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JoeW
11-24-2012, 08:36 AM
Kahn, AZ and Crawford, JD. (2001). Ocular dominance reverses as a function of horizontal gaze angle. PubMed.
In a reach-grasp task for targets within the binocular visual field, subjects switched between left and right eye dominance depending on horizontal gaze angle. On average, ocular dominance switched at gaze angles of only 15.5 degrees off center.http://www.ncbi.nlm.nih.gov/pubmed/11369037?dopt=Abstract

Quartley, J and Firth, AY (2004). Binocular sighting ocular dominance changes with different angles of horizontal gaze. PubMed.
A change in eye dominance occurs when viewing in the contralateral field. Differences may exist in the angle at which this occurs due to the different conditions of the various tests for ocular dominance. http://www.ncbi.nlm.nih.gov/pubmed/14998366?dopt=Abstract

The research summarized above indicates that eye dominance can and does change as one moves into a pool shot from across the horizontal field. For some people when they move into the shot making position from the left or from the right their eye dominance shifts as they look at the sighting point.

The obvious solution to this shift in dominance is to walk into the shot from behind. While you may be looking at the shot from the side as you walk to it, you probably should not begin to sight the shot until you are in position and take a step back. This will place you on the shot line, yield a better perspective, and will give your eyes and their dominance preferences time to adjust to the visual field directly in front of you. This type of recommendation has been around for a long time and is now reinforced by the research literature.

Whether you choose to place the cue under the dominant eye or allow the brain to compensate for the dominant eye is another choice. The research literature seems to imply that shift in dominance in the lateral and contra-lateral field is not an invariant process across people: Some people experience more of a shift than others. If you have noted this shift in dominance and or a change in dominance then it is probably more important for you to step back when on the shot line and look directly in front of you prior to sighting.

A more extensive literature review on this topic would probably yield even stronger evidence as we are dealing with a physiological process offset by mental preferences. Pool instructors should seriously review this literature and it probably should be a standard recommendation based on solid research findings. While some people may not have a lateral shift in dominance the recommendation to take a step back allows one to gain a better perspective.

JoeW
11-24-2012, 08:52 AM
Sleep may effect ocular dominance
http://esciencenews.com/articles/2009/02/11/sleeping.brain.still.hard.work.mechanisms.consolid ation.cortical.plasticity

Anti-obesity drugs may effect ocular dominance plasticity
http://esciencenews.com/articles/2008/05/07/study.suggests.caution.a.new.anti.obesity.drug.chi ldren

General intro to eye dominance shifting
http://www.sharp-sighted.org/index.php?option=com_content&task=view&id=82&Itemid=149

The Renfro
11-24-2012, 09:13 AM
Thanks Joe!!! Now maybe the people that think it's not important can understand for some of us it is =)

One Pocket John
11-24-2012, 10:33 AM
Just read

http://www.sharp-sighted.org/index.php?option=com_content&task=view&id=82&Itemid=149

I am right handed and right eye dominent.

I performed the "Miles Test" using a CD on my pool table looking at a ball at
about 18" away and then a ball at about 8' away.

What I noticed was on the closer ball as I brought the CD closer to my head was that the hole came right into my right eye. When I used the CD on the ball that was 8' away and brought the CD closer to my head the hole ended up closer to the bridge of my nose.

I gotta do some more testing on this. In fact I think I'll do the test in the shooting position to see what happens.

Thanks for the thread Joe

John

ENGLISH!
11-24-2012, 10:52 AM
John,

I just did the test & since I was on-line I did it with my reading glasses on. The glasses are the weakest .25 'dollar store' type so I can still see welll with them at some distance. I was shocked that the close up object results were similiar to yours. Then I 'real eyesed' that I had my glasses on. So, I did it again without them several times & I am right eyed. The reading glasses thing was interesting though.

Regards,

JoeW
11-24-2012, 11:01 AM
The development of the visual grid and the origin of ocular dominance indicates that there are horizontal and vertical dimensions to ocular dominance.

http://www.sharp-sighted.org/index.php?option=com_content&task=view&id=39&Itemid=93

I have not found a study that address the shift in ocular dominace along the vertical axis. Most of these studies are more concerned with the topographical brain mapping and ontological development. However. it would tentatively appear that ocular dominance can shift along the vertical axis.

This may lead to the idea that dominance can also shift as one moves from the standing position to the bent over position. Maybe, maybe not. At any rate it would be good to in some way determine if the sight picture is different with regard to ocular dominance from these two positions.

My personal preference has been to continuously stare at the target while bending over. I know the perspective changes and have thought the brain developed a "better" sight picture if one watched the target while bending over. When the target is fixed in my visual field then I go into the rest of the pre-shot routine.

Now I wonder if there is any sort of shift in dominance from one position to the other. The stereotaxic figures in the article referenced shows that visual representations are variously located for the vertical plane.

With different physical locations I would expect the development of different patterns of representation.

And of course, this supports my opinion that one should watch the target as they bend over for any changes in perspective and to account for the parallax problem.

I used the Miles test while bending over and saw what appears to be slight shift in ocular dominance. I can't rule out confirmatory bias so it may or may not be true. An "n" of one is simply not sufficient. If true it implies that sighting may be different from the standing position than it is from the shooting position.

