Saturday, December 19, 2020

Academic Quick Hit: Ventral and Dorsal Contribution to Visual Anticipation in Fast Ball Sports - Simon Bennett, ed 2008

Where I attempt to give a quick summary and opinion on an academic paper that connects to teaching, learning, and/or sport.

Why I think this paper matters:
Information Processing and Ecological Dynamics are two separate schools of thought in motor learning and their proponents are well-entrenched in their positions. The two-stream system may well be an opportunity for each side to compromise a little in the name of more accurately describing how skilled movement happens.
"In the course of action the activity of the ventral and the dorsal systems must be synchronized in a meaningful way such that they can work together. The interaction is reciprocal in that the ventral system constrains the contributions of the dorsal system, and the dorsal system may also affect the workings of the ventral system" (p. 120).

Bennett, S. (2008). Special Issue: Ventral and dorsal contribution to visual anticipation in fast ball sports. International Journal of Sport Psychology, 39(2), 97–177.

Type of Paper: Special Issue with target article and six commentaries
Occasionally, a journal will focus on a specific topic for an entire issue and sometimes that topic is a specific article that all the other articles in the issue respond to. In this case, the target article is "Ventral and dorsal contribution to visual anticipation in fast ball sports" by John van der Kamp, Fernando Rivas, Hemke van Doorn, and Geert Savelsbergh.

Highlights (target article):
- The authors of the target article are building on the work of Milner and Goodale, who have written books and articles about the "two visual stream system". There is a great deal of neurological evidence that visual information enters our eyes and then goes in two different "directions", ventrally and dorsally, once it hits our brains. Each stream specializes in different kinds of information.
- "The ventral system is involved in perception of objects, events, and places. As the ventral system gains knowledge about what the environment offers for action, it can also contribute to action" (p. 102).
- "The dorsal system is designed to visually guide movement execution" (p.102).
- The authors' use of the term "knowledge about" is important because it contrasts with "knowledge of" the environment. They intend to show that each system is better at managing certain kinds of information. I think this is an opportunity recognize that each system needs the other in order for an athlete to perform many skills, especially in ball sports.
- The ventral system is allocentric, or world-centered, while the dorsal system is egocentric, or body-centered. These terms further reinforce the distinction between "knowledge about" and "knowledge of" the environment.
- For me, the most important part of the target article is figure 3 (p. 109) in which the authors propose that "in the course of action the ventral and dorsal systems show parallel engagement". So the two systems work alongside one another.
- The authors show that many experimental results that are intended to support the information processing point of view are likely incomplete because they only allow the implementation of the ventral system.

Highlights (Abernathy and Mann article):
- The fact that many experimental results don't engage the dorsal system has been "largely a consequence of methodological constraints rather than necessarily a strong, conscious commitment by researchers" to uphold a particular philosophical view (p. 137).
- A main difference between experts and novices is probably that the expert's dorsal system is better attuned to their environment (p. 138).
- We must be careful to recognize the difference between errors of "poor pick-up of advance information" and errors of "poor response selection strategy" (p. 140). Did two athletes see and interpret something differently or did they see the same thing but selected different solution strategies?
While there were plenty of ideas I took away from the other commentaries, I think they are more specific to my personal learning so I won't take anyone else into the weeds with me.

What I'm left wondering:
- The commentaries are written from an Ecological Dynamics viewpoint. What would Information Processing commentaries look like?
- In volleyball, we often talk about defenders needing to be stopped/balanced when the opponent attack happens. I find information in the target article that suggests that movement during opponent contact could be either helpful or hurtful. How can I better understand when movement at opponent contact is useful?
- Araújo and Kirlik's article draws a distinction between "representative design" and "ecological validity", writing that many researchers use the latter term when they are really talking about the former (p. 163). I still don't think I understand the distinction.
- Probably the largest question I am left with is if the two motor learning camps have made any movement towards each other and if the two stream system is part of such compromise. As primarily a practitioner, I tend to be more pragmatic in my approach to these theories. I want to use what gets results, meaning the best learning and skill performance. I don't know how to do that in a way that doesn't run afoul of one of the two world views. A coherent, consistent framework is very important to me as a coach so I find this dissonance difficult to reconcile within the realm of my practice.


  1. Responding to: "How can I better understand when movement at opponent contact is useful?"

    One way that movement on or before opponent contact can be beneficial is when you know that their won't be enough time to react fast enough, or coordinate and initiate an appropriate skilled movement response. So, when you know you won't have enough time, you could benefit from moving early (a.k.a. "cheating"). Obviously, that comes with a cost. You could get it wrong. That's part of the rub when it comes to anticipation and prediction. What if what the defender is seeing is all a set up, and the attacker is being deceptive or tricky? You know? The way I see it, is like this. If waiting and being disciplined puts you at a disadvantage, to the point where you are almost certainly not going to be able to react fast enough to make the play. Then yeah, at that point I think it can be advantageous to move before the opponent contacts the ball. In those situations, I accept that it might help and it might hurt.

  2. Responding to: "Araújo and Kirlik's article draws a distinction between "representative design" and "ecological validity", writing that many researchers use the latter term when they are really talking about the former (p. 163). I still don't think I understand the distinction."

    How I see it is that many lab-based research tasks can be easier to control and study, however such lab-based simulations on visual perception often result in performance that differs from that which we observe in natural settings. I like the way Van der Kamp and colleagues (2008) put it. Noting concerns about the validity of such lab studies, Van der Kamp and colleagues said, "the studies did not preserve the functional coupling between perception and action." For example, computer simulations or video occlusion tasks are two-dimensional "which may de-emphasise certain sources of information available in the optical structure of the environment (e.g. depth information, binocular invariants)" (Williams, 1999, p. 244).

    Essentially, there just saying the same thing that Professor Rob Gray always says, "Keep it coupled..."

    Davids, K., Williams, A.M., & Williams, J.G. (Eds.). (1999). Visual Perception and Action in Sport (1st ed.). Routledge.


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