Part 1

One day all elite athletes will have their Dynamic Visual Acuity checked and improved.  Until that day, all I can do is present evidence of how important it is and how limited the human eye is in the hyper fast, hyper difficult world of tennis.

Part 1 is an astute investigation of the science and practice of professional line calling.  An article that helps describe how difficult a task tennis presents for the human eye.  Incredibly, this is just for the poor linesmen who are sitting still trying to focus on one bounce of the ball in one spot.  Linesman are actually told to NOT watch the ball!  Wow!

In stark contrast to this trained professional linesman, most line calls in our sport are made by players who are running, out of optimal position, and probably feeling obligated to their doubles partner.  No wonder the demands can get out of control and cause friction among friends!

Part 2 is an article to help put the Part 1 description into practical application for your tennis.  The pros now have the benefit of Hawk Eye technology, the rest of us do not.  Hopefully, these articles will help you find the proper perspective on your next line call.

~Best of luck with your tennis!

Jonathan
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THE INS AND OUTS OF BORDERLINE TENNIS CALLS
By Alan Schwarz
Published: June 23, 2009, NewYorkTimes.com

When a line judge at Wimbledon rules on a hair-splittingly close call and says the ball is out, the inevitably disgruntled player should not only consider challenging the call for review by digital replay system. He should consult a recent issue of Current Biology.

A vast majority of near-the-line shots called incorrectly by Wimbledon line judges have come on balls ruled out that were actually in, according to a study published in October by researchers at the University of California-Davis. To the vision scientist, the finding added to the growing knowledge of how the human eye and brain misperceive high-speed objects. To the tennis player, it strongly suggests which calls are worth challenging and which are best left alone.

The researchers identified 83 missed calls during the 2007 Wimbledon tournament. (Some were challenged by players and overruled, and others were later identified as unquestionably wrong through frame-by-frame video.) Seventy of those 83 calls, or 84 percent, were on balls ruled out — essentially, shots that line judges believed had traveled farther than they actually did.

Called perceptual mislocalization by vision scientists, this subconscious bias is known less formally to Wimbledon fans as “You cannot be serious!” — John McEnroe’s infamous dissent when, yes, a 1981 shot was ruled out. Now that players can resort to a more evolved appeal procedure, the researchers’ discovery suggests that players should generally use their limited number of challenges on questionable out calls rather those that are called in, because such out calls have a far better chance of being discovered as mistaken on review, then overturned.

“What we’re really interested in is how visual information is processed, and how it can be used to a player’s advantage,” said David Whitney, an associate professor at U.C.-Davis’s Center for Mind and Brain and the paper’s lead author. “There is a delay of roughly 80 to 150 milliseconds from the first moment of perception to our processing it, and that’s a long time. That’s one reason why it’s so hard to catch a fly — the fly’s ability to dance around is faster than our ability to determine where it is.”

This is the third Wimbledon in which players can challenge questionable calls for review by the Hawk-Eye system, which uses high-speed video cameras to record balls’ flight. (About 25 percent of all challenges result in overturned calls.) There is no cost to the player when a call is proved correct, but after three such episodes in a set a player may not challenge again. Whether through strategy or residual tennis etiquette, most players leave many challenges unused.

Theoretically, line judges should be equally prone to call an out ball in as they are an in ball out. But when objects travel faster than humans’ eyes and brains can precisely track them — for example, Andy Roddick’s 150-mile-per-hour serves — they are left having to fill in the gaps in their perception. In doing so they tend to overshoot the object’s actual location and think it traveled slightly farther than it truly did.

Both successful challenge calls as well as the overlooked mistakes that the researchers later identified were several times more likely to come on “long” calls than “in” calls. (The same pattern existed at Wimbledon last year, Whitney said, although the paper did not present that data.) So players are better off using as many challenges as possible on balls called out, because those are the calls most likely to be wrong; if a player thinks an “in” call was wrong, chances are his own eyes were as fooled as line judges’ sometimes are.

Without knowing it, tennis officials are already told to try to compensate for this mislocalization effect. Published instructions for United States Tennis Association line judges tell them to “focus your eyes on the portion of the line where the ball will land,” rather than attempt to track the ball in flight. “Get to the spot well before the ball arrives,” they are advised.

Rich Kaufman, the association’s director of officials and a linesman and chair umpire from 1976 to 1997, said that of all things “one of the hardest things to teach new linesmen is to take their eye off the ball.”