JoeW
11-24-2012, 11:19 AM
And of course all these studies confirms my initial position that the brain "knows" how to adapt to ocular dominance. In my thinking it is best to pick a reference point, such as the center of the chin, and let the brain take care of the rest. Stepping into the shot line and continuously staring at the target while bending over only facilitate the brain's natural abilities.

Your milage will definitely vary.;)

JoeW
11-24-2012, 11:32 AM
Just read

http://www.sharp-sighted.org/index.php?option=com_content&task=view&id=82&Itemid=149

I am right handed and right eye dominent.

I performed the "Miles Test" using a CD on my pool table looking at a ball at
about 18" away and then a ball at about 8' away.

What I noticed was on the closer ball as I brought the CD closer to my head was that the hole came right into my right eye. When I used the CD on the ball that was 8' away and brought the CD closer to my head the hole ended up closer to the bridge of my nose.

I gotta do some more testing on this. In fact I think I'll do the test in the shooting position to see what happens.

Thanks for the thread Joe

John

Though I have not read any studies that indicate that ocular dominance shifts over various distances from the eye, it makes sense that this would happen as the perspective changes and the eyes would accommodate to this change with a change in emphasis based on eye preferences.

While visual preferences are indeed a real phenomena I think that we need to respect the brain's ability to deal with physical changes in the environment as seen from changing body positions.

For those who are curious, you can conduct a version of the "Miles Test" by over lapping your thumbs and index fingers to make a small hole. Hold your arms extended and look at some small object. Close one eye and then the other eye. With monocular vision you will see different pictures. The amount of difference will show you the preferences your individual eyes have for sighting an object.

You can try the test with objects at various distances and located at various places in the horizontal and vertical planes to see if you have any shift in ocular dominance.

Sighting an object through a CD is a better way to get a standard for comparison.

chevybob20
11-24-2012, 11:49 AM
I've found that I can make my eye dominance shift with motion. Perform the Miles test but move the card with the hole rapidly into place from right to left with both eyes open, then close an eye to see which is dominate (mine will be the left eye). Repeat the test from the other direction and see what happens.

3andstop
11-24-2012, 12:03 PM
This is all way over my head, but I can tell you there was a period in my play that really stressed my confidence level while shooting long shots with any angle other than straight in at moderate to soft speed.

When I walk into a shot I get down on it and after honing in my stroke, I focus on the object ball as I stroke the shot.

While staying down on the shot and seeing the CB into the spot on the OB that I shot at, my eyes see the shot at about the halfway point as being way off line. so much off line that I'm going to miss by a full diamond.

Then as the CB contacts the OB it is a perfect hit right on the target I aimed at.

I have learned to trust my aim prior to contacting the CB and allow myself to totally disregard this optical illusion I see on these shots.

I dunno if this is relative to your post but thought it would be of interest.

JoeW
11-24-2012, 12:14 PM
I use a similar procedure 3andstop. I reinvented the wheel and was later told that golfers use this trick. They call it an intermediate target and it is what I too use. On long shots I select a spot on the table about half way to the target and then try to line up the CB, intermediate target, and the contact point. When I feel that these three are lined up I make the shot effortlessly, Well only if I follow my PSR.

JoeW
11-24-2012, 12:16 PM
I've found that I can make my eye dominance shift with motion. Perform the Miles test but move the card with the hole rapidly into place from right to left with both eyes open, then close an eye to see which is dominate (mine will be the left eye). Repeat the test from the other direction and see what happens.

Apparently eye dominance changes in all three dimensions and with movement. This could become a very difficult topic. Reminds me of the idea that I should not run with scissors. :grin:

3andstop
11-24-2012, 12:23 PM
I use a similar procedure 3andstop. I reinvented the wheel and was later told that golfers use this trick. They call it an intermediate target and it is what I too use. On long shots I select a spot on the table about half way to the target and then try to line up the CB, intermediate target, and the contact point. When I feel that these three are lined up I make the shot effortlessly, Well only if I follow my PSR.


Joe, I don't so much use an intermediate target, but rather have trained myself to disregard the optical illusion I see as the CB is halfway to its target.

I've learned to trust that my original aim line at the CB, prior to shooting is correct, and that has regained my confidence in pocketing the ball.

In the years past, this was one aspect of my game that mentally held me back as I was unsure I was online initially. Now, I realize that what I see when the CB is at its halfway point toward the OB is irrelevant and my original aim line and envisioning of the shot is accurate.

The reason I see the tracking of the CB so off at the midway point, I'm assuming has to do with depth perception and eye dominance. It is just such a strange phenomenon that it took a lot of play to overcome that mental block to my shot making confidence. :)

chevybob20
11-24-2012, 01:16 PM
Apparently eye dominance changes in all three dimensions and with movement. This could become a very difficult topic. Reminds me of the idea that I should not run with scissors. :grin:

The solution that I've found (so far) is exactly what you said. I come in from straight be hind the shot after initial sighting while standing. I have found that if I keep the cue in my peripheral vision while standing and then watch it come in from the left while bending in for the shot helps. Also, everything I do including sighting while standing must be part of the PSR.

peteypooldude
11-24-2012, 03:41 PM
So..... There's an over 50% chance that you should just let the eyes take care of their selves?

