Rethinking vision training in sport using visual-perceptual principles to maximise performance

An innately familiar function of our eyes is that of our vision; the window into the world around us, constantly tracking, interpreting and shifting our attention to possibly important stimuli. Vision gives a sense of meaning to sounds, smells, textures, objects – our environment – that no other sense comes close to establishing.

The functional eye anatomy that allows us to perceive the world around us.

To achieve such a feat, the human visual system which consists of the eyes, the anatomy which holds them and moves them, the neural tracts and the processing regions in the brain, are a complex and interrelated web in a constant flux of perception-action coupling.

Whilst the anatomy and neurophysiology of the eye is complex and its scope beyond the detail of this article, I will briefly cover what I feel are the key parts that related to vision and human performance.

Optometrists, stop reading now.

The cornea sits in the anterior portion of the eye and focuses 75% of the light entering via specially arranged collagen fibrils. The iris gives the eye its colour and blocks excess light by controlling the aperture (pupil diameter) through the sphincter and dilator muscles (Van de Pol et al., 2000). The photoreceptor cells sit in the second to last layer of the retina which is situated at the back of the eye; the rods and cones are specialised photon-receptor cells and are responsible for our peripheral vision and vision under low lighting or colour perception and acuity respectively (Van de Pol et al., 2000).

From the photon receptor cells, the neural signal is sent via the thalamus to the visual cortex in the occipital lobe of the brain.

How attention and visual processing work in tandem to change the way we see our world

There are two sources of visual-attentive input: top down and bottom-up mechanisms.

Top down refers to allocation of attention derived from things like knowledge, expectations and agent goals whereas bottom-up mechanisms pertain to visual selection based on image properties like colour, shape etc and features are said to “pop out”.

Attention modulation of vision occurs in the visual cortex, posterior parietal cortex, lateral intraparietal cortex and inferior temporal cortex. Research has shown that the prefrontal cortex houses an area called the frontal eye field where a map of all stimuli in the entire field of visual eye movements is tagged for behavioural relevance. The brain then creates a salience map – topographic maps are created for coding image dimensions and those with stand out features persist with future map refinements until a master salience map is achieved. This is repeated with every new target.

Building on our top down, bottom-up influences, the way attention is directed toward target stimuli is said to occur in two ways: voluntary goal directed or involuntary (stimuli-driven) manner (Duc et al., 2008). The former involves intention selection of a target by the agent, the latter is when specific properties of the environment determine what is selected regardless of goals (Duc et al., 2008).

The style of attentional direction matters because of the (often) wicked learning environment of many sports our athletes play – unless they play chess…

Borrowing from a phrase coined by Daniel Kahneman (Kahneman et al., 2011) sport will have varying degrees of wicked or kind learning environments to them. In the wicked one, it is difficult to learn from experience as feedback is delayed, inaccurate or absent and rules can change without warning and there are minimal or no recurring patterns.

Much of professional sports, most notably team sports including hockey, rugby, football, combat sports or extreme sports are complex adaptive systems both about the players themselves and the structure that makes up the game. Both the agent and the system is adaptive; every move, punch, evade-and-attack, skill x,y… that is made by an agent gives them an element of feedback but also their teammates and opponent’s. This then causes all other agents to adapt their play second-by-second, minute-by-minute and this continues for the whole allotted time.  Thus, feedback is often inaccurate from a feedforward sense and patterns are constantly changing.

The athlete knows what success in their sport looks like and the fundamental principles that enable success e.g. score more goals than the opposing team by evading their players to get the ball into the goal; but the second-by-second aspects are unknowns and the affordances for action arise based on the culmination of interaction between the task, environmental and agent constraints (see previous article on dynamic systems theory) (Newell et al., 1989). The agent who has better visual acuity, contrast sensitivity and depth perception coupled with reduced time for visual-perceptual decision making has fewer constraints thus their affordances for action are going to be greater than the other agent who does not have the visual advantage! Already discussed in previous articles here, greater affordances for action likely yields superior performance in the long run as a greater repertoire of movement variability allows for more options during in-game performance.

