taker feels during a shootout is no excuse for not practicing. Do you think other elite performers don’t practice basic aiming shots in darts, snooker or golf for the same reasons? These skills need to be ingrained so they are robust under pressure”.

Source: University of Exeter: Anxiety, Attentional Control, and Performance Impairment in Penalty Kicks.

How To See A 130 MPH Tennis Serve

For most of us mere mortals, if an object was coming at us at 120-150 mph, we would be lucky to just get out of the way. Players in this week's U.S. Open tennis tournament not only see the ball coming at them with such speed, but plan where they want to place their return shot and swing their racquet in time to make contact. At 125 mph from 78 feet away, that gives them a little less than a half second to accomplish the task.

How do they do it? Well, they're better than you and I, for one. But science has some more specific answers to offer.

Swiss researchers have concluded that expert tennis players, like their own Roger Federer, have an advantage in certain visual perception skills, while UK scientists have shown how trained animals — and presumably humans — can rely on a superior internal model of motion to predict the path of a fast moving object.

For any sport that involves a moving object, athletes must learn the three levels of response for interceptive timing tasks. 

• First, there is a basic reaction, also known as optometric reaction (in other words, see it and get out of the way).

• Next, there is a perceptual reaction, meaning you actually can identify the object coming at you and can put it in some context (for example: That is a tennis ball coming at you and not a bird swooping out of the sky).

• Finally, there is a cognitive reaction, meaning you know what is coming at you and you have a plan of what to do with it (return the ball with top-spin down the right line).

This cognitive skill is usually sport-specific and learned over years of tactical training. Obviously, professional tennis players are at the expert cognitive stage and have a plan for most shots.

But, in order to reach that cognitive stage, they first need to have excellent optometric and perceptual skills.

Leila Overney and her team at the Brain Mind Institute of Ecole Polytechnique Federale de Lausanne (EPFL) studied whether expert tennis players have better visual perception abilities than other athletes and non-tennis players. Typically, motor skill research compares experts to non-experts and tries to deduce what the experts are doing differently to excel.

They carried out seven visual tests, covering a wide range of perceptual functions including motion and temporal processing, object detection and attention, each requiring the participants to push buttons based on their responses to the computer-based tasks and each related to a particular aspect of visual perception.

In this study, which was detailed in the journal PLOS One, Overney wanted to see if the perceptual skills of the tennis players were not only more advanced than non-tennis players but also other athletes of a similar fitness level, (in this case triathletes), to eliminate any benefits of just being in top physical shape.  To eliminate the cognitive knowledge difference between the groups, she used seven non-sport specific visual tests which measured different forms of perception including motion and temporal processing, object detection and attention. The participants watched the objects on computer screens and pushed buttons per the specific test instructions.

The tennis players showed significant advantages in the speed discrimination and motion detection tests, while they were no better in the other categories.

"Our results suggest that speed processing and temporal processing is often faster and more accurate in tennis players," Overney writes. They even scored better then their peers, the triathletes. "This is precisely why we added the group of triathletes as controls because they train as hard as tennis players but have lower visual processing demands in their sport."

Still, are the tennis players really just relying on their visual advantage when given that half second to react? Have their years of practice created an internal cognitive model that anticipates and predicts the path of an object?

Nadia Cerminara worked on that question. Cerminara, of the University of Bristol (UK), designed an experiment that taught household cats to reach with their paw at a moving target. If they successfully touched the target, they received a food reward.

After training the cats to be successful, she recorded their neuronal activity in their lateral cerebellum. Then, she measured the activity again but would block the vision of the cats for 200-300 milliseconds while performing the task. Despite the lapse in visual information, the neuron firing activity remained the same as before. Cerminara concluded that an internal model had been used to bridge the gap and provide a prediction of where the object was headed.

The study was published in the Journal of Physiology.

So, when faced with a blistering serve, science suggests that players like Federer not only rely on their superior perceptual skills, but also have created an even faster internal simulation of a ball's flight that can help position them for a winning return.

Of course, you may want to avoid the world's fastest server, Andy Roddick, especially when he's upset from a bad line call (see video). :-)

Catching Fly Balls Is A Lot Like Rocket Science

Every Little League outfielder knows the feeling.

With the crack of the bat, you see the ball jump into the air. You take a few quick steps forward. Then, as you watch the ball continue to rise faster, you feel your stomach sink knowing that this one is going over your head. What went wrong?

How our eyes, brains, arms and legs combine to track and catch a fly ball has stumped scientists for more than 40 years.

A new study supports the original theory of it all while offering some practical tips.

By watching fielders shag pop flies, researchers have noticed a few interesting quirks. First, great ballplayers will not sprint to the exact spot on the field where they think the ball will land and then wait for it. Rather, they usually adjust their speed to arrive at the landing spot just as the ball arrives.

In fact, a previous study asked fielders to stand still in the outfield and predict where a fly ball will land. While they did poorly on that test, they then demonstrated that, when allowed to move, they were able to go catch similar fly balls. So, the tracking and prediction mechanism seemed to require movement of the player.