3kushn
11-24-2012, 04:18 PM
Think this adds any credibility to what Geno teaches?

KCRack'em
11-24-2012, 10:46 PM
I'll dig into this later, but I want to put this out there first:

I was decent player before I left the game for several years. Back then my left eye wasn't very useful. It was hard to correct so I gave up trying. I had learned to compensate very well, and could throw, catch, shoot a basketball, etc. very well. I played pool pretty well considering that I wasn't a student of the game and just picked it up in bars/on campus.

Fast forward into my college years (after active duty) and a local teenager (one of the best players in the area) asked me if I was blind in my left eye. He watched me shoot and noticed that my cue was very much in line with my right eye. I didn't realize I was doing it.

Not long after college I lost interest in the game and stayed away for most of about 8 years.

Just over two years ago I had cataract surgery and now have far better vision in the left eye than I can recall at any point in my life. I wear glasses now and have some correction for both eyes. If both are fully corrected, I see double. It's called vertical imbalance. My prescription glasses are tweaked to allow my right eye to be dominant. I just had another exam a few days ago, and the vertical imbalance hasn't improved. The Doc said he uses a prism to keep it at bay. I'm not entirely sure what that means......

It was after surgery that I decided to start playing again.

I play okay, but it really is different seeing well with both eyes. I could wear bifocals, but choose instead to take my glasses off for up close work. I have prescription reading glasses, but seldom need them. I do wear my glasses to shoot pool.

I know it's a novel, but I would like to read advice/ideas about how to play to overcome this. The game was so much easier before. I don't mind that it's more of a challenge. By the way, I mentioned some other sports because I can't catch a frisbee or anything like that the way I used to. It sucks!

chefjeff
11-25-2012, 06:44 AM
The development of the visual grid and the origin of ocular dominance indicates that there are horizontal and vertical dimensions to ocular dominance.

http://www.sharp-sighted.org/index.php?option=com_content&task=view&id=39&Itemid=93

I have not found a study that address the shift in ocular dominace along the vertical axis. Most of these studies are more concerned with the topographical brain mapping and ontological development. However. it would tentatively appear that ocular dominance can shift along the vertical axis.

This may lead to the idea that dominance can also shift as one moves from the standing position to the bent over position. Maybe, maybe not. At any rate it would be good to in some way determine if the sight picture is different with regard to ocular dominance from these two positions.

My personal preference has been to continuously stare at the target while bending over. I know the perspective changes and have thought the brain developed a "better" sight picture if one watched the target while bending over. When the target is fixed in my visual field then I go into the rest of the pre-shot routine.

Now I wonder if there is any sort of shift in dominance from one position to the other. The stereotaxic figures in the article referenced shows that visual representations are variously located for the vertical plane.

With different physical locations I would expect the development of different patterns of representation.

And of course, this supports my opinion that one should watch the target as they bend over for any changes in perspective and to account for the parallax problem.

I used the Miles test while bending over and saw what appears to be slight shift in ocular dominance. I can't rule out confirmatory bias so it may or may not be true. An "n" of one is simply not sufficient. If true it implies that sighting may be different from the standing position than it is from the shooting position.

That's why in that other thread I recommended first seeing the aim while standing, then placing the back foot and then the front foot while still standing straight up, THEN FIRST bending the knees to drop down, THEN bending at the waist to get fully into the stance.

I've found this really helps to keep my dominant eye over the line.

Thanks for the thread and info, btw.

Jeff Livingston

chefjeff
11-25-2012, 06:47 AM
IS THIS HARMFUL TO ONE'S EYES?

One of those articles mentioned to "be careful" when changing eyes. I had that concern and when at my ophthalmologist's appointment last month I asked if what I was doing was harmful. The answer: "Not at all."

fwiw,

Jeff Livingston

chefjeff
11-25-2012, 06:57 AM
The Doc said he uses a prism to keep it at bay. I'm not entirely sure what that means......



It means one eye looks in a different direction than does the other.

I have that condition and have overcome it with my mind. It took my 6 months before I could control seeing double without my glasses. Driving home from league was a trip, to say the least! I had to do that self-correction before my doctor would do lasik.

He sent me to a specialist (I forget his title but his main thing is cross-eyed children...the waiting room was full of 'em) who was a ping pong player. This guy worked with me for 3 hours (!!!) and was very interested in my pool playing and told me that pool was probably one of the best exercises possible for my condition and without it, I'd quickly revert back to double vision.

He tested me over and over and confirmed that I had self-corrected so my ophthalmologist got the OK to do surgery on me. He also said that when I reach 65 or so, I'll lose the ability to overcome this and will probably need prism glasses (that I wore for 30 years before).

Get a good doctor who will listen and help you through the process.

I'm 59, btw, so my time is coming.:frown:

Jeff Livingston

sfleinen
11-25-2012, 07:09 AM
Think this adds any credibility to what Geno teaches?

In one respect, yes -- that your orientation on the shot line often forces the brain into determining the dominant eye. In other respects, no, it disproves the theory that ocular dominance is "hard-wired and there's nothing you can do about it except to submit to it all the time."

