Depth perception is the ability to perceive
the world in three dimensions.
How you see distance may not accurately reflect reality. Test yourself by tossing a coin to a nearby target. Do you consistently come up short or overshoot the target?
It is especially the ability to judge the distance between objects in visual space.
It is important to realise that your eyesight and your vision are not the same thing.
Vision is more than just visual acuity; that is the ability to see letters on an eye chart.
Vision entails the ability to make sense of what you are seeing so that you can act on it. The fact that you can see something does not necessarily mean that your brain is getting accurate information from your eyes.
According to Dr Steve Kaluzne and Dr Tony Piparo in their training manual Master the Art and Science of Putting depth perception is important on distances closer than about 20 feet. Other peripheral visual clues such as the horizon, trees, and hills are used to determine distance at distances greater than 20 feet.
How you see things may not accurately reflect reality. For example, you may judge the distance between your ball and the hole at 12 feet when the actual distance is closer to 16 feet.
If you visually constrict space, your putts will tend always to be short. On the other hand if you visually expand space, your putts will tend to go long.
Putting, therefore, is not just about stroke mechanics and technique. Your vision and how you interpret distance play a vital role in seeing slopes on the green, aligning your putterface accurately to your target, and deciding how hard to hit the ball.
For example, if you see the distance wrongly, working on your setup and stroke may do little to improve your distance control.
Unlike eyesight that you receive at birth, you have to learn your visuals skills. However, it pays to understand a little about how your eyes team together to perceive distance.
Many people have some degree of eye muscle imbalance, either tending towards esophoria, (seeing objects in space closer than they are) or exophoria (seeing objects in space farther away than they are).
So if you are consistently short on your long putts, one of the reasons could be an eye imbalance. Dr Craig Farnsworth in his book See It & Sink It refers to this spatial error as Z-axis misperceptions.
For example, given a self-test to toss a coin to a nearby target with your eyes closed (after first evaluating the distance) does your coin come up short or overshoot the target?
Professional golfers whose livelihood depends on their ability to avoid three-putting often seek out a Sports Vision optometrist in order to have their own unique visual system assessed. For the weekend or casual golfer going to such length may be overkill.
The way you see reality when it comes to judging distance will depend on your quality of your depth perception.
Keeping a record of how often you are short and long on your distance putts may help you to determine how well your eyes are seeing distance.
1 = www.eyechartmaker.com
2 = Illustration Dr Craig L. Farnsworth 'See I & Sink It'