"Eye Dominance" is not the eye that's the "strongest" or has the best vision but refers to the eye that the brain "prefers" or the one that has stronger "processing" in the brain. People usually have one eye that likes to "take over" when binocular vision is impaired, or one eye that is more sensitive to visual discrimination. My eyes are green, and sensitive to the light, but it still seems that even with sunglasses on, if I'm going to get "poked in the eye", it will be my dominant one.
For hunters and sharpshooters, it's recommended that one uses the dominant eye to line up the sights for that reason, because visual acuity, or discrimination is better, resulting in better accuracy. In shooting, in which fine monocular coordination and vision is required, the dominant eye certainly has an advantage. During suppression, when the brain "chooses" to process only one eye, the other eye is in essence "shut down". The brain is a very complex yet simple organ, in which a vast amount of visual information can be processed simultaneously or can completely disregard information from the one eye.
I'm right handed but if you watch me as I shoot I have my right eye closed. And I am right handed. Which means I am LEFT eye dominant. Or Cross dominant. Most right-handed people are right-eye dominant and most left-handed people are left-eye dominant. But this certainly isn't true for everyone. For some people, hand and eye dominance are opposite, about 15% of the total population, a good percentage of which are women. Cross dominant eye is more common in female shooters and adolescent males, so ladies, do not believe those who tell you simplistically that everyone should shoot with two eyes open. For adult men, the majority who are not cross dominant it is a skill that can be learned fairly easily, but if you are cross dominant, it's much harder. About 70% of men are same-side dominant and they can be well advised to shoot with both eyes wide open. Also, with women, as with younger boys, absolute eye dominance in either eye is not the norm. And unlike the boys, they do not generally grow out of it.
Cross domination does create some differences in participating in the shooting sports, and as it can be subject to some changes due to sex, age and stress, it's good to periodically check which is your dominant eye, it might well result in an improvement in your shooting.If you're new to shooting or want to confirm which eye is dominant, it's easy. There's more than one way to do it. (1) If you hold your hand out at arm's length and make a circle, then view an object across the room by looking through that circle, your brain must choose which eye will actually focus on the object. Since your eyes are about 3" apart, both eyes cannot maintain the direct line-of-sight to the object. So one eye must take command, and you will, without thinking about it, position your hand more to the right if you're right-eye dominant, or slightly to the left if you're left-eye-dominant.
In either case, the eye that takes over and maintains the sight-line is the dominant eye. (2) Easier yet - make a small hole in the center of your hands, bring it up to the object you are looking at . . .mmmmm. . . .HP sauce. . . . and with both eyes open, look at the object and bring your hands to your face. The eye you come closest to as it draws near is normally your master.
One other way - (3) hold a CD at arms length. If you're a right-shouldered shooter, hold the CD in your right hand. Left-shouldered shooters hold the CD in your left hand. (Ignore the hand I have selected in the photo, that was simply so I could hold the camera in my right hand). Now look through the hole and focus on a stationary object. If you are a right-shouldered shooter, close your left eye. If you are left-shouldered, close your right eye. Now does the object you're looking at through the hold in the CD vanish from view or move it's position slightly across the hole? Or does it stay in one place? If the object remains stationary, you have the correct eye dominance. If it vanishes, you have a cross "master eye" dominance. Obviously there's subtle variances and some folks have shallow or "middle" vision.
I'm cross eye dominant, not a problem with handguns, unless they are really short barrelled (a low stock may cause a shift of eye dominance on all or, more commonly, some targets -those which cause one to press their head down into the stock). With most handguns, I simply turn my head slightly prior to the draw to line up my master eye down range and thus gain just a little speed on the first shot.
In my opinion , it's a bit more of a problem with shotguns. With a rifle, accuracy depends on a rock-steady hold, as the eye slights the front and rear sights to a stationary target. Shotguns though are dynamic, they're weapons of movement, My shotgun doesn't have a rear sight and to use it, my dominant eye thus becomes the rear sight. Where my problem lies with a shotgun is that I'm a right-shouldered shooter with a dominant left eye instead of a right one. So my left eye is controlling where my gun points and I will shoot behind a left-to-right crossing shot and in front of a right-to left.
If you have cross dominance and you discover it while new to the sport you can likely learn to shoot from the same shoulder as the master eye. For a new, young shooter, this is as easy as learning any new motor skill. But for those of us who have been shooting off and on for years, it's almost impossible to change the master eye, and changing to the opposite shoulder will just feel strange as you've already got some "muscle memory". Some instructors (and I am NOT an instructor - these are just my experiences) state a solution would be to block the cross-dominating eye with an eye patch or tape on the lens of the shooting glasses, to force you to use the non-dominant eye until it becomes more comfortable. However, this will give a partial loss of binocular and peripheral vision, but some readers have recommended it.
What works for me is to close the cross-dominant eye before the shot is taken. By doing this, I've retained peripheral and stereoscopic vision by keeping both my eyes open as I evaluate the shot, until the last split-second. Now I've got a clear picture of my target/barrel relationship with no chance of cross-dominance kicking in.
Of course the shotgun, with its wide pattern, is a forgiving weapon and despite dominance, you will do well some of the time. However, it never hurts to make sure that the eye that is above the rib is the one that you rely on to give the brain the correct ocular information.
Long guns, and long guns/long range are another issue. Whether you are shooting at 100 yards, or 1000, it's a consideration.
If you are shooting a rifle right-handed, it is almost impossible to lay your head far enough over on the rifle stock to be able to sight with your left eye. Here, all you can do is force the mind to utilize the non -dominant eye (with a patch or tape on the glasses). I like the opaque tape idea, better than the patch, as this forces the non-dominant eye to take over and aim without totally blocking vision in the dominant eye. There are also sighting devices for sale but I would hesitate to recommend any one of them as I've not tried one. Talk to other shooters, more are cross- dominant than you think. Find out what works for them. Have fun experimenting, but this is a complex subject and professional guidance (and that is NOT me) can be a real help.
Barkley is, unfortunately, BOTH eye dominant when it comes to the begging look. That's not fair