To know or not to know: influence of explicit advance knowledge of occlusion on interceptive actions

Tijtgat, Pieter; Bennett, Simon J.; Savelsbergh, Geert J.P.; Clercq, Dirk De; Lenoir, Matthieu

doi:10.1007/s00221-011-2846-1

Cited by 15 publications

(12 citation statements)

References 45 publications

(61 reference statements)

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“…A number of studies have reported that visual occlusion can influence the movement pattern in manual catching (Dessing, Oostwoud-Wijdenes, Peper, & Beek, 2009; Mazyn, Savelsbergh, Montagne, & Lenoir, 2007; Tijtgat, Bennett, Savelsbergh, De Clercq, & Lenoir, 2011). Mazyn et al (2007) asked participants to catch an approaching ball with full vision and in a visual occlusion condition in which the ball was occluded at the onset of catching hand-movement.…”

Section: Model-based Control: Is An Internal Model Sufficient?mentioning

confidence: 99%

On-line and model-based approaches to the visual control of action

2015

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Two general approaches to the visual control of action have emerged in last few decades, known as the on-line and model-based approaches. The key difference between them is whether action is controlled by current visual information or on the basis of an internal world model. In this paper, we evaluate three hypotheses: strong on-line control, strong model-based control, and a hybrid solution that combines on-line control with weak off-line strategies. We review experimental research on the control of locomotion and manual actions, which indicates that (a) an internal world model is neither sufficient nor necessary to control action at normal levels of performance; (b) current visual information is necessary and sufficient to control action at normal levels; and (c) under certain conditions (e.g. occlusion) action is controlled by less accurate, simple strategies such as heuristics, visual-motor mappings, or spatial memory. We conclude that the strong model-based hypothesis is not sustainable. Action is normally controlled on-line when current information is available, consistent with the strong on-line control hypothesis. In exceptional circumstances, action is controlled by weak, context-specific, off-line strategies. This hybrid solution is comprehensive, parsimonious, and able to account for a variety of tasks under a range of visual conditions.

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Section: Model-based Control: Is An Internal Model Sufficient?mentioning

confidence: 99%

On-line and model-based approaches to the visual control of action

2015

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“…Along these lines, psychophysical experiments have suggested short-term adaptations in the motion extrapolation process by observing that early and late occlusion of the visual target may affect differentially the spatial features of catching movements, depending on the presentation order of the occlusion conditions [77]. In addition to short-term mechanisms, abstract long-term categorical representations of the target motion [78], as well as explicit advance information [79] can contribute to this process. Moreover, the evidence that occluding vision for short intervals before interception of vertically free-falling targets with natural and non-natural laws of motion can produce errors consistent with temporal estimates based on an implicit knowledge of the causal effects of Earth's gravity implies a role also for internal models of the external environment [80].…”

Section: Introductionmentioning

confidence: 99%

Catching What We Can't See: Manual Interception of Occluded Fly-Ball Trajectories

2012

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Control of interceptive actions may involve fine interplay between feedback-based and predictive mechanisms. These processes rely heavily on target motion information available when the target is visible. However, short-term visual memory signals as well as implicit knowledge about the environment may also contribute to elaborate a predictive representation of the target trajectory, especially when visual feedback is partially unavailable because other objects occlude the visual target. To determine how different processes and information sources are integrated in the control of the interceptive action, we manipulated a computer-generated visual environment representing a baseball game. Twenty-four subjects intercepted fly-ball trajectories by moving a mouse cursor and by indicating the interception with a button press. In two separate sessions, fly-ball trajectories were either fully visible or occluded for 750, 1000 or 1250 ms before ball landing. Natural ball motion was perturbed during the descending trajectory with effects of either weightlessness (0 g) or increased gravity (2 g) at times such that, for occluded trajectories, 500 ms of perturbed motion were visible before ball disappearance. To examine the contribution of previous visual experience with the perturbed trajectories to the interception of invisible targets, the order of visible and occluded sessions was permuted among subjects. Under these experimental conditions, we showed that, with fully visible targets, subjects combined servo-control and predictive strategies. Instead, when intercepting occluded targets, subjects relied mostly on predictive mechanisms based, however, on different type of information depending on previous visual experience. In fact, subjects without prior experience of the perturbed trajectories showed interceptive errors consistent with predictive estimates of the ball trajectory based on a-priori knowledge of gravity. Conversely, the interceptive responses of subjects previously exposed to fully visible trajectories were compatible with the fact that implicit knowledge of the perturbed motion was also taken into account for the extrapolation of occluded trajectories.

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“…The aim of this study was to examine the effects of visual occlusion created by the wall on goalkeeper performance during free kicks. Because the wall causes the ball to come into view later we predicted a delayed movement onset [12][13]. Since this leaves less time to complete the interception and because the wall occludes the initial ball motion, we expected the wall to reduce performance and particularly so for shorter flight times [14][15][16].…”

Section: Discussionmentioning

confidence: 99%

“…For the time-pressed task of blocking penalty kicks goalkeeper performance strongly depends on seeing the kicker [4][5][6][7][8]; free kicks allow more time for online control and goalkeeper performance in this context does not critically depend on seeing the kicker [9][10][11]. Early occlusion of the ball trajectory will likely result in later initiation and reduce catching performance [12][13], due to less information and less time being available to guide the interception.…”

Section: Introductionmentioning

confidence: 99%

A goalkeeper’s performance in stopping free kicks reduces when the defensive wall blocks their initial view of the ball

Valkanidis¹,

Craig²,

Cummins³

et al. 2019

Preprint

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Free kicks are an important goal scoring opportunity in football. It is an unwritten rule that the goalkeeper places a wall of defending players with the aim of making this harder for the attacking team. However, the defensive wall can occlude the movements of the kicker, as well as the initial part of the ball trajectory. A ball coming into view later will likely delay movement initiation and possibly affect performance. Here, we used virtual reality to investigate the effect of the visual occlusion of the initial ball trajectory by the wall on the performance of expert and novice goalkeepers. We showed that movements were initiated significantly later when the wall was present, but not by the same amount as the duration of occlusion (~200ms, versus a movement delay of ~70-90ms); movements were thus initiated sooner after the ball came into view, based on less accumulated information. For both novice and expert goalkeepers this delayed initiation significantly affected performance (i.e., 1.5-3.6cm larger spatial hand error, 7-8% fewer interceptions). These performance reductions were significantly larger for shorter flight times, reaching increased spatial errors of 2.8-4.5cm and 11-13% fewer interceptions. Further analyses showed that the wall-induced performance reduction did not differ significantly between non-curved and curved free kicks. The wall induced early movement biases, but only for ball trajectories with curve in the same direction as the required movement; the effect of these biases was negative, away from the final ball position. In two additional experiments (with variations in initial forward and sideward ball position, respectively) largely consistent results were found (i.e., the wall-induced performance reduction was smaller and failed to reach significance with variations in initial sideward ball position). These results may suggest that, certainly for expert free kick takers who are very good at shooting hard free kicks that avoid the wall (reducing its function as a block), goalkeepers could consider omitting the wall.

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To know or not to know: influence of explicit advance knowledge of occlusion on interceptive actions

Cited by 15 publications

References 45 publications

On-line and model-based approaches to the visual control of action

On-line and model-based approaches to the visual control of action

Catching What We Can't See: Manual Interception of Occluded Fly-Ball Trajectories

A goalkeeper’s performance in stopping free kicks reduces when the defensive wall blocks their initial view of the ball

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