Years ago, physicist Seville Chapman proposed a model to explain how players manage the path of a fly ball so that they arrive to intercept it at just the right time. His theory, called Optical Acceleration Cancellation (OAC), used the acceleration of the ball through the vision field as a guide for player movement.

As a fielder watches the ball rise, he moves either forward or backwards so that the ball moves at a constant speed through his field of vision. If he moves too far forward, the ball will rise faster and may eventually fly over his head. If he takes too many steps back, the ball will appear to rise slower and will drop in front of him.

By managing the ball's position with his movement, a fielder will end up at the right spot at the right time. This explains why the stationary fielders could not predict where the ball would land, as they did not have the benefit of OAC.

If we ask real fielders how they knew where to run to catch a ball, they may not respond with, "Well, I simply adjusted my relative field position to keep the tangent of the vertical optical angle to the ball increasing at a constant rate." So, to test the OAC geometric equations against real life, researchers led by Dinant Kistemaker of the University of Western Ontario, compared the predicted running paths from their mathematical simulation with the real running paths of fielders observed in a previous study.

"We have found that running paths are largely consistent with those observed experimentally," Kistemaker told LiveScience. "Largely, and not completely, because the start of fielders is somewhat strange: They tend to step forward first, irrespective of the fact that they have run either forward or backwards to catch that fly ball."

The research is detailed this month in the journal Human Movement Science.

Will those first few steps forward doom the Little Leaguer to years of fly ball nightmares? Actually, it might be our brain's method of improving its viewpoint.

"For a fielder, making a step is a way of changing the magnitude of the optical acceleration, while preserving its informative value," Kistemaker clarified. "A faster rise of the optical acceleration above the detection threshold may outweigh a possible initial step in the wrong direction. Making an initial step forwards is not only easier than making an initial step backwards, but might also be a better choice."

So, if you're now coaching Little Leaguers, be patient. Their brains may still be learning the math.

Please visit my other sports science articles at LiveScience.com

Rotate It Like Ronaldo?

"Rotate it like Ronaldo" just doesn't have the same ring to it as "Bend it like Beckham", but the curving free kick is still one of the most exciting plays in soccer/football. Starting with Rivelino in the 1970 World Cup and on to the specialists of today, more players know how to do it and understand the basic physics behind it, but very few can perfect it. But, when it does happen, by chance or skill, it is the highlight of the game.



But let's take a look at this from the other side, through the eyes of the goalkeeper. Obviously, its their job to anticipate where the free kick is going and get to the spot before the ball crosses the line. He sets up his wall to, hopefully, narrow the width of the target, but he knows some players are capable of bending the ball around or over the wall towards the near post. If you watch highlights of free kick goals, you often see keepers flat-footed, just watching the ball go into the top corner. Did they guess wrong and then were not able to react? Did they guess right but misjudged the flight trajectory of the ball. How much did the sidespin or "bend" affect their perception of the exact spot where the ball will cross the line? To get an idea of the effect of spin, here's a compilation of Beckham's best free kick goals (there's a 15 second intro, then the highlights) :







Researchers at Queen's University Belfast and the University of the Mediterranean in France tried to figure this out in this paper. They wanted to compare the abilities of expert field players and expert goalkeepers to accurately predict if a free kick would result in an on-target goal or off-target non-goal. First, a bit about why the ball "bends". We can thank what's called the "Magnus Force" named after the 19th-century German physicist Gustav Magnus. As seen in the diagram below, as the ball spins counter clockwise (for a right-footed player using his instep and kicking the ball on the right side), the air pressure on the left side of the ball is lower as the spin is in the same direction as the oncoming air flow. On the right side of the ball, the spin is in the opposite direction of the air flow, building higher pressure. The ball will follow the path of least resistance, or pressure, and "bend" or curve from right to left. The speed of the spin and the velocity of the shot will determine the amount of bend. For a clockwise spin, the ball bends from left to right.







The researchers showed the players three different types of simulated kicks, a kick bent to the right, a kick bent to the left and a kick with no spin at all. They showed the players these simulations with virtual reality headsets and computer controlled "kicks" and "balls" which they could vary in flight with different programming. The balls would disappear from view at distances of 10 and 12.5 meters from the goal. The reasoning is that this cutoff would correspond with the deadline for reaction time to make a save on the ball. In other words, if the keeper does not correctly guess the final trajectory and position of the ball by this point, he most likely will not be able to physically get to the ball and make the save.







The results showed that both the players and the keepers, (all 20 were expert players from elite clubs like AC Milan, Marseille, Bayer Leverkusen, Schalke 04), were able to correctly predict the result of the kicks with no spin added. However, as 600 RPM spin, either clockwise or counter-clockwise, was added to the ball, the players success declined significantly. Interestingly, the keepers did no better, statistically, then the field players. The researchers conclusion was that the players used the "current heading direction" of the ball to predict the final result, rather than factoring the future affect of the acceleration and change in trajectory caused by the spin.



Just as we saw in the Baseball Hitting post, our human perception skill in tracking flying objects, especially those that are spinning and changing direction, are not perfect. If we understand the physics of the spinning ball, we can better guess at its path, but the pitcher or the free kick taker doesn't usually offer this information beforehand!



