Cognitive control of series of actions:
Damien Lafont, PhD damien_lafont@yahoo.fr
A.S.Montferrand Tennis, France
2008
Outlines Introduction Origin of the study Observations Perspectives
Damien Lafont
2008
Origin of the study Roger Federer - Backhand / Post-impact
Š Advantage Tennis - McCarron
Damien Lafont
2008
Origin of the study Roger Federer - Forehand / Post-impact
Damien Lafont
2008
Observations Federer shows a specific gaze behavior during the hitting phase :
Fixation on the contact zone during the follow-through Unique signature ?
Damien Lafont
2008
High-speed photo analysis Data + 9000 photos
Advantage Tennis - Mike McCarron Pablo Sanfrancisco Vandystadt AFP Reuters Associated Press Getty Images
ATP & WTA tournaments – Top 100 Backhand & forehand groundstrokes Hitting phase Impact / Post-impact
Gaze control Involves movements of EYES, HEAD and TRUNK These are coordinated in a way that allows for both flexibility of movement and stability of gaze (Land, 2006) Damien Lafont
2008
3 hitting profiles Backhand AND forehand fixation « Total fixation » Backhand OR forehand fixation or « intermittent » fixation « Partial fixation » No fixation
Damien Lafont
2008
« No fixation »
« Fog zone » Different head positions Damien Lafont
2008
« No fixation »
Damien Lafont
2008
« Partial fixation »
© AP © Advantage Tennis - McCarron
Damien Lafont
© Bakalian - Fedephoto
2008
« Partial fixation »
© AP
© AP
Damien Lafont
2008
« Total fixation »
Damien Lafont
2008
« Total fixation »
Damien Lafont
2008
ATP - Top 100 ATP ranking 8/20/2007
Top 10
1. Federer,
Nadal, Djokovic, Davydenko, Roddick, Blake, Gonzalez, Robredo, Berdych, Haas, Youzhny, Ljubicic, Gasquet, Canas, Ferrer, Hewitt, Moya, Baghdatis, Murray, Chela, Ferrero, Mathieu, Monaco, Nalbandian, Safin, Nieminen, Tursunov, Almagro, Volandri, Soderling, Starace, Melzer, Karlovic, Stepanek, Verdasco, Hrbaty, Ancic, Kohlschreiber, Andreev, Simon, Clement, Lee, Santoro, Monfils, Gicquel, Montanes, Querrey, Calleri, Becker, Fish, Tipsarevic, Mayer, Hernandez, Eschauer, Rochus, Malisse, Wawrinka, Bjorkman, Del Potro, Massu, Llodra, Lopez, Benneteau, Spadea, Koubek, Ginepri, Russell, Dancevic, Acasuso, Mahut, Delic, Johansson, Vassallo Arguello, Tsonga, Hartfield, Berlocq, Seppi, Roitman, Grosjean, Lapentti, Korolev, Vliegen, Zabaleta, Berrer, Garcia-Lopez, Horna, Bolelli, Guccione, Gulbis, Serra, Luczak, Henman, Kunitsyn, Gabashvili, Haase, Goldstein, Pavel, Pless, Navarro Pastor, Zverev.
Total fixation : 10 players Partial fixation : 36 players No fixation Damien Lafont
2008
ATP - Top 100 ATP Ranking 8/25/2008
Top 10
1.Nadal, Federer, Djokovic, Ferrer, Davydenko, Murray, Nalbandian, Roddick, Blake, Wawrinka, Gonzalez, Gasquet, Verdasco, Karlovic, Robredo, Simon, Del Potro, Almagro, Tsonga, Kiefer, Youzhny, Berdych, Andreev, Cilic, Mathieu, Kohlschreiber, Tursunov, Ancic, Lopez, Stepanek, Seppi, Monaco, Monfils, Soderling, Fish, Schuettler, Nieminen, Llodra, Haas, Gulbis, Gicquel, Moya, Ljubicic, Safin, Tipsarevic, Baghdatis, Bolelli, Melzer, Calleri, Ferrero, Granollers, Canas, Hanescu, Querrey, Hewitt, Benneteau, Schwank, Montanes, Santoro, Ginepri, Darcis, Devilder, Chela, Lapentti, Johansson, Garcia-Lopez, Rochus, Serra, Grosjean, Troicki, Kunitsyn, Lu, Gremelmayr, Navarro, Sela, Starace, Clement, Hernandez, Chardy, Minar, Daniel, Fognini, Mahut, Gabashvili, Bellucci, Guccione, Andujar, Reynolds, Gil, Stakhovsky, Rochus, Volandri, Zverev, Horna, Levine, Haase, Korolev, Berrer, Karanusic.