In the first respect -- of ocular dominance shifting according to the horizontal orientation -- this is well-known. Decades (if not more) known. I mean, to boil it down to basics, if there's a cup of coffee to your far right, you will prefer your right eye to look at it as you reach for it -- even as you turn your head to face the cup of coffee square-on as you're lifting it to your mouth. And vice-versa if the cup of coffee is on your far left. The horizontal plane has EVERYTHING to do with ocular dominance, and how it dynamically shifts. We don't even realize it's happening, it's so natural. Yet some will try to have you believe that if that if you were left-eye dominant and the cue of coffee is on your right, that you'll do an Exorcist and spin your head around so that the left eye is facing that cup of coffee on your right.

I do believe in "task-oriented" ocular dominance, however. For example, reading fine print close-up with the naked eyes, I'll "prefer" my left eye for that. But when trying to make things out at far distance -- such as when at the top of a hill, looking down, and trying to make out a person walking in the forest below -- although I'll use both eyes for this, I'll shift my focus and "prefer" my right eye. And when shooting a rifle or pistol (as I'd done competitively for many years), I absolutely use the right eye -- although that could've been "trained in."

However, when getting down on a pool shot, I'm 100% binocular -- cue is cutting my chin and the centerline of my face (my nose is directly over the shaft). The brain is a marvelous organ that "blends" the two eye's differing fields of vision into one cohesive "vision center."

-Sean

JoeW
11-25-2012, 07:54 AM
Looks like this could be a much more complicated topic than I thought. Banks, M.S., Ghose, T.,and Hillis, J. (2004). Relative image size, not eye position, determines eye dominance switches. http://www.sciencedirect.com/science/article/pii/S0042698903006424

Found that … “When eye position and relative image size were varied independently, there was no consistent effect of eye position. Relative image size appears to be the sole determinant of the switch.”

After thinking about all these findings I now wonder of what use is the idea of a dominant eye as a general term (this idea is expanded on in my next post). Apparently one eye dominates in visual image processing. However which eye dominates depends upon the situation. Apparently, while we have a ”preferred” way to look at the world, our need to view things stereoscopically requires a shift in eye dominance for the best picture and is partially determined by the situation. This means that exact amount of eye dominance is only of use in specific situations. Thus a basketball players preferred eye dominance is of little use because the player is constantly and rapidly moving around the court. Tennis players and basketball players probably should not intentionally use a dominant eye preference to learn to play or shoot well because their visual demands change rapidly.

I think that for pool players this shift in dominance takes on a different meaning. Unlike the aforementioned, we do shoot from a static position. The eye dominance in this situation has historically been thought to be the same. However, as the distance to the object ball changes and the size of the object on the retina changes, eye dominance can actually switch. Banks et al worked with a 40 degree off azimuth angle and distances from 23 to 90 inches. They found that eye dominance changed and even switched over these distances. This is an interesting finding for pool players as these are related to the distances we often use.

The conclusion is that eye dominance changes as a function of distance to the target because the image size changes. While it may feel comfortable to place the cue under some predetermined position relative to the eyes, the eyes will shift dominance as demanded by the retinal image.

When the player begins with the cue closer to the right eye as a part of their PSR, eye dominance will shift as needed for the size of the target viewed. In some cases (?) the opposite eye may become dominant. This means that there is more work for the brain to do because the eye is in the wrong place for this situation.

This possible shift in eye dominance can be determined by using the Miles test over at least two distances. To conduct the test a hole was punched in a 5 X 7” sheet of paper with a pencil. Two pencils we placed on a flat surface. One pencil was about four feet away. The other pencil was about 12 feet away. I sat in one chair and used the back of a second chair as an arm rest. I held the paper rested on the second chair at arms length and then sighted the pencil tips through the hole cut in the paper.

When my face was squared to the paper and I sighted both pencil tips I found that ocular dominance did not change. I am right eye dominant and both targets looked about the same.

When I turned my face at about a 40 degree angle to the paper and sighted both objects there was a shift in dominance that is generally consistent with Banks et al findings. Eye dominance did not switch but it was different.

Many more replications by other people are needed. I shoot with the cue stick centered between my eyes and the pool table visual simulation had the least amount of change when I sighted in my usual way. When I changed my face placement to favor the right eye the ocular dominance appeared to change over distance.

I cannot know if this change is do to a change in my usual way of sighting or as result of a changed perspective. More tests with different people are needed.

It would appear that however one places a cue stick under their eyes it is probably important to be consistent. Banks et al concludes that distance and the subsequent target size does has some effect on ocular dominance when there are changes in viewing angle. My N of one study supports this finding. Though I am not sure why it supports this change in ocular dominance. Is the change a function of training or more simply the way the eyes work together.

JoeW
11-25-2012, 08:19 AM
A review of the research literature leads to the conclusion that eye dominance changes and may even switch as a function of the demands in the visual field. Angle off azimuth, distance, and lateral shifts all effect the amount of eye dominance in any given situation. While we have a preferred eye dominance the amount of eye dominance changes and may switch under some circumstances.

In general eye dominance is usually thought of as a static concept: A person is either left or right eyed dominant. This is probably the wrong way to think about it. Eye dominance is not a category, it is a process. Some what like “intelligence” as a concept.

