Dear Kurt,
If the gaze is set straight out of the face and the golfer's head and neck are positioned square to the putter face as aimed, the usual culprit for aiming to the outside is the head swivel -- the head does not swivel on a stable axis from center of base of neck out top of head, so that the button on the cap would "scratch out from under a fingertip backwards to the right (right-hander)" during the head turn from ball down the line.
This sort of head swivel with wandering top of axis will also occur with a gaze that is directed out of the face somewhat down the cheeks instead of straight out of the face. But even if you fix the gaze, the flawed head swivel remains to plague your aim. You have to fix all together: setup, gaze, head swivel.
The easiest and cheapest way to monitor your head swivel is to form a tiny telescope with your right fist and aim it straight out of your face at your right eye so tyhe long axis of the telescope meets the plane of the face in a perpendicular fashion (ie, the gaze is "straight out of the face"). Then 1) square up to a line on the floor, 2) bend the back and neck and head as in addressing a putt until the line shows up inside the tiny hole of the fist telescope, and then 3) rotate the head so that the line REMAINS inside the tiny fist telescope throughout the head turn down the line on the floor.
This in effect converts your line of sight into a laser beam, and it's pretty cheap!
Another cheap-o way to diagnose and correct the problem is to use a card or sheet of paper and position the edge across both pupils to block looking down the cheeks and to create a visual line from pupil to pupil along the edge of the paper / card. Then when your square up to the aimed putter face, the edge-line meets the putter face flush and so matches the aim line of the putter. Then when you rotate head and paper together down the line, the edge of the paper will have to stay matching the line of the putt or else the head swivel went awry. You can test this out over a line on the floor as well, so that the edge of the paper stays matched to the line on the floor the whole time the head is turning down the line.
The third element is a square setup that positions the head-neck-eyes in relation to the aimed putter face so that the line across the skull from outside corner of eye socket to opposite outside corner of eye socket matches the line of the putt as defined by the aim of the putter face. The skull line matches the aim of the putter face, and the axis of the head and the throat line from chin to top of sternum matches the top leading edge of the putter face. With this matching setup plus a straight gaze plus a good head swivel on a spinning but otherwise stable axis of head rotation, the head turn will run the line of sight in the same straight line that the putter aims along and reveal exactly where the putter face really aims.
A cheap-o gizmo to get this setup of the head-neck-eyes correct is a pair of work goggles or throw-away glasses. Run a Sharpie line across the lenses from frame corner to frame corner. On the right lens, about 1" inside from the center of the nose piece, draw a vertical line that is perpendicular to the corner-to-corner line. Wearing these glasses, then setup to an aimed putter face so that the horizontal line appears to meet the putter face flush at the sweetspot and the vertical line (close the left eye) appears to match the leading edge of the putter face. This does not require that the eyeballs be directly above the ball -- only that the gaze direction be straight out of the face even if the eyeballs are inside the ball. Both pupils of your eyes should be looking straight thru the horizontal line and your neck should be extending perpendicularly up out of your shoulder frame.
The one thing that screws up this setting up to the aimed putter face is a neck that tilts sideways up out of the shoulder frame. the usual deal is what I have termed "ballstriker neck" in which the golfer's hours on the range hitting full shots in a modified K setup chronically casts the neck into a tilt to the side away from the target (right tilt for a right-hander). using this setup posture in addressing an aimed putter face will make you see the target to the outside. To diagnose this, stand with good erect posture and eyes closed directly facing your bathroom mirror and then open your eyes and assess whether the two pupils make a line that tilts down to the right. You may need to place a length of masking tape level across the mirror at the height of your pupils or slightly below this height before trying the eyes-closed posturing, so that there is a true reference to level waiting to greet you when you open your eyes.
If I were a betting person, diagnosing your problem without ever having seen you in person, I would bet on both the flawed head swivel and the presence of some ballstriker neck. Even if you correct the ballstriker neck, you will still have to practice the head swivel over a line on the floor.
You also have the issue of why things aimed straight objectively appear subjectively to be aimed to the inside (left for a right-hander). The lesson here is that your "normal" is wrong, so expect the "correct" to seem "wrong" until you get used to it. The sense of where the target is is NOT only about vision, but is more about body postures and motions to learn where the target is located in relation to where the ball and putter and body are located. It's not about looking down the line -- it's about moving the straight-out gaze straight down the same line the putter face aims with a good head swivel from a square starting posture. Get the posture right at setup, set the gaze straight out of the face, and swivel the head -- it's simply the geometry of body posture and movement, and not at all about vision, that accurately teaches the body where the putter face aims (or not).
Cheers!
Geoff Mangum
Putting Coach and Theorist
Geoff Mangum's
PuttingZone
PuttingZone Clinics
Flatstick Forum
PuttingZone Channel on YouTube
PuttingZone Picasweb Image Gallery
Golf's most advanced and comprehensive putting instruction -- you're either in the PuttingZone, or not.
Over 2 million visits -- 100,000 monthly from 50+ countries -- and growing strong.