Craig, C.M., Berton, E., Rao, G., Fernandez, L., Bootsma, R.J. (2006). Judging where a ball will go: the case of curved free kicks in football. Naturwissenschaften, 93(2), 97-101. DOI: 10.1007/s00114-005-0071-0

Watching Sports Is Good For Your Brain

When was the last time you listened to a sporting event on the radio? If given a choice between watching the game on a big screen plasma in HD or turning on the AM radio, most of us would probably choose the visual sensation of television. But, for a moment, think about the active attention you need in order to listen to a radio broadcast and interpret the play-by-play announcer's descriptions. As you hear the words, your "mind's eye" paints the picture of the action so you can imagine the scene and situations. Your knowledge of the game, either from playing it or watching it for years helps you understand the narrative, the terms and the game's "lingo".


Now, imagine that you are listening to a broadcast about a sport you know nothing about. Hearing Bob Uecker or Vin Scully say, "With two out in the ninth, the bases are loaded and the Brewers' RBI leader has two strikes. The infield is in as the pitcher delivers. Its a hard grounder to third that he takes on the short hop and fires a bullet to first for the final out." If you have no baseball-specific knowledge, those sentences are meaningless. 

However, for those of us that have grown up with baseball, that description makes perfect sense and our mind's eye helped us picture the scene. That last sentence about the "hard grounder" and the thrown "bullet" may have even triggered some unconscious physical movements by you as your brain interpreted those action phrases. That sensorimotor reaction is at the base of what is called "embodied cognition". 
 
Sian Beilock, associate professor of psychology and leader of the Human Performance Lab at the University of Chicago, defined the term this way: "In contrast to traditional views of the mind as an abstract information processor, recent work suggests that our representations of objects and events are grounded in action. That is, our knowledge is embodied, in the sense that it consists of sensorimotor information about potential interactions that objects or events may allow." She cites a more complete definition of the concept in Six Views of Embodied Cognition by Margaret Wilson. Another terrific overview of the concept is provided by science writer Drake Bennet of the Boston Globe in his article earlier this year, "Don't Just Stand There, Think".


In a study released yesterday, "Sports Experience Changes the Neural Processing of Action Language", Dr. Beilock's team continued their research into the link between our learned motor skills and our language comprehension about those motor skills. Since embodied cognition connects the body with our cognition, the sports domain provides a logical domain to study it.


Their initial look at this concept was in a 2006 study titled, "Expertise and its embodiment: Examining the impact of sensorimotor skill expertise on the representation of action-related text", where the team designed an experiment to compare the knowledge representation skill of experienced hockey players and novices. Each group first read sentences describing both hockey-related action and common, "every-day" action, (i.e. "the referee saw the hockey helmet on the bench" vs. "the child saw the balloon in the air"). They were then shown pictures of the object mentioned in the sentences and were asked if the picture matched the action in the sentence they read.

Both groups, the athletes and the novices, responded equally in terms of accuracy and response time to the everyday sentences and pictures, but the athletes responded significantly faster to the hockey-specific sentences and pictures. The conclusion is that those with the sensorimotor experience of sport give them an advantage of processing time over those that have not had that same experience.


Now, you may be saying, "Ya' think!?" to this somewhat obvious statement that people who have played hockey will respond faster to sentence/picture relationships about hockey than non-hockey players. Stay with us here for a minute, as the 2006 study set the groundwork for Beilock's team to take the next step with the question, "is there any evidence that the athletes are using different parts of their brain when processing these match or no match decisions?" The link between our physical skill memory and our language comprehension would be at the base of the embodied cognition theory. 

So, in the latest research, the HPL team kept the same basic experimental design, but now wanted to watch the participants' brain activity using fMRI scanning. This time, there were three groups, hockey players, avid fans of hockey and novices who had no playing or viewing experience with hockey at all. First, all groups passively listened to sentences about hockey actions and also sentences about everyday actions while being monitored by fMRI.  Second, outside of the fMRI scanner, they again listened to hockey-related and everyday-related action sentences and then were shown pictures of hockey or every day action and asked if there was a match or mis-match between the sentence and the picture.


This comprehension test showed similar results as in 2006, but now the team could try to match the relative skill in comprehension to the neural activity shown in the fMRI scans when listening. Both the players and the fans showed increased activity in the left dorsal premotor cortex, a region thought to support the selection of well-learned action plans and procedures. 

You might be surprised that the fans' brains showed activity in the same regions as the athletes. We saw this effect in a previous post, "Does Practice Make Perfect", where those that practiced a new dance routine and those that only watched it showed similar brain area activity. On the other side, the total novices showed activity in the bilateral primary sensory-motor cortex, an area typically known for carrying out step by step instructions for new or novel tasks. 

So, the interesting finding here is that those with experience, either playing or watching, are actually calling on additional neural networks in their brains to help their normal language comprehension abilities. In other words, the memories of learned actions are linked and assist other cognitive tasks. That sounds pretty much like the definition of embodied cognition and Dr. Beilock's research has helped that theory take another step forward. In her words, "Experience playing and watching sports has enduring effects on language understanding by changing the neural networks that support comprehension to incorporate areas active in performing sports skills."