Total fixation: 8 players Partial fixation: 31 players No fixation Damien Lafont
2008
Men Grand Slam Champions (since 1999) Total Federer, Nadal, Hewitt, Ferrero, Kafelnikov
Partial Safin, Kuerten, Moya, Gaudio, Sampras, ? Costa, Agassi, Johansson
No Ivanisevic, Korda Damien Lafont
2008
Men Number ones (since 1997) Total Federer, Nadal, Hewitt, Ferrero, Kafelnikov
Partial Safin, Kuerten, Roddick, Sampras, ? Agassi
No Rafter Damien Lafont
2008
Discussion Current hitting model « Watch the ball!» The player should try to watch the ball throughout its entire flight
≠ OBSERVATIONS
Damien Lafont
2008
A new model ? The best players : Fix the contact zone after the impact Switch from the ball to the contact zone BALL CONTACT ZONE
Damien Lafont
2008
Conclusion The post-impact ÂŤ fixation Âť on the contact zone is a common characteristic of elite players Men Women?
A key fundamental of the game?
Damien Lafont
2008
Observations Experts in many tasks show similar fixation stage during the hitting phase
High-level athletes’ performances suggest that there are certainly fundamental benefits in adopting this gaze behaviour jus after contact. Damien Lafont
2008
Effects
Biomechanicals benefits? Mental benefits of the fixation? Cognitive effects? Damien Lafont
2008
Context People’s performance at a given time is influenced by what they plan to do next. In sport, reading, music reading, typing or driving there are benefits to think and see ahead.
Damien Lafont
2008
Context Table tennis and other ball games : “The secret”: to know what the ball is going to do as far ahead as possible •
to allow time for the planning and execution of accurate responses.
Players need to determine the future trajectory of the ball and the timing of contact with it (Land and McLeod, 2000). Damien Lafont
2008
Context Ripoll et al. (1988) International table-tennis players anticipate the bounce and made a saccade to a point close to the bounce point. Land and McLeod (2000) Same thing in cricket, where the ball also bounces before reaching the batsman.
Damien Lafont
2008
Context Eye movements in reading are constrained to a linear progression of fixations to the right across the page (Rayner, 1998; Radach et al., 2004). Similarly, in music reading gaze must move progressively to the right (Land, 2006).
In copy typing, typists of all skill levels attempt to keep the eyes about 1s ahead of the currently typed letter. Damien Lafont
2008
Context Clear relationship between direction of gaze and steering (Land and Lee, 1994; Land, 2006)
drivers spent much of their time looking at the ‘tangent point’ on the up-coming bend.
Many complex tasks require the integration of visual information mainly gained in the first part of the action
Benefit of early anticipation Damien Lafont
2008
Context Lafont (2007, 2008) Top tennis players hold their head still when hitting the tennis ball, apparently inhibiting their desire to watch the ball after it leaves the racquet. By contrast, less accomplished tennis players do not hold their head still when hitting the tennis ball, apparently unable to inhibit their desire to watch the ball after it leaves the racquet. Damien Lafont
2008
Context Vickers (1992, 2004) In golf, almost all novices follow the ball with their eyes after they hit it ... ... whereas the good player maintains fixation on the same location at the point of impact after the ball is hit
Damien Lafont
2008
Context Holding the head still at the time of hitting the ball is likely to permit a more effective hit than allowing the head to turn Biomechanically, head stability is likely to allow for greater body stability altogether. Cognitively, holding the head still may heighten the player’s focus on the place and time of contact.
Damien Lafont
2008
Now The early part of the movement / ball trajectory (before contact) has been widely studied and is recognized as the most critical. However, there is much to learn about the way that eye should point in the transition of consecutive actions. Ex: When anticipation should be initiated ? Damien Lafont
2008
Objectives In many activities : benefits of early preparation But can our efforts to prepare actually undermine our chances for success? Can anticipation be detrimental to effective performance in some circumstances
Damien Lafont
? 2008
Hypotheses Visual information before contact Experts look at points that are particularly informative for the ongoing action Feedback about the status of the ongoing movement. Information on the ball’s trajectory Planning the ensuing motor response.
What happens after contact?
Damien Lafont
2008
Hypotheses First step hypothesis Deprivation of visual feedback on the ball trajectory doesn’t change the movement accuracy.
≠Prediction from previous observations People should do better when the ball disappears from view after it is hit than when the ball does not disappear from view after it is hit At least if the disappearance time is not too long !
Removing visual feedback of post-contact trajectory will have beneficial effects on subsequent movements. Damien Lafont
2008
Hypotheses Experts : “dead-eye” gaze Prevents the inflow of visual inputs that could interfere with the aiming commands set earlier
i.e. the numerous fixations as the ball traverses along its path
More time without interference from other sources. Limits the number of variables to be controlled.