“I once asked an eye doctor, then what am I seeing on a bounce?” Kaufman said. “The doctor said that’s your brain working — you think you see the initial point of impact but it’s the blur of the entry and exit of the ball.”

A player using his knowledge of this effect in challenging calls could see a benefit of about one or two overturned points per match, Whitney said, plus any psychological boost from feeling vindicated rather than robbed. But Whitney added that understanding how the brain misperceives visual stimuli can help in more real-life matters, like the design and placement of high-speed safety equipment, automobile brake lights and warning signs of all types.

As for Wimbledon, it appears as if the new information can only help players, not the judges who vex them. Kaufman said: “You have to call what you see. Or what you think you see.”

Part 2

HANDLING LINE CALLS FOR RECREATIONAL PLAYERS

by Jonathan Bailin, Ph.D.

Over the years, I have addressed this issue verbally with recreational players from time to time.  It is
so important to them however, that it should be placed here for future reference….

Strong, successful personalities often treat recreational tennis as just another litmus test of
their personal success.  That their competitive nature in business should be reflected in all arenas
of their lives.  Why not tennis?

Because by definition, it is “recreation”.  An important word to keep in mind on court.

I hope you have had a chance to look at the above article on eye skills and line
calling I reproduced from the NY Times.  VERY RARELY are bad line
calls on purpose in amateur tournament tennis, and practically never in social tennis.
That said, they are an ever present artifact of imperfect eye sight for all players and officials.

It’s clear that some players become hypersensitive to line calls in general, but a more “recreational”
and relaxed approach to this situation is in order.  Here is an adult, big picture approach:

No one wants our favorite sport to have any adverse effect on our friendships.   Recreational
players are important cogs in each others social wheel.  Your goal should be to have many years
of amicable social and competitive tennis ahead, with all players available, at your skill level.

====>  To that end, I propose you use a new line call policy on court– If an opponent even looks at you
funny after you make a call, give the point away!  <======

This can be confusing and difficult at first, but it is an important response for all tennis players.

First, admit to yourself that if you are not making a living on tour, no matter what “competition”

you are engaged in, you are playing “social tennis”.  That is you are in a very small, tightly knit

community which communicates frequently about ALL aspects tennis.  More important than any

trophy or team success, your reputation as a mature person, who others enjoy playing with, is at stake.

Social tennis should test skills, not reputations, because tennis should not be at that

level of importance in our lives.  Your business, your family, your contributions to the people

around you, the planet, and your health are that important.  Not tennis!

In my professional opinion, suggesting to “Replay the point” is not a strong enough gesture of capitulation to
an opponent who has just taken a risk by questioning a call verbally or by body language.  Keep
in mind that they already feel awkward.  Your choice is to help them relax by showing an expert
understanding of the situation or heighten their fears that they will face ridicule or rejection.

ALL PLAYERS SHOULD RESPOND TO THAT SITUATION BY– asking for their help in making the call “if you saw it more clearly than I did” and graciously, with genuine intent, offer them the point.  Let THEM offer to play the point over and do not offer that option yourself.  If you are going to capitulate graciously, go the whole way!

This does several things.  One, it demonstrates that you understand the challenges for the human eye.  Two,
you are mature enough to have your priorities straight in terms of life and the future fun to be had with these same friends, in the next point, and in the next match.  Three, that the continuity and spirit of the contest is more important
to you than any particular point.  Even match point!

The pros know that one point matters as often as…. ummm…. Halley’s Comet!  In that case, the line judge’s
job is to take the grief anyway.  For recreational players, one point matters even less often.

Relax and enjoy your friends!

As background, “static vision skills” are those tested by a typical Optometrist. They are used to read efficiently or see objects clearly at a variety of distances. For example, though this page does not move, your eyes have still learned to recognize the letters, comprehend their meaning, and move smoothly from line to line. A set of skills that can be improved if desired. The movement in these “static” movement skills are related to those required for tennis.

Original Research

Visual Skills of the Human Eye

by Jonathan Bailin, Ph.D. & Dr. Gary Polan, O.D.
Exercise Physiology/Biomechanics/Ergonomics
Sports Medicine & Ergonomics Associates

Submitted in 1997

The author has collaborated with his associate, Dr. Gary Polan, O.D. many times.  Dr. Polan is a pioneer in the field of Sports Vision Training (SVT) and/or Vision Training (VT) since 1984 (*).  In 1996, his work received corroboration by the staff at the Jules Stein Eye Institute at the UCLA Medical School (**).  Here, we will outline all the individual skills required by the visual system to perform at its peak that now form the science of VT and SVT.