Figure 1. Shows the top down and bottom up influences on visual-perception-action coupling depending on the sport or activity. The fundamental principles for success in top down influences are the derivative of expectations, prior knowledge and goals and these are considered a priori as the athlete knows them in advance. The bottom up influences are unknown until the point they emerge in the context of movement. Task (T): Ta might be a tennis serve onto your backhand, Tb might be a serve onto your forehand. Environmental (E): Ea could be playing into the suns glare, Eb might be playing into a headwind. Other (O) refers to the context-specific characteristics of other people e.g. opponents or team mates. Organism (OO) refers to the unknown constraints of the athlete e.g OOa prior right leg ACL graft surgery; OOb limited dynamic stereopsis in left eye from congenital defect at birth.

There are three major approaches to vision training often cited in the literature.

Lockhead et al., (2024) categorise three types of SVT in their review as follows:

·       Oculomotor techniques involve drills targeting saccades, smooth pursuit and vergence

·       Occlusion training involves temporary obstruction of part of visual scene to train visual capacity to perform with incomplete date

·       Multiple objects tracking involves and track multiple simultaneous objects across field of view whilst often performing dual tasks

The authors summarised that occlusion training appeared to be the method that most often transferred to on-field performance in sport, which shouldn’t come as a surprise given the approach involves drills and movements that are components of the sport itself aka it follows the S.A.I.D principle!!

Let’s delve into the way in which we can ensure that our best laid efforts for vision training do not go to waste.

We can use the modified perceptual framework developed by Hadlow et al., (2018) as a tool to help guide how we piece together sports vision training effectively, and it starts with understanding the three overarching principles for successful transfer to sport.

1.       The target skill should discriminate between athletes of different skills ie. what are the performance limiters that elite athletes learn to work around or develop that contribute to their performance

2.       Improvements in the skill of interest should be possible through training

3.       Any improvement in skill should transfer to on field performance

For skill practice to be most effective, tasks should accurately recreate sources of performance-relevant information that athletes perceive and use to support movement coordination. This might be the use of opponents, implements like racquets or balls, and of course correspondence in visual stimuli.

Only by coupling high fidelity information with a physical response (perception-action coupling), we stand the best chance of having transfer from the athlete’s skill performance in training to competition.

The spider chart in Figure 1 below nicely illustrates how I find laying out the perceptual framework in a practical and useful manner for vision training. It provides a visual representation for what aspect of the visual-perceptual framework I start with and whether it could be considered near or far transfer (Renshaw et al., 2022). The goal of all rehabilitation, but most importantly the return to sport stage onward, is to end up with the athlete performing activities and drills resembling phase 4 in the figure. At this stage we know we would be fulfilling the 4 principles for maximising dynamic correspondence laid out by Renshaw et al., (2022) and would have the greatest dynamic correspondence to their on-field performance.

Figure 1. Shows a the modified visual-perceptual framework for progressing sports vision training from far to near-skill activities in line with the framework by Hadlow et al., (2018)

The useful thing about the visualisation of the framework in a spider chart is that we can see how even early in the rehabilitation phase, we can still work in to high levels of near transfer in say targeted visual skill and training stimulus using a vicarious experience of another player via video or observing team mates in person but the primary response might be a generic one, like the athlete has to verbally express what the player (in the video) might do in a certain situation. This allows us to work around tissue healing or organismal constraints that may be imposed in the earlier stages of rehabilitation following injury or surgery.

An easy example for why progressing from phase 0 to 4 in the way suggested above makes sense. Say you are at the beach, and you have got your metal detector with you. You forgot to set the frequency of the detector to be able to pick up gold and silver (incorrect stimulus) – you’ve been told this beach has a trove of gold and silver coins somewhere from a previous smuggler’s mishap! What’s more, you have never used a metal detector before, so you don’t know you are meant to held it roughly 15cm from the sand and closer when you get a bleep (poor skill acquisition). When you start digging (primary response) you are coming up empty every time because you are unable to “pick-up” on the right stimuli in the environment (the sand) and lack the skill with the detector to figure out the right spot to dig. So, it makes sense then to establish the capacity to both pick up on relevant stimuli and have the visual-perceptual skill to pick up on appropriate stimuli when they are present, before developing movement fidelity (more on this term below!).

I would be reticent to suggest that we break the stimulus, response and visual-perceptual skill down into drills; instead, we should view them as a continuum moving from far (middle of the spider diagram) to near (edges of spider diagram) skill transfer. Again, if we revisit my previous article here on dynamic systems theory and the paper by Renshaw et al., (2022) then we accept that human movement is a self-organising phenomenon of affordances for action in response to task, environmental and organismal constraints and thus near practise tasks are considered to emulate the observed interactions of the individual and the environment to those seen in the performance setting.