Limits inaccurate motor output Damien Lafont
2008
Hypotheses EEG – Vickers et Crews (2002) Golf – brain activation and gaze control
Damien Lafont
2008
Hypotheses Natural impulse to anticipate the response of our actions, to evaluate the possible outcomes.  Eye movement even before contact.
To properly see and react, we must abandon our plans and preparations, our intents and expectations
Damien Lafont
2008
Hypotheses When subjects can not see the ball ... They receive no concurrent visual feedback about the progress of the movement. The immediate result of the movement is not available. The attention is not directed to the effect of the action but to the action itself.
It would allow the players ... to place less value on the outcome of their shots to abandon expectations and intention, to stay on the process
... being comfortable with not knowing ...! Damien Lafont
2008
Hypotheses Abrams et al. (1990) Visual-feedback processing related to the production of aimed movements Roles played by different sources of visual feedback
vision of the effector and the target
3 eye-movement hypotheses that describe the coordination of gaze when aiming at near targets.
Damien Lafont
position-only movement-only movement-plus-position 2008
Hypotheses Alternative hypothesis : A switch from the eye “time-locked” with the ball movement to a stable gaze anchored on the contact point would improve performance. “Gaze anchoring”
The differences between expert and less skilled performers the organization of the information chain the simplification of visual input.
Damien Lafont
2008
Hypotheses How we control the serial order of our behaviors Rosenbaum et al. (2007) When we engage in behaviors that have distinct elements, the elements of the behaviors must be ordered correctly. Rosenbaum (1991) Hierarchical treatment of information. 
Establishing a constraint hierarchy – a set of prioritized requirements defining the task to be performed - is one of the most important aspects of motion planning (Jax et al., 2003).
Hierarchical organization for behavioral plans Damien Lafont
2008
Hypotheses Land and Furneaux (1997) - ball games: • •
to know what the ball is going to do as far ahead as possible time for the planning and execution of accurate responses.
The most relevant information on the ball is gathered during the first part of the trajectory. Most of studies highlight the potential benefits of early anticipation.
Anticipating Damien Lafont
Over-anticipating 2008
Hypotheses Observations : the capture of subsequent cues and evaluation of the upcoming event is not immediately useful after contact. In specific situations, visual search initiated too early after contact would be even maladaptive for movement. The period of time after contact when the gaze is stable serves as inhibitory process of too early anticipation process for the next action.
“Time window� Damien Lafont
... When anticipation should be initiated ?
2008
Hypotheses Inhibitory control: an important part of performance Observations:  greater capacity for inhibition (or future eye positions)
among top players than among lesser players.
Importance of inhibition in the control of movement sequences
Damien Lafont
2008
Perspectives To gain a more precise picture of the role of visual feedbacks underlying the decision processes To better understand more fully the contribution of the transition phase between consecutives actions. In sport: to obtain a more precise idea of what the athletes are required to do, in terms of actions and cognitive processes.  Damien Lafont
Training purposes. 2008
Other perspectives … Video Analysis Fixation duration?
Eye-tracker technology Coupled gaze and body movement measurements
Biomechanics Effects on balance, on impact location …
Mental Concentration, control, confidence … Pressure? Damien Lafont
2008
Thank you for your attention
Damien Lafont
2008
References Lafont, D. (2008). Six good reasons to keep your eyes off the ball, ITF Coaching and Sport Science Review, 44. Lafont, D. (2008). Gaze control during the hitting phase in tennis: a preliminary study, International Journal of Performance Analysis in Sport, 8(1), 85-100. Lafont, D. (2008). From the ball to the contact zone: Evidence of visual referential switch among elite tennis players, Le tennis dans la société de demain, Dijon, France, April 2008. Lafont, D. (2007). High-speed photo analysis of top players’ gaze behaviour, Tennis Science and Technology 3, ITF publication, London, 227-233. Lafont, D. (2007). Towards a new hitting model in tennis, International Journal of Performance Analysis in Sport, 7(3), 104-114. Lafont, D. (2007). Watch the ball? ITF Coaching and Sport Science Review, 43, p.11. 2008
other perspectives ...
Damien Lafont
2008
Perspectives Nature of the fixation skill? Learned Natural Modelling
Š Tennis Magazine
Damien Lafont
2008
Perspectives - Psychology FOCUS on the BALL FOCUS on the CONTACT ZONE
Damien Lafont
Outcome focus No control Concentration Present Control Confidence
Flow & Zone
Ford et al. (2002)
2008
Perspectives - Video analysis Duration of the « fixation » stroke types
Data base – high level tennis players Jeff Counts 1/60 s
John Yandell
Damien Lafont
1/250 s 1/125 s
2008
The mysterious question of gender difference ...