Many people use the term categorically: You are intelligent or you are not intelligent. The reality of the situation is that there are many forms of intelligence and one is more or less intelligent in any given situation based on the demands of the situation, prior experience and current physiological status (you can be quite stupid when you are drunk). Intelligence and its use are a process. We turn it into a category or a concept because it has some consistency over many types of situations. This short hand way of labeling the world is of limited, but some, use. It is a way to communicate with others about a person's generalized capabilities. It has little use when we get serious about real functional ability.

I suspect that far too much has been made of eye dominance when playing pool. It is true that we each have a preferred ocular dominance and that these preferences are of use in, what now appears to be, very limited situations. Prior research indicates that eye dominance exhibits subtle shifts in as little as a few feet and a few degrees off vertical and horizontal center. Apparently, we are continually making subtle shifts in eye dominance as a function of the demands of the visual field. This shifting has been shown to be a dramatic shift to the point that the other eye becomes dominant under some circumstances.

I think that current practices with the cue stick more or less under one eye are nothing more than a bench mark from which the brain compensates as needed. If this is true, and the literature supports this position, then the best place to start is where the brain begins to function for aiming. This place may or may not be some point relative to one or another eye for the stereoscopic vision required to play pool.

Eye dominance is not a static concept it is a process that we choose to categorize for convenience.

sfleinen
11-25-2012, 08:34 AM
A review of the research literature leads to the conclusion that eye dominance changes and may even switch as a function of the demands in the visual field. Angle off azimuth, distance, and lateral shifts all effect the amount of eye dominance in any given situation. While we have a preferred eye dominance the amount of eye dominance changes and may switch under some circumstances.

In general eye dominance is usually thought of as a static concept: A person is either left or right eyed dominant. This is probably the wrong way to think about it. Eye dominance is not a category, it is a process. Some what like “intelligence” as a concept.

Many people use the term categorically: You are intelligent or you are not intelligent. The reality of the situation is that there are many forms of intelligence and one is more or less intelligent in any given situation based on the demands of the situation, prior experience and current physiological status (you can be quite stupid when you are drunk). Intelligence and its use are a process. We turn it into a category or a concept because it has some consistency over many types of situations. This short hand way of labeling the world is of limited, but some, use. It is a way to communicate with others about a person's generalized capabilities. It has little use when we get serious about real functional ability.

I suspect that far too much has been made of eye dominance when playing pool. It is true that we each have a preferred ocular dominance and that these preferences are of use in, what now appears to be, very limited situations. Prior research indicates that eye dominance exhibits subtle shifts in as little as a few feet and a few degrees off vertical and horizontal center. Apparently, we are continually making subtle shifts in eye dominance as a function of the demands of the visual field. This shifting has been shown to be a dramatic shift to the point that the other eye becomes dominant under some circumstances.

I think that current practices with the cue stick more or less under one eye are nothing more than a bench mark from which the brain compensates as needed. If this is true, and the literature supports this position, then the best place to start is where the brain begins to function for aiming. This place may or may not be some point relative to one or another eye for the stereoscopic vision required to play pool.

Eye dominance is not a static concept it is a process that we choose to categorize for convenience.

Thanks for this thread, Joe! And I agree; ocular dominance is a PROCESS, and not a "state." I'd been saying this all along.

Very interesting reading -- thanks for the links!
-Sean

JoeW
11-25-2012, 12:03 PM
It would appear that eye dominance is a process that shifts based on demands in the visual field. Distance, lateral shift and head position among other things all contribute to a continuing shift in eye dominance.

One of the finding that should be of most interest to pool players is the idea that eye dominance shifts over distance to the target and the concomitant change in the size of the target on the retina. This means that eye dominance changes as one moves their eyes from the target on the cue ball to the target on the object ball.

A player might have the cue stick 1/2” off the center of their face when looking at the cue ball and need the cue stick to be 1/4” off the center of their face when looking at a length of table shot. These different needs for eye dominance can contribute to a lack of consistency. Obviously the player does not move their face when they change their gaze from cue ball to object ball. What must occur is the brain makes the necessary eye dominance adjustments for change in retinal size based on distance. A close reading of the research literature suggests that this must be the case because there is a shift in eye dominance.

Given this state of affairs there should be one reference point or line of aim from which the brain makes its adjustments. Hand eye coordination and fixation on the object ball target are the two primary goals. The relationship of the cue stick to the head should be the primary concept initially addressed by the player. When this has been established the object ball is sighted relative to this position and the brain adjusts the visual field as needed for the distance to the shot.

The body functions from the mid-line as needed. That is we walk, swing a bat and reach for an object based on the center line of the body and the relative location of other body parts. While one may have an eye dominance preference with regard to any single object this preference is also relative to the head's mid-line and to the objects in the field.

The player should develop a shooting stance based on stroking the cue stick through the center of the ball with the eyes centered on the cue ball one inch (or less) in front of the player's cue stick. This should be done with the cue stick directly under the center of the face along a plane that runs through the back of the head. The chin or the nose should be used to create this alignment. Emphasis should be placed on striking the cue ball from this position and driving the cue ball straight ahead bouncing off a rail and returning to the cue tip. In this way the player knows the cue and head are in perfect alignment for striking the cue ball.