Take pride in your own brain the next time you hear, "Kobe dribbles the ball to the top of the key, crosses over, drives the lane, and finger rolls over Duncan for two." If you can picture that play in your mind, your left dorsal premotor cortex just kicked into gear!









S. L. Beilock, I. M. Lyons, A. Mattarella-Micke, H. C. Nusbaum, S. L. Small (2008). Sports experience changes the neural processing of action language Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0803424105


Lauren E. Holt, Sian L. Beilock (2006). Expertise and its embodiment: Examining the impact of sensorimotor skill expertise on the representation of action-related text Psychonomic Bulletin & Review, 13 (4), 694-701 PMID: 17201372

Video Games Move From The Family Room To The Locker Room

It sounds like a sales job from a 12 year old; "Actually, Dad, this is not just another video game. Its a virtual, scenario-based microcosm of real world experiences that will enhance my decision-making abilities and my cognitive perceptions of the challenges of the sport's environment."  You respond with, "So, how much is Madden 09?"  

With over 5 million copies of Madden 08 sold, the release of the latest version two weeks ago is rocketing up the charts.  Days and late nights are being spent all over the world creating rosters, customizing plays and playing entire seasons, all for pure entertainment purposes.  Can all of those hours spent with controller in hands actually be beneficial to young athletes?  Shouldn't they be outside in the fresh air and sunshine playing real sports?  Well, yes, to both questions.


Playing video games, (aka "gaming"), as a form of learning has been receiving increased recent attention from educational psychology researchers.  At this month's American Psychological Association annual convention, several groups of researchers presented studies of the added benefits of playing video games, from problem-solving and critical thinking to better scientific reasoning.  

In one of the studies by Fordham University psychologist Fran C. Blumberg, PhD, and Sabrina S. Ismailer, MSED, 122 fifth-, sixth- and seventh-graders' problem-solving behavior was observed while playing a video game that they had never seen before.  As the children played the game, they were asked to think aloud for 20 minutes. Researchers assessed their problem-solving ability by listening to the statements they were making while playing.   

The results showed that playing video games can improve cognitive and perceptual skills.  "Younger children seem more interested in setting short-term goals for their learning in the game compared to older children who are more interested in simply playing and the actions of playing," said Blumberg. "Thus, younger children may show a greater need for focusing on small aspects of a given problem than older children, even in a leisure-based situation such as playing video games."

Also, in a recent article on video game learning, David Williamson Shaffer, professor of educational psychology at the University of Wisconsin-Madision and author of the book "How Computer Games Help Children Learn", argues that if a game is realistically based on real-world scenarios and rules, it can help the child learn.  “The question though is," Shaffer said, "is what they are doing a good simulation of what is happening in the real world?"  Shaffer explains the research happening on this topic at his UW lab, named Epistemic Games:





Support for this new era of learning tools is coming from other interesting people, as well.  George Lucas of Star Wars fame has an educational foundation, Edutopia, which has shown recent interest in simulation learning.  Here is their introductory overview and accompanying video:

There are some words of caution out there.  In a recent article, educational psychologist Jane M. Healy, author of "Failure to Connect: How Computers Affect our Children's Minds and What We Can Do About It," urges educators to proceed carefully.  "The main question is whether the activity, whatever it is, is educationally valid and contributes significantly to whatever is being studied," she says.  "The point is not whether kids are 'playing' with learning, or what medium they are playing in — a ball field or a Wii setup or a physics lab or art studio — but rather why they are doing it.  Just because it is electronic does not make it any better, and it may turn out not to be as valuable."

If we accept that there is some validity to teaching/learning with video game simulations, how can we move this to the sports arena?  Obviously, there is no substitute for playing the real game with real players, opponents, pressure, etc., but more teams and coaches are turning to simulation games for greater efficiency in the learning process.  If the objective is to expose players to plays, tactics, field vision and critical thinking, then a gaming session can begin to introduce these concepts that will be validated later on the field during "real" practice.  

This homework can also be done at home, not requiring teammates, fields, equipment, etc.  As mentioned in the videos above, another driving factor in the use of games is to reach this young, Web 2.0 audience through a medium that they already know, understand and enjoy.  The motivation to learn is inherent with the use of games.  The "don't tell them its good for them" secret is key to seeing progress with this type of training.


One of the best examples of video game adaptation for sports learning is from XOS Technologies and their modified version of the Madden NFL game.  In 2007, they licensed the core development engine from EA Sports and created a football simulation, called SportMotion, that can be used for individual training.  

With the familiar Madden user interface, coaches can first load their playbook into the game, as well as their opponent's expected plays.  Then, the athlete can "play" the game but will now see their own team's plays being run by the virtual players.  Imagine the difference in learning style for a new quarterback.  Instead of studying static X's and O's on a two-dimensional piece of paper, they can now watch and then play a virtual simulation of the same play in motion against a variety of different defenses.  With a "first-person" view of the play unfolding, they will see the options available in a "real-time" mode which will force faster reaction and decision-making skills.  