Damien Lafont
2008
WTA - Top 100 WTA Ranking 8/27/2007 1. Henin, Sharapova, Jankovic, Kuznetsova, Ivanovic, Chakvetadze, Mauresmo, Petrova, Williams, Bartoli, Hantuchova, Schnyder, Dementieva, Williams V., Vaidisova, Safina, Hingis, Golovin, Peer, Bammer, Bondarenko, Li, Safarova, Srebotnik, Schiavone, Garbin, Mirza, Zvonareva, Santangelo, Sugiyama, Szavay, Radwanska, Krajicek, Medina Garrigues, Stosur, Kirilenko, Razzano, Danilidou, Loit, Muller, Azarenka, Dulko, Paszek, Kanepi, Tu, Poutchkova, Peng, Shaughnessy, Nakamura, Vakulenko, Vinci, Morigami, Bondarenko, Dechy, Sequera, Vesnina, Knapp, Dushevina, Likhovtseva, Granville, Rezai, Meusburger, Cibulkova, Kudryavtseva, Govortsova, Chan, Kerber, Pratt, Molik, Shvedova, Bremond, King, Tanasugarn, Osterloh, Dominguez Lino, Camerin, Yan, Craybas, Ruano Pascual, Gallovits, Zakopalova, Harkleroad, Pennetta, Olaru, Poutchek, Wozniacki, Rodionova, Benesova, Kostanic, Dellacqua, Pin, Wozniak, Cohen-Aloro, Bacsinszky, Arn, Cornet, Obzilzer, Amanmuradova, Bychkova, Bardina
Total fixation: 1 player ?! Partial fixation: 18 players Damien Lafont
2008
Women Grand Slam Champion (since 1999) Total Graf, Henin, Clijters
Partial Seles, V. Williams, Sharapova, Ivanovic
No
Damien Lafont
Mauresmo, Williams S., Kusnetsova, Dementieva, Pierce, Davenport, Hingis, Sanchez 2008
Women Number ones (since 1997) Total Henin, Clijters, Graf
Partial Sharapova, V. Williams, Seles
No Mauresmo, S. Williams S., Hingis, Davenport Damien Lafont
2008
« Total fixation » - Henin
© AFP
Damien Lafont
2008
« Total fixation » - Graf
© Advantage Tennis - McCarron
Damien Lafont
2008
Example of experimental setting
Damien Lafont
2008
Experiment Design Focus on the transition phase •
i.e. the interval between two consecutives actions.
Contributions of different visual feedbacks during the phase of early information for movement accuracy Video-based experimental setting. To determine whether post-impact visual information on ball and target serve any useful purpose for performance and decision making. Damien Lafont
2008
Experiment Design Video game Open-source (can be modified)
2 experiments Visual conditions Task: move a cursor across the scress and hit a
"ball” toward a specified target (joystick)
Damien Lafont
2008
Experiment Temporal occlusion In unconstrained setting (where perceptual information is continuously available) the eyes usually arrive at the target before the initial impulse in a limb movement (Abrams et al., 1990). The eyes tend to keep track of a dynamic object (the ball) Occluding part of the post-contact trajectory will force the participants to switch attention from their usual visual pattern. Damien Lafont
2008
Experiment Temporal occlusion 2 ball conditions Visible-ball condition (the control condition) 
Complete concurrent feedback regarding the progress of the ball movements.
Ball disappearance (when the ball contacts the cursor).  
Damien Lafont
Only partial visual information on the post-contact event. Vary how long the ball disappears from view after it is hit by the cursor (gradually reducing the disappearance time).
2008
Experiment 1
Damien Lafont
2008
Experiment 2
Damien Lafont
2008
Experiment Variations 2D movements for the cursor. Disappearance time of the ball after contact. To increase the speed of the ball. Target visibility.
Damien Lafont
2008
Experiment Variations - from 1D to 2D
Damien Lafont
2008
Experiment Variations – Disappearance time Gradually reduce how long the ball disappears from view after it is hit by the cursor.
It will allow to determinate the limits of the critical period after contact.
Variations – Ball speed The subjects could be pressured to minimize their movement latency.
Damien Lafont
Reduce the amount of time available to execute the movement.
2008
Experiment Variations - Target disappearance
Damien Lafont
2008
Experiment Result estimation Trade-off between facilitation of accurate movement execution and detrimental effects. Reaction and movement times. Accuracy and speed of each trial.  Exp.1: time to destroy the two lines (i.e. all bricks).  Exp.2: 1 point for each ball/target contact.
Damien Lafont
2008
Experiment Results / Quality of performance ...
?
1 - No difference in accuracy between movements perform under full and partly visual feedback. 2 - The accuracy of participant decreases 3 - Increase of accuracy Evidence for the potential benefit of a switch
of visual referential in the post-contact phase. Identify the “time window” Damien Lafont
2008