Dr. Polan’s experience in training and improvement of visual skills has resulted in “surprising” advances in most learning disabled cases.  Improvements in intellectual activity which are generally unexpected, but very welcomed by parents, have not been well documented by rigorous research designs to date.  Still, we are confident that a product like Sportwall will play a significant role in improving reading skills, Attention Deficit Disorder (ADD), and Dyslexia.

Few realize that reading is a motor activity like sports!  Just one of the many common reading flaws is transposing letters like “ea” to “ae”.  When the number or severity of flaws effects performance or comprehension, VT or SVT is warranted.

So, before any improvement in reading or athletic performance can take place the visual system must be engaged.  What are the exact skills that the eyes posses that can influence performance?

Introduction to Visual Skills

First, readers of this proposal should realize that ALL visual skills are learned. From infancy, the vision skills that we take for granted have been built gradually over time.  Contrary to folklore, the are not precisely genetically predetermined and can be improved.

Fact:  visual skills, no matter how polished by a our activities or sports, can be improved in a clinical or private practice setting.  Sports careers, worth millions of dollars, can be improved and lengthened past their usual expirations.  One of Dr. Polan’s more famous patients Carl Lewis, says that more of his records would still be standing today had he experienced SVT during his competitive career.

Visual skills can be divided into 3 sub areas: Visual Acuity, Visual Efficacy, and Visual Processing. Visual Acuity is measured by standard optometric tests commonly used for eye prescriptions including standard eye chart examinations.

Visual Efficacy can be measured by testing among the 24 areas listed below which include focusing, convergence, divergence, etc. Visual Processing can be evaluated by tests which measure the extent of learning disabilities such as Reading Disorders, Attention Deficit Disorder (ADD), and Dyslexia as found in items 2, 7, I5, 16, 18, 20, 21, 22, and 24. Most ADD and Dyslexia is responsive to treatments for visual/perceptual deficiencies in these areas of training thus often diminished or alleviated completely.

Visual Efficacy Skills

All movement mechanics during sports are enhanced by eye skills and eye health.  In turn, improvements in several areas of eye skills will enhance eye performance during motor activity.  For example, reaction time is first dependent on the visual accuracy and recognition skills listed.  To acquaint the reader with the proposed research, a brief review of each eye skill which can positively effect motor performance must be considered.  Please note that Visual Efficacy Skills are a subset of all the visual skills listed below.

VISUAL SKILLS

1) Visual Acuity-your ability to achieve a sharp resolution of an image can be divided into static acuity (stationary images) and dynamic acuity (resolution of images in motion).

Static Visual Acuity–Corrected or not, your eyes should have 20/15 vision for high speed activities. “20/15” vision means that is you see at 20 feet what the average person only sees accurately at IS feet away.

Dynamic Visual Acuity–the ability to see sharply while the player, opponent, and ball are all in motion. This ability is made up of many other skills such as Convergence, Focusing, Tracking, and Interpretation, etc. Following the action with the eyes rather than the head or body is more efficient and puts less stress on the balance and muscular-nervous system.

2) Visualization—is the ability to plan, imagine, and prepare for upcoming motor skills and movements.  Some sports scientists believe visualization of needed skills is more efficient than coaching “pep talks”.

3) Peripheral Vision–is critical to awareness of other important things while watching the ball such as your teammates, boundaries, or opponents.

4) Depth Perception—is the ability to quickly and accurately judge the distance between yourself and your opponent, teammates, targets, and boundary lines while judging the speed, rotation, and flight path of the ball.  Billy J King rates this above court speed and eye-hand coordination for junior tennis players.  Quickly diminished by those who stare during the day-students, programmers, and executives may play poorer tennis during the week than week end for this reason.

5) Visual Pursuit—is the ability to use the eyes to follow a moving object smoothly and accurately. This critical skill is based on good eye teaming and eye muscle balance but it cannot track a ball smoothly at high speeds where Saccadic Movement takes over.

6) Saccadic Movement-is the ability of the eyes to “jump” from one point to another when speeds exceed those of visual pursuit. This skill is used in reading to jump from one word to the next. If this skill is poor, reading ability is affected!  Quick, accurate saccades are used to survey rapidly with as little head movement as necessary. Head movement is a less efficient method of eye tracking and can confuse balance.  Unnecessary head movements, and eyelid reflexes to flinch, must be overcome with training.