To take the simulation one step further, XOS has added a virtual reality option that takes the game controller out of the player's hands and replaces it with a VR suit and goggles allowing him to physically play the game, throw the ball, etc. through his virtual eyes.  Take a look at this promotional video from XOS:





XOS is winning some high praise for its system, including none other than Phillip Fulmer, Head Coach of the University of Tennesee football team.  “We’re leading the nation by taking advantage of this cutting-edge technology and we couldn’t be more pumped about it,” Fulmer said. “UT football has a long and storied tradition of success and because we look to pioneer groundbreaking concepts before anyone else, we’ll proudly continue that history. The XOS PlayAction Simulator begins a new chapter for UT and we’re pleased to add it to our football training regiment.” 

Albert Tsai, vice president of advanced research at XOS Technologies, says, “We’ve basically added functionality to popular EA video games such as customizable playbooks, diagrams and testing sequences to better prepare athletes for specific opponents.  Additionally, the software includes built-in teaching and reporting tools so that coaches Fulmer, Cutcliffe and Cooter can analyze and track the tactical-skill development of the team. At the same time, the Volunteers can experience immediate benefits because the familiarity with the EA SPORTS brand requires little to no learning curve for their players.”

So, the next time your son (or daughter!) is begging for 10 more minutes on the Xbox to make sure the Packers destroy the Vikings once again (sorry, a little Wisconsin bias), you may want to reconsider pulling the plug.  Then, send them outside for that fresh air.

Play Better Golf By Playing Bigger Holes

Here are some quotes we have all heard (or said ourselves) on the golf course or at the ball diamond.

On a good day:
"It was like putting into the Grand Canyon"
"The baseball looked like a beach ball up there today"

On a bad day:
"The hole was as small as a thimble"
"I don't know, it looked like he was throwing marbles"

The baseball and the golf hole are the same size every day, so are these comments meaningless or do we really perceive these objects differently depending on the day's performance? And, does our performance influence our perception or does our perception help our performance?

Jessica Witt, an assistant professor of psychological science at the University of Virginia has made two attempts at the answer. First, in a 2005 study, "See the Ball, Hit the Ball", her team studied softball players by designing an experiment that tried to correlate perceived softball size to performance. She interviewed players immediately after a game and asked them to estimate the size of the softball by picking a circle off of a board that contained several different sizes. She then found out how that player had done at the plate that day. 

As expected, the players that were hitting well chose the larger sized circles to represent the ball size, while the underperforming hitters chose the smaller circles. The team was not able to answer the question of causality, so they expanded the research to other sports.

Fast forward to July, 2008 and Witt and her team have just released a very similar study focused on golf, "Putting to a bigger hole: Golf performance relates to perceived size". Using the same experiment format, players who had just finished a round of golf were asked to pick out the perceived size of the hole from a collection of holes that varied in diameter by a few centimeters. Once again, the players who had scored well that day picked the larger holes and vice versa for that day's hackers. So, the team came to the same conclusion that there is some relationship between perception and performance, but could not figure out the direction of the effect. Ideally, a player could "imagine" a larger hole and then play better because of that visual cue.

Researchers at Vanderbilt University may have the answer. In a study, "The Functional Impact of Mental Imagery on Conscious Perception", the team led by Joel Pearson, wanted to see what influence our "Mind's Eye" has on our actual perception. In their experiment, they asked volunteers to imagine simple patterns of vertical or horizontal stripes. Then, they showed each person a pattern of green horizontal stripes in one eye and red vertical stripes in the other eye. This would induce what is known as the "binocular rivalry" condition where each image would fight for control of perception and would appear to alternate from one to the other. In this experiment, however, the subjects reported seeing the image they had first imagined more often. So, if they had imagined vertical stripes originally, they would report seeing the red vertical stripes predominantly.

The team concluded that mental imagery does have an influence over what is later seen. They also believe that the brain actually processes imagined mental images the same way it handles actual scenes. "More recently, with advances in human brain imaging, we now know that when you imagine something parts of the visual brain do light up and you see activity there," Pearson says. "So there's more and more evidence suggesting that there is a huge overlap between mental imagery and seeing the same thing. Our work shows that not only are imagery and vision related, but imagery directly influences what we see."

So, back to our sports example, if we were able to imagine a large golf hole or a huge baseball, this might affect our actual perception of the real thing and increase our performance. This link has not been tested, but its a step in the right direction. Another open question is the effect that our emotions and confidence have on our perceived task. That hole may look like the Grand Canyon, but the sand trap might look like the Sahara Desert!



Witt, J.K. (2008). Putting to a bigger hole: golf performance relates to perceived size. Psychonomic Bulletin & Review, 15

Brains Over Brawn In Sports

Sometimes, during my daily browsing of the Web for news and interesting angles on the sport science world, I get lucky and hit a home run.  I stumbled on this great May 2007 Wired article by Jennifer Kahn, Wayne Gretzky-Style 'Field Sense' May Be Teachable.  It ties together the people and themes of my last three posts, focusing on the concept of perception in sports.


