Your dominant eye sends a slightly stronger signal to your brain’s visual processing center, which means it provides the more reliable reference point for lining up a target. When you aim with your non-dominant eye instead, your brain is working with the weaker of its two visual inputs, and your point of aim shifts to one side without you realizing it. This matters most in shooting, archery, and any activity where you need to align your body, a sighting device, and a distant target along a single line.
How Eye Dominance Works in Your Brain
Even though both of your eyes are healthy and functional, they don’t carry equal weight once their signals reach your visual cortex. The nerve fibers from each eye connect to dedicated strips of brain tissue called ocular dominance columns, and these columns compete with each other to form permanent connections. The dominant eye wins more of that competition, earning a slightly larger share of neural real estate. This happens during early development, before visual experience even plays a role.
The practical result is that your brain treats one eye’s image as the primary reference and the other as supplementary. When both eyes are open, the dominant eye’s perspective quietly wins any conflict between the two images. About 71% of people are right-eye dominant, while the remainder are left-eye dominant or, in rarer cases, have no strong dominance at all.
Why It Matters for Aiming
Aiming requires you to line up three things: your eye, a sighting reference (like a front sight, scope reticle, or arrow tip), and the target. This only works if the eye doing the alignment is the one your brain trusts most. If you aim with your non-dominant eye, the image your brain prioritizes is coming from a slightly different angle, several centimeters to the side. Your shot lands off-target even though your alignment looked correct through the sight.
This isn’t about one eye being sharper or faster. Research measuring simple reaction times found virtually no difference between dominant and non-dominant eyes (about 282 milliseconds versus 278 milliseconds). The advantage isn’t speed. It’s that your dominant eye provides the spatial reference your brain defaults to when combining images into a single picture of the world. Depth perception, which relies on slight differences between what each eye sees, also depends on this weighting system working properly. Your dominant eye anchors the 3D picture your brain constructs, making it essential for judging distance to a target.
Aiming With Both Eyes Open
Keeping both eyes open while aiming has real advantages. You maintain full peripheral vision, better depth perception, and more light reaching your brain. But it only works well when the eye behind your sight is also your dominant eye. If it is, your brain naturally suppresses the competing image from your other eye, and the sight picture stays stable on the target.
If your dominant eye is on the opposite side from your aiming eye, both-eyes-open aiming becomes a problem. Your brain keeps trying to use the dominant eye’s perspective, which isn’t aligned with the sight. The result is a doubled or shifting image that makes consistent accuracy nearly impossible. People who are “same-side dominant,” meaning their dominant hand and dominant eye are on the same side, have a much easier time shooting with both eyes open.
How to Find Your Dominant Eye
The most common method is the Miles test. Extend both arms in front of you, palms facing away, and overlap your hands to create a small triangular opening between your thumbs and index fingers. With both eyes open, center a small object about 15 to 20 feet away inside that opening. Now close one eye at a time. When you close your dominant eye, the object will jump out of the opening or disappear. When you close your non-dominant eye, the object stays put. The eye that keeps the object centered is your dominant eye.
A simpler version is the Porta test: extend one arm and align your thumb with a distant object while both eyes are open. Alternate closing each eye. The eye that keeps your thumb aligned with the object is dominant. These tests take seconds and are reliable enough for practical use, though it’s worth noting that dominance can sometimes be weak or inconsistent. In one study, the sighting test and a sensory-based test agreed on which eye was dominant only 50% of the time, suggesting that some people don’t have a strongly dominant eye at all.
What to Do if You’re Cross-Dominant
Cross-dominance means your dominant eye and dominant hand are on opposite sides. If you’re right-handed but left-eye dominant (or the reverse), you have a few proven options rather than fighting your biology.
- Close your non-aiming eye. The simplest fix. If you’re right-handed and left-eye dominant, closing your left eye forces your right eye to take over for alignment. This works well but reduces peripheral vision and can cause facial tension over long sessions.
- Use an eye patch or blinder. An opaque patch over your dominant eye blocks its view of the sight picture while keeping the eye physically open. This eliminates the squinting effort and reduces muscle fatigue. Some archers and competitive shooters attach a small blinder to their hat brim, positioned so it blocks only the sight picture while preserving peripheral vision and light.
- Switch shooting sides. Some instructors recommend learning to shoot from your dominant-eye side instead of your dominant-hand side. Eye dominance matters more than hand dominance for aiming accuracy, and many people adapt to the hand switch faster than expected.
- Use a hybrid approach. Start with both eyes open for maximum awareness, briefly squint your non-dominant eye to verify alignment on the target, then reopen both eyes before completing the shot. This gives you the spatial benefits of binocular vision for most of the process while using a quick check to ensure your dominant eye isn’t pulling your aim off-line.
The best method depends on your sport and personal comfort. Competitive archers tend to favor blinders because they allow long practice sessions without fatigue. Recreational shooters often start with the simple eye-closure method and experiment from there. The key insight is the same across all of these: your brain will default to your dominant eye’s perspective whether you want it to or not, so your aiming system needs to account for that rather than ignore it.