7) Visual Concentration-describes the cooperation between Visual Pursuit, Saccadic Movement, and Visualization in the “minds eye” or imagination. This skill is not scientifically well defined yet, but is exemplified by tennis players who must switch concentration rapidly from target, to ball, to processes of planning and prediction which are critical to performance.

8) Speed Of Focusing-is the ability to shift focus from near, intermediate, and far distance. This eye muscle skill is subject to the same fatigue which affects other muscles over the course of exercise.

9) Glare Recovery Speed-is the ability to see clearly after looking toward intense light. Focusing near sun, and at tennis court lights, causes “dazzle” to the retina.

10) Sight in dim illumination.

11) Eye Muscle Stamina-is the ability to withstand fatigue without decreased performance in a variety of eye tasks.

12) Color Perception—is not critical but may play a role in optic yellow against white lines and line calls.

13) Eye Dominance—is the ability of the sight in one eye to dominate images from the other.  Tennis players generally prefer strokes on the same side as the dominant eye which is usually the right, for right handed players, over 80% of the time.

14) Fixation Ability-is the skill of preventing eye fatigue which comes from staring at objects too long. Receivers with poor fixation skills fatigue within a few seconds of staring at the server.  Other players do not, but staring should be avoided.

15) Visual Memory—is the accumulation of past experiences such as the number of proper swings logged in a players “motor program file”. This combined with visualization for future swings is probably a major factor in consistency during competition. Visual memory fades with time.

16)  Spatial Localization-Knowing your position relative to other objects especially while you, ball, and opponent are moving.

16a) Esophoria—players who see the world CLOSER than reality, tend to hit/throw shorter.

16b) Exophoria–players who see the world FARTHER than reality, tend to hit/throw longer.  We believe Shaquille O’Neal was a good example of this.

17a)  Speed of Recognition Time-is how fast can you identify images.

17b) Reaction Time–How fast can you react to those images.

18) Eyes to Body Coordination–is the ability to integrate what you see into an appropriate and coordinated response from your body parts (aka: Visual/Motor Integration).

19) Contrast Sensitivity—the ability to pick out an important object against a field of other objects.

20) Visual Attention-is the skill used to prepare the eyes and brain which heightens its readiness for an upcoming task. This is a precursor to Visual/Motor Organization.   Of course, the body can influence this system which is one reason why elite tennis players bounce during the opponents contact.

21) Figure/Ground–is the ability to pick out an object in the foreground against a variety of background fields; to discriminate the figure to be attended to and to see the interrelationships to its background information.

22) Visual/Motor Organization–is the ordering and organization of motor skills; to choose from a “catalog” of motor programs for meaningful and productive action.

23) Jump Duction–the ability to move from visual tasks that require convergence to divergence of the eyes and back.  Jump Duction deals with vergence; the activity of the extraocular muscles to diverge for distance, and converge for near objects rapidly and efficiently.

24)  Auditory/Tachistoscopic Skills— are those which help sound and sight skills complement each other during visual processing. It is the auditory/visual integration ability of an individual which coordinates inputs into a meaningful perception and to shift priority and attention from one to the other when necessary.  Years ago, preventing air traffic over the US Open tennis tournament in New York was initiated for this reason.  Players had to hear the serve as well as see it.

Auditory specialists can better assess the ability to discern background from foreground sounds similar to the way we will assess background to foreground objects. This is an area worthy of much more study. There is much potential to design audio triggers, cues, and scoring tones here.  Consider the bell for a horse race!

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The list of “Visual Skills” above items 1-24 is Copyright (c) Jonathan Bailin. Ph.D. 1997. Reproduction by author’s permission only.

* Hoflinan, L., Polan, G., Powell, J. The relationship of contrast sensitivity functions to sports vision” Journal of the American Optometric Association 55:10,747-752, Oct 1984.
** Laby, Rosenbaum, Kirschen, Davidson, Rosenbaum, Strasser, Mellman “the visual Function of professional baseball players” American Journal of Opthalmologv 122:4,476-485. Oct. 1996.

Keywords:  sports vision training, SVT, vision training, VT, eye skills, reading skills, sports performance, sports career enhancement, visual acuity, visual efficacy, motor learning, eye performance, eye health