Action preferences and the anticipation of action outcomes

Skilled performers of time-constrained motor actions acquire information about the action preferences of their opponents in an effort to better anticipate the outcome of that opponent's actions. However, there is reason to doubt that knowledge of an opponent's action preferences would unequivocally influence anticipatory responses in a positive way. It is possible that overt information about an opponent's actions could distract skilled performers from using the advance kinematic information they would usually rely on to anticipate actions, particularly when the opponent performs an ‘unexpected’ action that is not in accordance with his or her previous behaviour. The aim of this study was to examine how the ability to anticipate the outcome of an opponent's actions can be influenced by exposure to the action preferences of that opponent. Two groups of skilled handball goalkeepers anticipated the direction of penalty throws performed by opponents before and after a training intervention that provided situational probability information in the form of action preferences (AP). During the training phase participants in an AP-training group anticipated the action outcomes of two throwers who had a strong preference to throw in one particular direction, whilst participants in a NP-training group viewed players who threw equally to all directions. Exposure to opponents who did have an action preference during the training phase resulted in improved anticipatory performance if the opponent continued to bias their throws towards their preferred direction, but decreased performance if the opponent did not. These findings highlight that skilled observers use information about action preferences to enhance their anticipatory ability, but that doing so can be disadvantageous when the outcomes are no longer consistent with their generated expectations.     

Response bias in judging deceptive movements

Two not mutually exclusive explanations, perceptual and motor expertise, account for the finding that experts outperform novices in recognizing deceptive actions from bodily (kinematic) cues. The aim of the present study was twofold: First, we sought to examine the impact of motor and perceptual expertise on distinguishing deceptive and non-deceptive actions. Second, we tested the hypothesis that differences in perceptual judgments on deceptive movements vs. non-deceptive movements do not necessarily need to be caused by either perceptual or motor expertise differences, but can also be a result of response bias. Skilled handball players (field players and goalkeepers) and novices had to detect whether a penalty-taker shot or faked a shot at the goal. Signal detection theory (SDT) analysis revealed that skilled handball players outperformed novices in discriminating shots from fakes. No differences in perceptual sensitivity were found between the goalkeepers and the field players. However, SDT analysis showed that goalkeepers were significantly biased to judge movements as deceptive, while neither field players nor novices showed this response bias.     

How perceiving additional targets modifies teams’ tactical behavior during football small-sided games

This study aimed to measure how the change on targets information modifies teams’ tactical behavior during football small-sided games. 20 male senior professional players divided in 4 teams of 5 players participated in the study. Each team played two small-sided games, one with 2 official targets with goalkeeper and one with 6 small targets. Positional data of each player were recorded using a 15 Hz portable GPS. The distance between the centers of gravity (CG) of both team, the stretch index and the relative stretch index were measured and differences accessed via standardized differences, coefficient intervals and meta-analysis procedures. A moderate increase on the distance between the CG of each team and a small decrease on the stretch index and on the relative stretch index from 2 targets to the 6 targets games was observed. It was also identified that pitch location affected the interaction between teams. When the game was played in lateral corridors or defensive sectors, the differences between game conditions increased. Emphasizing the information for attacking team to shoot at goal, by manipulating the number of targets constrained tactical behavior of teams. The amplification of specific information on small-sided games can help coaches to promote players and teams’ emergent adapted behaviors.     

Continuous visual control of interception

People generally try to keep their eyes on a moving target that they intend to catch or hit. In the present study we first examined how important it is to do so. We did this by designing two interception tasks that promote different eye movements. In both tasks it was important to be accurate relative to both the moving target and the static environment. We found that performance was more variable in relation to the structure that was not fixated. This suggests that the resolution of visual information that is gathered during the movement is important for continuously improving predictions about critical aspects of the task, such as anticipating where the target will be at some time in the future. If so, variability in performance should increase if the target briefly disappears from view just before being hit, even if the target moves completely predictably. We demonstrate that it does, indicating that new visual information is used to improve precision throughout the movement.     

Contextual interference and augmented feedback: is there an additive effect for motor learning?

Learning to perform a skilled behavior is affected by the context of the practice session and the frequency of augmented feedback. We studied the combined effect of these variables in the acquisition of a ballistic, bi-directional lever movement pattern involving four different target locations as measured by performance in practice, retention, and transfer tests. Augmented feedback was presented in either an every-trial or a faded schedule during random and blocked practice. Consistent with the contextual interference effect, the blocked practice group produced lower errors in acquisition, but the random practice group outperformed the blocked practice group in both retention and transfer. In contrast, faded feedback did not have a beneficial effect on learning and degraded learning when provided during blocked practice. While the results were consistent with previous findings of random and blocked practice, they were not consistent with previous findings of reduced feedback frequencies.     

How information guides movement: intercepting curved free kicks in soccer

Previous studies have shown that balls subjected to spin induce large errors in perceptual judgments ( [Craig et al., 2006] and [Craig et al., 2009] ) due to the additional accelerative force that causes the ball’s flight path to deviate from a standard parabolic trajectory. A recent review however, has suggested that the findings from such experiments may be imprecise due to the decoupling of perception and action and the reliance on the ventral system (van der Kamp, Rivas, van Doorn, & Savelsbergh, 2008). The aim of this study was to present the same curved free kick trajectory simulations from the perception only studies ( [Craig et al., 2006] and [Craig et al., 2009] ) but this time allow participants to move to intercept the ball. By using immersive, interactive virtual reality technology participants were asked to control the movement of a virtual effector presented in a virtual soccer stadium so that it would make contact with a virtual soccer ball as it crossed the goal-line. As in the perception only studies the direction of spin had a significant effect on the participants’ responses with significantly fewer balls being intercepted in the spin conditions when compared to no-spin conditions. A significantly higher percentage of movement reversals for the spin conditions served to highlight the link between information specifying ball heading direction and subsequent movement. The coherence of the findings for both the perception and perception/action study are discussed in light of the dual systems model for visual processing.     

The dynamical structure of handball penalty shots as a function of target location

We used principal components analysis (PCA) to investigate variations in the dynamical structure of handball penalty shots as a factor of target location and phase of shot. Participants completed a total of 10 successful shots to each of four target locations in the handball goal. Three dimensional movement time series data were analyzed. Also, data were analyzed across three temporally distinct time windows in line with the evolving kinematic chain. Statistical analyses were undertaken to determine differences across target locations. There were no significant differences between dynamical structures as a factor of target or phase. Covariance between time evolutions as a factor of target reduced in line with the ranking of the component. When shots were analyzed as three distinct time windows, only the low time evolution covariances suggested differences between targets in any time window. Our findings show that the dynamical structure underpinning the handball penalty shot does not differ greatly across locations. However, the time evolution of principal components suggests there are some variations in dynamics which may differentiate shot direction.