A Practical Example

Changes in dominance: Clay Pigeon Shooting

When eye dominance changes from one eye to the other, errors occur in the accuracy of visual direction. These errors can arise when the eyes change their focus from one fixation point to another, or when the fixation point is moving. In such situations nearer targets can be observed to in different visual directions.

This phenomenon occurs in everyday life, albeit frequently unnoticed, but in the art of clay-shooting the problem of changing dominance has been well documented by Pete Blakeley. Since 1998, Pete Blakeley has been the shooting coach at one of the most prestigious gun clubs in the world, the Dallas Gun Club in Lewisville, Texas. His 2003 book, “Successful Shotgunning”, is considered the most elaborate and definitive guide to ‘shotgunning’ ever written. Blakeley’s description of the main problem affecting shooters is that when a right-eye dominant person takes aim at clays coming from a particular direction, dominance switches from the right eye to the left eye, resulting in a misaligned shot. Blakeley’s solution to this problem was to close or shut off the weaker eye, just before the shot is taken, thereby ensuring that the aim of the gun was that of the dominant eye.

The problem manifested itself when the clay was coming from a certain direction. The direction he made particular reference to was a left-to-right direction of the clay, for a right-eye dominant person. The same problem exists when the clay is coming from a right-to-left direction for a left-eye dominant person, and the reason for both is also exactly the same, when we examine the problem in the context of SSSRD. The common outcome of this is a missed shot and the shot is usually fired behind the clay target. Blakeley’s observations are completely consistent with the structure of SSSRD and the function of the cortex eye.

The barrel of the gun does change from the aim of the left eye, to the aim of the right eye, where there lies a large disparity, as illustrated by targets passing over the retinal-section boundary, VL. Pete Blakeley, in documenting this problem, unknowingly identifies this retinal boundary in a real life experience, where in specific circumstances, visual direction is compromised by a breakdown in the dominance of the dominant eye. In SSSRD, the binocular single image consists of monocular inputs from both eyes. The monocular input of the dominant eye is the single largest input area, section A, nearer than the fixation point, and it extends to the visual axis of the left eye, VL, nearer than the fixation point. It is thus the only monocular area wherein the fixation point can be accurately and directly aimed at, while at the same time, the aiming object is always on VR1, and remains in the same monocular area. This is because the visual axis of the right eye, VR1, is nearer than the fixation point, unlike VL, and is not a retinal-section boundary.

A right-eye dominant person takes for granted the accurate identification of an object by pointing directly at it, but this aspect of vision obviously evolved, like all other aspects of the visual system, over millions of years. The problem was solved by the creation of the largest retinal-section, controlled by the dominant eye. That is the identification of a selective object by simply pointing or aiming at it. We can appreciate this when we simply point a finger at a target in space, but the view of the finger by the eye that is not dominant appears to be substantially offset to the target. We can observe this phenomenon by pointing a very fine pin at another pin situated only a few millimetres away, the offset is observed in exactly the same way.

Figure 6.6: Clay pigeon shooting highlights the confusion caused by a change in dominance between the two eyes. 

Pete Blakeley’s observations are correct. What’s actually occurring is that when the clay is coming from a right-to-left direction (for a right-eye dominant person), the gun can be aimed behind the target, and then lead the target (the target being the fixation point) to make an accurate shot and still remain in the sectional view of the dominant right eye (section A1). The gun does not cross the visual axis of the left eye VL, into section B, the monocular-section of the left eye, and it always remains in section A. In figure 6.6, the shotgun is firstly aimed behind the moving target. As the shotgun crosses the visual axis of the right eye to lead the target, it remains in section A, the retinal-section of the right eye.

When the clay is coming from a left-to-right direction (the shotgun again starts behind the clay target), it is left of the visual axis VL, in section B1, and in the monocular view of the left eye. The aim of the shotgun has to lead the moving target at some time in order to make an accurate shot. Thus, in effect, the shotgun has to be aimed slightly ahead or right of the moving clay target. The moment that the gun is viewed right of the target it crosses into the monocular view of the dominant right eye, having crossed the retinal-section boundary VL, into section A. The gun instantly appears to be aiming behind the target (fixation point), so confusion arises. This usually results in a miss and the shot is usually fired behind the clay target, as mentioned previously. Therefore, the barrel of the gun changes from the aim of the left eye to the aim of the right eye, where there lies a large disparity in the visual direction of the two eyes. Directions 1 and 2 of the left eye and direction 3 of the right eye, on the right side of the previous figure, highlight this.

As illustrated with targets passing over a retinal-section boundary, no target can be aligned without first being viewed in double on VL, the visual axis of the left eye nearer than the fixation point. However, this is not so for VR1, the visual axis of the right eye nearer than the fixation point. This visual axis is not a retinal-section boundary and is incorporated into a larger retinal-section, which renders it as the dominant eye. The opposite is true for a left-eye dominant person; the visual axis VL is not a retinal-section boundary and it is incorporated into a larger retinal-section, which renders it the dominant eye.

Pete Blakeley, in documenting this problem in clay target shooting, unknowingly identifies a real-life experience where the retinal-section boundary VL - the visual axis of the left eye in the cortex eye nearer than the fixation point - is observed. The example also highlights a situation whereby the visual direction of the dominant eye is affected by the encroachment of the dominance of the weaker eye in unusual circumstances. This clearly affects the normally accurate visual direction of the dominant eye. It is also worth noting in the context of visual direction in SSSRD, those retinal-section boundaries, in particular VL, of the weaker eye, and VR1, of the dominant eye, are very important in understanding how to insure visual accuracy. It is not surprising that in clay pigeon shooting, the majority of left-eye dominant people instinctively fire off their left shoulder and the majority of right-eye dominant people instinctively fire off their right shoulder. As previously illustrated, the dominant eye controls the largest retinal-section nearer than the fixation point (section A) and enables visual direction to be stable in our visual world. The dominant right eye views the visual directions of targets in section A1. Visual direction is judged from point A to point B (the fixation point). The targets in section A1 farther than the fixation point play no role in visual direction, only in exceptional circumstances.

The directions of targets however, approaching or moving away from that retinal-section, are more accurately judged than the directions of moving targets in the other two retinal-sections in the binocular fields, B and B1. The directions of targets in these two areas are judged by the visual direction of the left eye. As aforementioned, the left eye in section B, nearer than the fixation point, can in exceptional circumstances, become the dominant eye. Section B1, like section A1 farther than the fixation point, plays no role in visual direction other than movement of targets in that retinal-section that are located in the same visual direction of the left eye.

At this point, it must be stated and clarified that contrary to conventional opinion; visual direction is not the average of the two monocular views. Visual direction has nothing to do with the image of an object that is viewed by each eye being impossible to align an image inside of Panum’s fusional area, with images outside. It has nothing to do with one of the double images taking precedence or one being ignored or suppressed. The dominant retinal-section developed with the natural evolution of the visual system.

Without a dominant eye, it would be impossible to play fast outdoor ball sports like hurling, cricket, or tennis, not to mention the difficulties that would arise in our ability to perform everyday tasks such as driving a car, or operating machinery that requires visual accuracy. As aforementioned, there is no fusion in the single image and there are no overlapping visual fields. The only small overlap that occurs is in the binocular single image and this results from the function of the cortex eye. The overlapping areas are sections of separate retinal-sections of opposite eyes, so fusion and correspondence play no part in the design and creation of the single binocular image.

The above is an excerpt from the ground-breaking book "SSSRD and the Cortex Eye" (Choice Publishing, 1st edition 2009)