When this occurs, there is high fidelity of performance; as suggested by Renshaw et al., (2022) fidelity exists when there is a transfer of performance from the ‘simulator’ (i.e. practice) to the ‘simulated’ system (i.e. performance). Leading from this, skill is a process-orientated phenomenon that emerges as the individual improves their fit between themselves and their environment in pursuit of a goal-oriented action. Eminent researchers in the field of ecological dynamics in sport have proposed a three-stage mode of skill development from a dynamic systems perspective that we will apply to our visual-perceptual framework.

Adapted from Button et al., (2020) (as cited in Renshaw et al., 2022) stage one focuses on developing coherence between task stimulus and targeted visual skill; by exposing the athlete to far-skill activities for basic visual skills and training stimuli they can begin to learn to pick up visual cues from the environment that are fit-for-purpose i.e. successful outcome of the task at hand. Progression into stage 2 shifts the focus on becoming perceptually attuned to environmental stimuli; we shift to near-skill activities where the training stimuli and visual anticipation and decision-making take centre stage. Here the focus is on fine-tuning their attention to pick up perceptually relevant information from the environment that expands their affordances for action.

Remember, the athlete with the greater affordances for action, all other factors equal, is going to be more likely to succeed! Again, stage two should expand, not shrink, the number of contexts the athlete performs near-skill activities in as we are looking to increase their affordances for action in all contexts for their performing activity. Revisiting the prior article on attractor states; we can train certain attributes for an attractor state in the hope it deepens the well but there is still no guarantee that movement will gravitate towards that state, so we must balance depth of the single AS with breadth of all possible attractor states.

The penultimate stage sees the expansion from far- to near-skill activities in the primary response aspect of the visual-perceptual framework in Figure 1. In my mind, the development of this stage last makes sense. Why? Well, our visual-perceptual capacity is what allows us pick up the right cues from our environment and gives us the affordances for action, the action (i.e. human movement) is what then allows us to attain the goal at hand. Any inability to pick up the relevant visual-perceptual cues will coincidently impede the success of any movement toward the intended goal as there is a greater number of unknowns at any one point in the system, which in the wicked learning environments of sport (see Kahneman et al., 2011) spells trouble! The fewer correct perceptual cues picked up, the more rigid, predictable and likely poorer fit the subsequent movement will be relative to the task.

So, phase four (see Figure 1) takes the athletes’ newly developed and (now) honed visual-perceptual skills and applies them to increasingly near-skill activities. Importantly, even though we have honed their VP skills from phase 0-3, the introduction of near-skill movement responses results in a new plethora of affordances for action and visual-perceptual tuning because of the reciprocal coupling of perception-action (movement). So, you may find yourself delving back slightly to introduce new constraints in the targeted visual skill aspect of the framework.

Hopefully the above article provides a flavour for how you can approach perceptual-action development in your athletes from rehabilitation right through to return to performance. Any comments please drop them below or further questions drop me an email!

References

Van de Pol, C. (2000). Basic anatomy and physiology of the human visual system. Helmet-Mounted Displays: Sensation, Perception and Cognition Issues. US Army Aeromedical Research Laboratory.

Duc, A. H., Bays, P., & Husain, M. (2008). Eye movements as a probe of attention. Progress in brain research, 171, 403-411.

Kahneman, D. (2011). Fast and slow thinking. Allen Lane and Penguin Books, New York.

Lochhead, L., Feng, J., Laby, D. M., & Appelbaum, L. G. (2024). Training vision in athletes to improve sports performance: A systematic review of the literature. International Review of Sport and Exercise Psychology, 1-23.

Hadlow, S. M., Panchuk, D., Mann, D. L., Portus, M. R., & Abernethy, B. (2018). Modified perceptual training in sport: a new classification framework. Journal of Science and Medicine in Sport, 21(9), 950-958.

Renshaw, I., Davids, K., O'Sullivan, M., Maloney, M. A., Crowther, R., & McCosker, C. (2022). An ecological dynamics approach to motor learning in practice: Reframing the learning and performing relationship in high performance sport. Asian Journal of Sport and Exercise Psychology, 2(1), 18-26.

Newell, K. M., Van Emmerik, R. E. A., & McDonald, P. V. (1989). Biomechanical constraints and action theory. Human Movement Science, 8(4), 403-409.