(De)synchronization of advanced visual information and ball flight characteristics constrains emergent information-movement couplings during one-handed catching.

Advance visual information of a projection action and ball flight information is important for organizing dynamic interceptive actions like catching. However, how the central nervous system (CNS) manages the relationship between advance visual information and emerging ball flight information in regulating behavior is less well understood. Here, we sought to examine the extent that advance visual information to the CNS constrains regulation of catching actions by synchronizing and desynchronizing its relationship with ball trajectory characteristics. Novel technology was used to present video footage of an actor throwing a ball at three different speeds, integrated with information from a real ball projected by a machine set to the three speeds. The technology enabled three synchronized and six desynchronized conditions between advance visual information and subsequent ball flight trajectories. Catching performance, kinematic data from the catching hand and gaze behaviors were recorded. Findings revealed that desynchronization of video images of ball projection shaped emergent catching behaviors. Footage of slower throws, paired with faster ball projection speeds, caused catching performance decrements. Timing in early phases of action was organized by the CNS to match the advance visual information presented. In later phases, like the grasp, ball flight information constraints adapted and regulated behaviors. Gaze behaviors showed increased ball projection speed resulted in participants tracking the ball for a smaller percentage of ball flight. Findings highlighted the role of the two visual systems in perception and action, implicating the importance of coupling advanced visual information and ball flight to regulate emergent movement coordination tendencies during interceptive behaviors.

Emergent perception-action couplings regulate postural adjustments during performance of externally-timed dynamic interceptive actions.

Studies of postural coordination during performance of externally-timed interceptive actions, such as catching a ball, have been infrequent, with advanced visual information from a thrower's actions towards a catcher, typically excluded in experimental task constraints. Yet previous research suggests that manipulating participant access to such information alters their hand movements and gaze behaviours when catching. In this study, we manipulated participant access to advanced information of a thrower's actions, and from ball flight, while recording whole body kinematic and kinetic data to investigate effects on postural control during performance of interceptive actions. Twelve participants attempted to make or simulate performance of one-handed catches in three experimental conditions: when facing integrated videos of advanced visual information and ball flight only, videos of a thrower's actions only, and of ball flight only. Findings revealed when integrating advanced visual information and ball flight, and when participants were provided with ball flight information only, lower limb adjustments were primarily used to regulate posture. However, movement was initiated earlier when advanced visual information was available prior to ball flight, resulting in more controlled action and superior catching performance in the integrated condition. When advanced visual information was presented without ball flight, smaller displacements were observed in lower limb joint angles, resulting in upward projection of the centre of mass, compared to a downward trajectory when ball flight information was available, in the integrated video and ball flight, and ball-flight only conditions. Results revealed how postural coordination behaviors are dependent on specific informational constraints designed into experiments, implying that integration of task constraints in studies of human perception and action needs careful consideration.

An integrated ball projection technology for the study of dynamic interceptive actions.

Dynamic interceptive actions, such as catching or hitting a ball, are important task vehicles for investigating the complex relationship between cognition, perception, and action in performance environments. Representative experimental designs have become more important recently, highlighting the need for research methods to ensure that the coupling of information and movement is faithfully maintained. However, retaining representative design while ensuring systematic control of experimental variables is challenging, due to the traditional tendency to employ methods that typically involve use of reductionist motor responses such as buttonpressing or micromovements. Here, we outline the methodology behind a custom-built, integrated ball projection technology that allows images of advanced visual information to be synchronized with ball projection. This integrated technology supports the controlled presentation of visual information to participants while they perform dynamic interceptive actions. We discuss theoretical ideas behind the integration of hardware and software, along with practical issues resolved in technological design, and emphasize how the system can be integrated with emerging developments such as mixed reality environments. We conclude by considering future developments and applications of the integrated projection technology for research in human movement behaviors.

Temporal and spatial occlusion of advanced visual information constrains movement (re)organization in one-handed catching behaviors.

Dynamic interceptive actions are performed under severe spatial and temporal constraints. Here, behavioral processes underpinning anticipation in one-handed catching were examined using novel technology to implement a spatial and temporal occlusion design. Video footage of an actor throwing a ball was manipulated to create four temporal and five spatial occlusion conditions. Data from twelve participants' hand kinematics and gaze behaviors were recorded while attempting to catch a projected ball synchronized with the video footage. Catching performance decreased with earlier occlusion of the footage. Movement onset of the catching hand and initiation of visual ball tracking emerged earlier when footage of the thrower was occluded at a later time point in the throwing action. Spatial occlusion did not affect catching success, although movement onset emerged later when increased visual information of the actor was occluded. Later movement onset was countered by greater maximum velocity of the catching hand. Final stages of action (e.g., grasping action of the hand) remained unchanged across both spatial and temporal conditions suggesting that later phases of the action were organized using ball flight information. Findings highlighted the importance of maintaining information-movement coupling during performance of interceptive actions, since movement behaviors were continuously (re)organized using kinematic information from a thrower's actions and ball flight information.

Gaze behaviors of goaltenders under spatial-temporal constraints.

It is still not known what underlies successful performance in goaltending. Some studies have reported that advanced cues from the shooter's body (hip, kicking leg or support leg) are most important (Savelsbergh, G. J. P., Williams, A. M., Van der Kamp, J., & Ward, P. (2002). Visual search, anticipation and expertise in soccer goalkeepers. Journal of Sports Sciences, 20, 279-287; Savelsbergh, G. J. P., Williams, A. M., Van der Kamp, J., & Ward, P. (2005). Anticipation and visual search behaviour in expert soccer goalkeepers. Ergonomics, 48, 1686-1697; Williams, A. M., & Burwitz, L. (1993). Advanced cue utilization in soccer. In T. Reilly, J. Clarys, & A. Stibbe (Eds.), Science and football II (pp. 239-243). London, England: E&FN Spon), while others have found that the early tracking of the object prior to and during flight is most critical (Bard, C., & Fleury, M. (1981). Considering eye movement as a predictor of attainment. In: I. M. Cockerill, & W. M. MacGillvary (Eds.), Vision and Sport (pp. 28-41). Cheltenham, England: Stanley Thornes (Publishers) Ltd.). These results are similar to those found in a number of interceptive timing studies (Land, M. F., & McLeod, P. (2000). From eye movements to actions: How batsmen hit the ball. Nature Neuroscience, 3, 1340-1345; Ripoll and Fleurance, 1988; Vickers, J. N., & Adolphe, R. M. (1997). Gaze behaviour during a ball tracking and aiming skill. International Journal of Sports Vision, 4, 18-27). The coupled gaze and motor behavior of elite goaltenders were determined while responding to wrist shots taken from 5 m and 10 m on ice. The results showed that the goalies faced shots that were significantly different in phase durations due to distance (5 versus 10 m), but this was not a factor in making saves. Instead, the ability to stop the puck was dependent on the location, onset and duration of the final fixation/tracking gaze (or quiet eye) prior to initiating the saving action. The relative onset of quiet eye was significantly (p<.001) earlier (8.6%) and the duration was longer on saves (M=80.5%; 952.3 ms) compared to goals (onset 18.86%; M=70.1%, 826.1 ms). The quiet eye was located on the puck/stick during the preparation and execution of the shot in 70.53% of all trials, or on the ice in front of the release point of the puck (25.68%) and rarely on the body of the shooter (2.1%). The results are discussed within the context of current research on goaltending with specific emphasis on the timing of critical cues and the effect of tasks constraints.