The next step in the process is to sight the object ball. Eye dominance will change as a function of distance (retinal image size) and the brain will accommodate from the standard position. The brain will make the necessary adjustments for the amount of information it uses from each eye for alignment with a target at a distance. The brain does this in any case so it is better to use the mid-line of the head as the reference point. A review of the literature indicates that eye dominance can reverse over distance and this reversal is best accomplished using the head's natural reference point – the mid-line.

The possible (even probable) shifts in eye dominance reinforce the notion that the player should study the distant target for a period of time to allow the brain to make the necessary accommodations thus reinforcing the notion of the Quiet Eye. It could well be that the need for a quiet eye is based on the shifting eye dominance. Quiet Eye research leads to the idea that a two second wait time is sufficient.

The “radical” idea suggested here is that players should set up a shot by centering the eyes and the head over the cue stick with initial focus on the object ball. The eyes centered on the cue stick is the reference point for all types of aiming.

Here is an example based on fictitious numbers.

If the eyes are centered on the cue stick and the distant target requires a two inch shift in dominance then the brain makes a one inch offset in near dominance to strike the target.

If the right eye is over the cue stick and a two inch shift is needed for a distant target then the brain may have to shift near dominance and subsequent focus by two inches in one direction and -1 inch in the other direction.

Obviously people can and do play with different head alignments. The brain compensates as needed. What is suggested here is a more symmetrical approach that takes into consideration things that are now known about how the eyes function. It may explain why some people have more difficulty consistently making left or right cut shots over a distance.

FranCrimi
11-26-2012, 07:07 AM
It would appear that eye dominance is a process that shifts based on demands in the visual field. Distance, lateral shift and head position among other things all contribute to a continuing shift in eye dominance.

One of the finding that should be of most interest to pool players is the idea that eye dominance shifts over distance to the target and the concomitant change in the size of the target on the retina. This means that eye dominance changes as one moves their eyes from the target on the cue ball to the target on the object ball.

A player might have the cue stick 1/2” off the center of their face when looking at the cue ball and need the cue stick to be 1/4” off the center of their face when looking at a length of table shot. These different needs for eye dominance can contribute to a lack of consistency. Obviously the player does not move their face when they change their gaze from cue ball to object ball. What must occur is the brain makes the necessary eye dominance adjustments for change in retinal size based on distance. A close reading of the research literature suggests that this must be the case because there is a shift in eye dominance.

Given this state of affairs there should be one reference point or line of aim from which the brain makes its adjustments. Hand eye coordination and fixation on the object ball target are the two primary goals. The relationship of the cue stick to the head should be the primary concept initially addressed by the player. When this has been established the object ball is sighted relative to this position and the brain adjusts the visual field as needed for the distance to the shot.

The body functions from the mid-line as needed. That is we walk, swing a bat and reach for an object based on the center line of the body and the relative location of other body parts. While one may have an eye dominance preference with regard to any single object this preference is also relative to the head's mid-line and to the objects in the field.

The player should develop a shooting stance based on stroking the cue stick through the center of the ball with the eyes centered on the cue ball one inch (or less) in front of the player's cue stick. This should be done with the cue stick directly under the center of the face along a plane that runs through the back of the head. The chin or the nose should be used to create this alignment. Emphasis should be placed on striking the cue ball from this position and driving the cue ball straight ahead bouncing off a rail and returning to the cue tip. In this way the player knows the cue and head are in perfect alignment for striking the cue ball.

The next step in the process is to sight the object ball. Eye dominance will change as a function of distance (retinal image size) and the brain will accommodate from the standard position. The brain will make the necessary adjustments for the amount of information it uses from each eye for alignment with a target at a distance. The brain does this in any case so it is better to use the mid-line of the head as the reference point. A review of the literature indicates that eye dominance can reverse over distance and this reversal is best accomplished using the head's natural reference point – the mid-line.

The possible (even probable) shifts in eye dominance reinforce the notion that the player should study the distant target for a period of time to allow the brain to make the necessary accommodations thus reinforcing the notion of the Quiet Eye. It could well be that the need for a quiet eye is based on the shifting eye dominance. Quiet Eye research leads to the idea that a two second wait time is sufficient.

The “radical” idea suggested here is that players should set up a shot by centering the eyes and the head over the cue stick with initial focus on the cue tip/cue ball for initial setup. The brain will then accommodate to changes in eye dominance as needed for a particular shot. This should be the reference point for all types of aiming.

Here is an example based on fictitious numbers.

If the eyes are centered on the cue stick and the distant target requires a two inch shift in dominance then the brain makes a one inch offset to strike the target.

If the right eye is over the cue stick and a two inch shift is needed for a distant target then the brain may have to shift dominance and subsequent focus by two inches in one direction and -1 inch in the other direction.

Obviously people can and do play with different head alignments. The brain compensates as needed. What is suggested here is a more symmetrical approach that takes into consideration things that are now known about how the eyes function. It may explain why some people have more difficulty consistently making left or right cut shots over a distance.

So are you saying that people should ignore how they think they see and should just center the cue under their chin, and then trust that their brains will take care of the rest?