Wayne Gretzky is often held up as the ultimate example of an athlete with average physical stature, who used his cognitive and perceptual skills to beat opponents.  Joining Gretzky in the "brains over brawn" Hall of Fame would be pitcher Greg Maddux, NBA guard Steve Nash and quarterback Joe Montana.  They were all told as teenagers that they didn't have the size to succeed in college or the pros, but they countered this by becoming master students of the game, constantly searching for visual cues that would give them the advantage of a fraction of second or the element of surprise.



Kahn's story focuses on two sport scientists that we have met before.  Peter Vint, sport technologist with the US Olympic team, who I highlighted in the post, Winning Olympic Gold With Sport Science,  comments on this, "In any sport, you come across these players.  They're not always the most physically talented, but they're by far the best. The way they see things that nobody else sees — it can seem almost supernatural. But I'm a scientist, so I want to know how the magic works."  So, Vint and his team continue to search not only for the secret to the magic, but how it can be taught.



Vint acknowledges the work of one of his fellow sport scientists, Damian Farrow, of the Australian Institute for Sport, who was part of the discussion roundtable mentioned in my post, Getting Sport Science Out Of The Lab And Onto The Field.


He is also fascinated with the perceptual abilities of elite athletes.  In his own sport, tennis, he wanted to know how expert players could return serves much better than novice players.  Similar to the research we looked at in an earlier post about tennis, Federer and Nadal Can See the Difference, Farrow designed an experiment that would try to identify the cues that players might need to instinctively estimate the speed and direction of a serve.  He had three groups of players, expert, non-expert but coached, and non-expert/non-coaced novices, wear ear plugs to block out the sound of the ball hitting the racquet as well as occlusion glasses that could block vision with the touch of an assistant's button.  

By changing the point of the serve at which the glasses would go black, and the players would be "blind", he could try to isolate the action of the server that the expert players might be tuned into that the novices were not.  The decisive point was immediately before impact between the racquet and the ball.  Arm and racquet position at that point seemed to let the expert players estimate the direction of the serve more accurately than the novices.


But Vint and Farrow are not satisfied just knowing what an expert knows.  They want to understand how to teach this skill to novices.  From his own competitive tennis playing days, Farrow remembers that if he consciously focused his mind on things like arm position, racquet angle, etc., he would be miss the serve as his reaction time would drop.  He understood that players need to not only learn the cues, but learn them to the point of "automaticity" through implicit learning.  

You may remember our discussion of implicit learning from the post, Teaching Tactics and Techniques in Sports.   Malcolm Gladwell, in his best-selling book, Blink, calls this implicit decision-making ability "thin slicing" and gives examples of how we can often make better decisions in the "blink" of an eye, rather than through long analysis.  Obviously, in sports, when only seconds or sub-seconds are allowed for decisions, this blink must be so well-trained that it is at the sub-conscious level.

For Vint and Farrow, the experiments continue, looking at each sport, but beyond the raw physical and technical skills that need to be taught but often times are the only skills that are taught.   

Understanding the cognitive side of the game will provide the edge when all else is equal.

Why The Offsides Flag Has Been "Ruud" to Italy

Two Euro 2008 games and two questionable offsides calls against Italy, one on defense, the other on offense, are still being talked about this weekend. First, in the Netherlands opener, van Nistelrooy scores from an obvious offsides position... except for Panucci, who is lying on the ground next to the goal. In fact, UEFA had to defend their referee for a correct interpretation. The call that did not get an explanation was Luca Toni's offsides on a cross from Zambrotta in the Romania match, which disallowed a first half goal. The first call was deemed correct, the second one was a blatant error.

Calling offsides correctly is one of the most difficult officiating duties in sports. In fact, some have argued that it is nearly impossible given the limitations of the human eye and the number of objects that need to be tracked by one assistant referee. Back in 2004, Francisco Belda Maruenda, M.D. of Centro de Salud de Alquerías in Murcia, Spain, took a look at the eye movements necessary along with their associated durations to determine if it was a humanly possible task. Let's look at his logic.

First, some eye physiology definitions are needed:
Saccadic movements - when we shift our eyes' focus from one object to another, we are making a saccadic movement. As an assistant referee (AR) looks from the ball carrier to the last defender to the offensive players, he needs to make several saccadic movements to take in the whole scene.

Vergence movements - there are two types, convergence (changing gaze from objects far away to objects closer to you), and divergence (just the opposite, near to far).

Accomodation - to change the focus of the eye from far to near or near to far, the convexity of the retina lens needs to change.

All of these eye movements, saccadic, vergence and accomodations take time to accomplish. Let's see how Maruenda added these up for an offsides call:

- the AR needs to keep track of at least four objects, the ball, the last two defenders and the offensive receiver of the pass. There may also be more offensive players to track as well.
- to make saccadic movements from the first object to each of the remaining objects will take about 130ms for the first object and then another 10ms per object after that. With four objects to track, that would be a total of about 160ms.
- if some of the players are on the far side of the field and some on the near side, then a vergence movement and an accomodation would be required, taking an additional 360ms for the accomodation and 640ms for the far to near vergence movement.
- of course, the players are constantly moving during the play, so their position is changing rapidly. If the speed of an offensive player is assumed to be 7.14 m/s, then in 100ms, they will have moved 71cm. This movement could be the difference between an onside position and an offside position. See the diagrams below (taken directly from the article)

Top: No offside, players in correct position.