JoeW
11-26-2012, 07:21 AM
So are you saying that people should ignore how they think they see and should just center the cue under their chin, and then trust that their brains will take care of the rest?

The literature leads to the conclusion that people do not see what they think they see at different distances. The offsets used at one distance are not the same offsets that are used at other distances. Apparently the brain shifts its relative reliance on each eye at different distances.

After thinking about it last night it occurred to me that one should learn to place the cue under the chin as a learned reference point that is part of the PSR but the initial attention should be on the distant object ball when bending over. One is a learned motor control reference point the other changes as a function of distance (actually the size of the retinal image given that the size of the target on the object ball does not change).

FranCrimi
11-26-2012, 07:24 AM
The literature leads to the conclusion that people do not see what they think they see at different distances. The offsets used at one distance are not the same offsets that are used at other distances. Apparently the brain shifts its reliance on each eye at different distances.

I just want to make sure I understand what your recommendation is. Are you recommending that people ignore what they think they see and center the cue under their chin and trust that their brain will make the necessary adjustments?

FranCrimi
11-26-2012, 07:39 AM
The literature leads to the conclusion that people do not see what they think they see at different distances. The offsets used at one distance are not the same offsets that are used at other distances. Apparently the brain shifts its relative reliance on each eye at different distances.

After thinking about it last night it occurred to me that one should learn to place the cue under the chin as a learned reference point that is part of the PSR but the initial attention should be on the distant object ball when bending over. One is a learned motor control reference point the other changes as a function of distance (actually the size of the retinal image given that the size of the target on the object ball does not change).

OK, Joe, I just read your edited post. Here's an idea to consider: Studies also show that a dominant eye will tend to present the person with a distorted sense of their body position relative to the item they are viewing. That would make more sense to me why players miss certain angle shots more frequently than other angles. I've often had to adjust a player's alignment in those instances. It wasn't that they couldn't see the shot correctly. It was that they had a false sense of where their body was positioned in relation to the line of the shot.

A simple alignment adjustment usually was all that was needed. They didn't need to re-perceive how they viewed a shot.

JoeW
11-26-2012, 07:51 AM
This is not what I am recommending. When the player sets up with an eye offset that is needed to see the cue ball three feet away this offset is not the same offset that is needed to see an object ball that is six feet away or an object ball that is ten feet from the eyes. If the player sets up for the cue ball then the eyes will have to shift their relative reliance on each eye at the distance required for the object ball.

Given that this does happen, and you can verify it by using the miles test over different distances, it is suggested that it is better to have a zero reference point at the mid-line of the head. When the eye automatically adjusts for the different distances the shifts in ocular dominance will be minimal.

I suppose the alternative would be to determine the eye offset at the center of the table and then use this offset as a standard for setting up in the PSR.

Incidentally, it is not a matter of “letting” the brain make these adjustments. The prior findings indicate that the eyes “will” make these adjustments because this is how they work.

JoeW
11-26-2012, 07:54 AM
OK, Joe, I just read your edited post. Here's an idea to consider: Studies also show that a dominant eye will tend to present the person with a distorted sense of their body position relative to the item they are viewing. That would make more sense to me why players miss certain angle shots more frequently than other angles. I've often had to adjust a player's alignment in those instances. It wasn't that they couldn't see the shot correctly. It was that they had a false sense of where their body was positioned in relation to the line of the shot.

A simple alignment adjustment usually was all that was needed. They didn't need to re-perceive how they viewed a shot.

Had not thought of that. Now I will have to re-think all these finding again. I think one of the missing pieces here is proprioceptive feed back, knowing where one's body is in space and relative to other objects. It could well be that one or another reference point is better for different people. Hmmm

JoeW
11-26-2012, 07:59 AM
In experimental psychology there is an area of study known as Field Dependence / Independence. It has been found that some people are more dependent on the surrounding field of an object while others determine their location based on their body. There are many correlates of a person's tendency to be field dependent / independent. I would not be surprised to learn that field dependence effects the way one sights a pool shot.

I know that you are not impressed by Wikipedia but here is a place to start.
http://en.wikipedia.org/wiki/Field_dependence

Here is a study that leads to the idea that field independent people are more likely to engage in sports.

http://srufaculty.sru.edu/wenhao.liu/Publication_files/FDI%20and%20PA%20by%20College%20Students.pdf

It could be that field dependent people have more difficulty sighting given shifts in dominance over distance.

Ratta
11-26-2012, 08:42 AM
OK, Joe, I just read your edited post. Here's an idea to consider: Studies also show that a dominant eye will tend to present the person with a distorted sense of their body position relative to the item they are viewing. That would make more sense to me why players miss certain angle shots more frequently than other angles. I've often had to adjust a player's alignment in those instances. It wasn't that they couldn't see the shot correctly. It was that they had a false sense of where their body was positioned in relation to the line of the shot.

A simple alignment adjustment usually was all that was needed. They didn't need to re-perceive how they viewed a shot.


That s in my opinion and from my expirience absolutley right Fran!
Til now i had *Just* 2 players who had a real problem with their dominant eye and caused of this, a completly wrong alignment- on these 2 guys everything was off, what you could imagine to be perhaps off *the striking line*, lmao!

After showing it to these guys on video, they were shocked- they thought they would be dead center on the cueball for example, too :p

Worked with both then just on alignment and drills to *find* their vision center and how to get the cue into the right position. Was a real hard work-but finally it ended satisfying for all.
Also here i just worked with the method nowadays the the sight-right method shows.

lg
Ingo

FranCrimi
11-26-2012, 08:57 AM
In experimental psychology there is an area of study known as Field Dependence / Independence. It has been found that some people are more dependent on the surrounding field of an object while others determine their location based on their body. There are many correlates of a person's tendency to be field dependent / independent. I would not be surprised to learn that field dependence effects the way one sights a pool shot.

I know that you are not impressed by Wikipedia but here is a place to start.
http://en.wikipedia.org/wiki/Field_dependence

Here is a study that leads to the idea that field independent people are more likely to engage in sports.

http://srufaculty.sru.edu/wenhao.liu/Publication_files/FDI%20and%20PA%20by%20College%20Students.pdf

It could be that field dependent people have more difficulty sighting given shifts in dominance over distance.

Thanks, I'll check out those studies. Another thing I was thinking of was the issue of sensory dominance vs. physical dominance. While sensory dominance can change eye dominance, I seriously question the permanence of it. I believe that the physically dominant eye will eventually try to take back control. Many players claim to struggle with this issue, where for whatever reason, the sensory dominance has kicked in (perhaps to a particular cue placement) and the physically dominant eye is fighting to regain control.

I also think that it makes sense that the physical eye dominance can decrease with age as some or many of those neuron-pathways that helped define the physical dominance can deteriorate.

But I think that in absence of that deterioration process and any pathologies, we're still looking at a physical dominant eye that wants to take over, regardless of any sensory dominance that may be in place at the time.

I think that's why it makes this so confusing where results from certain studies are often mixed.

JoeW
11-26-2012, 09:19 AM
Thanks, I'll check out those studies. Another thing I was thinking of was the issue of sensory dominance vs. physical dominance. While sensory dominance can change eye dominance, I seriously question the permanence of it. I believe that the physically dominant eye will eventually try to take back control. Many players claim to struggle with this issue, where for whatever reason, the sensory dominance has kicked in (perhaps to a particular cue placement) and the physically dominant eye is fighting to regain control.

I also think that it makes sense that the physical eye dominance can decrease with age as some or many of those neuron-pathways that helped define the physical dominance can deteriorate.

But I think that in absence of that deterioration process and any pathologies, we're still looking at a physical dominant eye that wants to take over, regardless of any sensory dominance that may be in place at the time.

I think that's why it makes this so confusing where results from certain studies are often mixed.

Good point. I did not find any studies that controlled for the differential visual acuity and characteristics of the field. It could well be that visual acuity differences could be the reference point for those with a physical disparity.

FranCrimi
11-26-2012, 09:34 AM
That s in my opinion and from my expirience absolutley right Fran!
Til now i had *Just* 2 players who had a real problem with their dominant eye and caused of this, a completly wrong alignment- on these 2 guys everything was off, what you could imagine to be perhaps off *the striking line*, lmao!

After showing it to these guys on video, they were shocked- they thought they would be dead center on the cueball for example, too :p

Worked with both then just on alignment and drills to *find* their vision center and how to get the cue into the right position. Was a real hard work-but finally it ended satisfying for all.
Also here i just worked with the method nowadays the the sight-right method shows.

lg
Ingo

Yes, we try to do the best we can to help our students. Once we get them corrected, then we have to help them to focus on how it feels to stand that way, so they can find it by feel. It's hard work.

JoeW
11-26-2012, 10:50 AM
Fran I found this study that might interest you. Apparently in a well controlled study sensory dominance is not a significant issue in normal vision.

Suttle, C. et al (2009). Sensory ocular dominance based on
resolution acuity, contrast sensitivity and
alignment sensitivity. http://onlinelibrary.wiley.com/doi/10.1111/j.1444-0938.2008.00312.x/pdf

From the conclusions
“Taken together, the present and previous work suggest that ocular dominance may be significant in some conditions but that sensory dominance measured by threshold difference is not significant in observers with normal visual function.”

FranCrimi
11-26-2012, 01:02 PM
Fran I found this study that might interest you. Apparently in a well controlled study sensory dominance is not a significant issue in normal vision.

Suttle, C. et al (2009). Sensory ocular dominance based on
resolution acuity, contrast sensitivity and
alignment sensitivity. http://onlinelibrary.wiley.com/doi/10.1111/j.1444-0938.2008.00312.x/pdf

From the conclusions
“Taken together, the present and previous work suggest that ocular dominance may be significant in some conditions but that sensory dominance measured by threshold difference is not significant in observers with normal visual function.”

One phrase that jumped out at me was:

"This difference between near and distance
testing may be related to the fact that
physiological diplopia is more apparent at
near than at distance, so ocular dominance
may be more related to near than to
distant vision."

That could explain players lining up their dominant eye to the cue ball in their shooting stance.

Also, this study wasn't geared toward examining ocular dominance, so they really couldn't draw any conclusions in that regard.

Okie
11-26-2012, 01:52 PM
Great discussion!

Thank you for the thread, Joe.

Ken