Bottom: 100 ms later (players' velocity 7.14 m/s), offsides











The conclusion then, is that the total time needed for the AR to focus on at least four different objects in sequential order and process their positions cognitively is beyond the 100ms that would be needed for an offensive player to move from an onside position when the ball is played to a perceived offsides position when the AR finally focuses on him.

There have been some responses to Maruenda's logic, mainly centered on the fact that ARs have long known they can't watch the ball and the last defender, so they instead listen for the sound of the ball being struck while staying focused on the line of defense. This method may be used, but the sound of the crowd, the muted sound of the boot on the ball and the slower speed of sound may also have an effect on this judgement.

There is technology being developed to make offsides calls with multiple cameras, etc., but FIFA is not in favor of taking the flag away from the AR yet, just as they are against obvious goal line technology to watch for goals. It appears the debates and arguments will live on for the near future.



Belda Maruenda, F. (2004). Can the human eye detect an offside position during a football match?. BMJ, 329(7480), 1470-1472. DOI: 10.1136/bmj.329.7480.1470

Federer and Nadal Can See the Difference

Watching Roger Federer and Rafael Nadal battle it out in the French Open final and now again in the Wimbledon final, I started thinking more about the interceptive timing task requirements of each of their visuomotor systems... yeah, right. C'mon, I just needed a good opening line for this post.


However, other than a 120 mph tennis serve, take a second to think about all of the different sports that send an object flying at you at very high speeds that you not only have to see, but also estimate the speed of the object, the movement of the object and what you want to do with the object once it gets to you.



Some examples are:
- a hockey puck at a goalie (70-100 mph)
- a baseball pitch at a batter (70-100 mph)
- a soccer ball kicked at a keeper (60-90 mph)


Previously, we took a look at this in baseball and in soccer and also discussed the different types of visual skills in sports. There, we broke it down into three categories:

- Targeting tasks
- Interceptive timing tasks
- Tactical decision making tasks

The second category, interceptive timing tasks, deals with the examples above; stuff coming at you fast and you need to react. There are three levels of response that take an increasing level of brainpower.

First, there is a basic reaction, also known as optometric reaction. In other words, "see it and get out of the way". Next, there is a perceptual reaction, meaning you actually can identify the object coming at you and can put it in some context (i.e. that is a tennis ball coming at you and not a bird swooping out of the sky).

Finally, there is a cognitive reaction, meaning you know what is coming at you and you have a plan of what to do with it (i.e. return the ball with top-spin down the right line). This cognitive skill is usually sport-specific and learned over years of tactical training. Obviously, for professional tennis players, they are at the expert cognitive stage and have a plan for most shots. Federer's problem was that Nadal had better plans.

But, in order to reach that cognitive stage, they first need to have excellent optometric and perceptual skills. Can those skills be trained? Or are the best tennis players born with naturally better abilities? Did their training make them better tennis players or are they better players because of some natural skills?


Leila Overney and her team at the Brain Mind Institute of Ecole Polytechnique Federale de Lausanne (EPFL) recently studied whether expert tennis players have better visual perception abilities than other athletes and non-tennis players. Typically, motor skill research compares experts to non-experts and tries to deduce what the experts are doing differently to excel.

In this study, an additional category was added. Overney wanted to see if the perceptual skills of the tennis players were significantly more advanced than athletes of a similar fitness level, (in this case triathletes), to eliminate the variable of "fitness", and also more advanced than novice tennis players (the typical comparison). To eliminate the cognitive knowledge difference between the groups, she used seven non-sport specific visual tests. Please see the actual study for details of all the tests.

The bottom line of the results was that certain motion detection and speed discrimination skills were better in the tennis players (in other words, being able to track a ball coming at you and its movement side to side).


So, the expert tennis players were better at tracking balls coming at them than triathletes and non-tennis players.... seems pretty obvious(!) But, these results are a first step to answering the question of "can these skills be trained"? We see that there is, indeed, a difference in ability level between expert players and athletes that are in similar shape and competitive spirit. Now, the question becomes, "how did these tennis players acquire a higher level of perception skill"? Was it "nature or nurture", "genetically gifted or trained through practice"?


Source: Overney, L.S., Blanke, O., Herzog, M.H., Burr, D.C. (2008). Enhanced Temporal but Not Attentional Processing in Expert Tennis Players. PLoS ONE, 3(6), e2380. DOI: 10.1371/journal.pone.0002380

See The Ball, Be The Ball - Vision and Sports

The whistle blows and Shaq goes to the line again after being fouled on purpose for the fourth time. And, again, we watch as he takes that awkward stance, looks at the basket and then clanks one of the back of the rim. We wonder how hard this can be... just aim and shoot! Isn't it that simple? Well, not exactly. In our introduction to this series I mentioned the research of Dr. Joan Vickers and her concept of the "Quiet Eye". In her book, Perception, Cognition and Decision Training, she describes this visual targeting pathway:


"...the visual pathway begins when information is registered on the eye's retina by the focal and ambient systems, then travels to the back of the head along the optic nerve and radiates to the occipital cortex, where visual information is registered as billions of features. These then race in parallel fashion both to the top of the head to the parietal cortex (dorsal) and along the sides of the head to the temporal (ventral) areas. There is an integration of information in the somatosensory cortex as the information goes to the frontal cortex, where the goals and intentions reside and plans are formulated for the specific event that is occurring. The flow of information then goes to the premotor and motor cortex at the top of the head before going down the spinal cord to the effectors." P.26


This same process repeats constantly during any athletic event and it is the most critical determinant of the outcome of the game. Just think about the types of visual work that needs to be done by an athlete (as defined by Dr. Vickers):

1. Targeting Tasks - being able to fixate on a target, fixed or moving, to be able to throw, kick or send an object towards it. (i.e. Shooting or passing a baseball, football, basketball, soccer ball, hockey puck, etc.)

2. Interceptive Timing Tasks - being able to recognize, track and finally control an object as it comes at you (aka "catching")

3. Tactical Decision Making Tasks - being able to take in an environmental scan of the field/court and recognize patterns of all the moving objects (i.e. a quarterback scanning his receivers and choosing the best option for a pass).

All of these scenarios require the athlete to focus or "gaze" on the right points in the environment and ignore the rest of the scene. Dr. Vickers' work has been to observe athletes of different skill levels, expert and non-expert, and define the "best practices" of visual control so that the non-expert athletes can be coached to better performance. Her research lab uses "eye-trackers" (see photo) to monitor the focus and gaze of the athlete's pupils as they perform their skills.

For example, she has found that expert baseball hitters focus on the release point of the ball exclusively, rather than random fixations on the pitcher's arm, head, jersey, etc. She found that expert golf putters focus on a specific point on the cup, then a specific point on the back of the ball and remain fixated on the point on the ball after the ball has left the putter blade.

Novices allow their gaze to wander from the ball to the hole, without a very specific focal point on either the cup or the ball. The term "Quiet Eye" comes from these observations that expert performers have consciously chosen points in their space to focus on rather than allowing their eyes to wander and fixate on multiple points (i.e. a "noisy" eye).


So, why does the Quiet Eye work? When we fixate on key points in our field of vision, how does this help our neuromuscular systems perform better? The subconscious part of our brain may be recognizing a pattern that we have seen and experienced before and directing our movements based on this information. Some have called this "muscle memory", meaning our brain has learned through repetition and practice how to throw a ball to a moving receiver at that distance and speed, and so, when presented with a similar scenario, knows what to do. Think about when you shoot a jump shot and sometimes you get that sensation, as soon as it leaves your hand, that the ball is going in. Your brain may be telling you that, based on past experience, when you've executed the same aim and same muscle movement then the ball has gone in.

This takes us back to the discussion we had in our previous post on baseball fielding regarding theories of perception-action combinations. The Information Processing model claims that we perceive the environment first through our senses, primarily our vision. Then, we access our memory to find the rules, suggestions and knowledge that we have gained from past experiences and these memories guide our action in the moment.

The Ecological Psychology model removes the memory access step and claims that our perception of the environment leads directly to our actions, as there is not enough time to access our lessons. If that is true, then how does the Quiet Eye help us? It seems the Quiet Eye is what we need to connect the current scenario (standing on the free throw line looking at the basket) with our lessons learned from the past (how we made this shot hundreds of times before). Research continues on this question and I'm sure we'll come back to this in future posts.


Next time, I will take a look at Dr. Vickers' "Decision Training Model", which builds on the Quiet Eye theory to train athletes to improve their tactical in-game decision making. We will look at the athletes who are known as having good "vision of the field" and how to raise everyone's game to that level.

So Why Can't Shaq Make Free Throws?

The NBA league average for free throw shooting is about 75%. Shaquille O'Neal's career average is 52.4%. Even worse, Ben Wallace's career average is 41.9%. The average for the NCAA Division 1 teams is 69%. The obvious question is why can't Shaq or Ben or Memphis do any better, but the bigger question is why do most of the best basketball players in the world miss 2 or 3 free throws out of 10? Maybe they just haven't heard about Joan Vickers and the "Quiet Eye".

For me, the best science is applied science. The same goes for sports science. Theories, physics, psychology, etc. are only useful in sports if they can be used to improve in-game performance. That's why I have always been a fan of academic work that leads to useful techniques in the field. Professor Joan Vickers of the University of Calgary has been applying her research into the human visual system and its effects on sports performance for over 25 years. She is the discoverer of the "Quiet Eye" skill that has been shown to significantly improve accuracy in targeting and decision-making skills in many sports. In addition to this "gaze control" technique, she also has developed a 7-step teaching process to improve the in-game decision-making of athletes, based partly on their visual perception skills.

She has a new book out that condenses all of these ideas, called Perception, Cognition and Decision Training. Over the next few days, I will do my best to paraphrase and explain the most useful information and techniques, but of course the best source is this book.
For an opening primer on the Quiet Eye, please take a look at this episode and this online video of PBS' Scientific American with Hawkeye himself, Alan Alda, shooting free throws.