Availability of advance visual information constrains association-football goalkeeping performance during penalty kicks

A pressing concern within the literature on anticipatory perceptual-motor behaviour is the lack of clarity on the applicability of data, observed under video-simulation task constraints, to actual performance in which actions are coupled to perception, as captured during in-situ experimental conditions. We developed an in-situ experimental paradigm which manipulated the duration of anticipatory visual information from a penalty taker's actions to examine experienced goalkeepers' vulnerability to deception for the penalty kick in association football. Irrespective of the penalty taker's kick strategy, goalkeepers initiated movement responses earlier across consecutively earlier presentation points. Overall goalkeeping performance was better in non-deception trials than in deception conditions. In deception trials, the kinematic information presented up until the penalty taker initiated his/her kicking action had a negative effect on goalkeepers' performance. It is concluded that goalkeepers are likely to benefit from not anticipating a penalty taker's performance outcome based on information from the run-up, in preference to later information that emerges just before the initiation of the penalty taker's kicking action.     

Manipulating informational constraints shapes movement reorganization in interceptive actions

Movement organization of cricket batters' actions was analyzed under three distinct experimental task constraints: a representative condition of a practice context in which the batters batted against a "live" bowler, a ball projection machine, and a near life-size video simulation of a bowler. Results showed that each distinct set of task constraints led to significant variations in the patterns of movement control. Removal of advanced information sources from a bowler's actions when the batters faced the ball projection machine caused significant delays in movement initiation, resulting in reduced peak bat swing velocities and a reduction in the quality of bat-ball contact, when compared with batting against a "live" bowler. When responding to a two-dimensional video simulation, batters were able to use information from the bowlers' action, enabling fidelity of initial behavioral responses consistent with the task of batting against a "live" bowler. However, without interceptive task requirements or actual ball flight information, significant variations in downswing initiation timing and peak bat velocities were demonstrated. Findings stress the need for representative experimental and learning designs in fast ball sports for developing performers.     

Structural Organization of Practice: Effects of Practicing Under Different Informational Constraints on the Acquisition of One-Handed Catching Skill

The question addressed in this study was the effects of the manipulation of the informational constraints of practice conditions on the acquisition of one-handed catching skill. Three groups of poor catchers (8 participants per group) practiced in either a normal-light, ball-only, or interspersed ball-only and normal-light condition (N = 450 trials). All groups exhibited a significant improvement in the number of catches and catching score and a reduction in the number of misses by the end of practice. The structural organization of the practice conditions had a significant effect on catching performance. Practicing in the interspersed condition had a positive residual effect on subjects' performance in normal light. Similarly, there was a positive residual effect of practicing in the ball-only and the interspersed conditions on subjects' normal-light, posttest performance. The findings are interpreted as support for the argument that practicing under varying informational constraints can benefit skill acquisition by directing the subjects' search toward relevant sources of information.     

Ecological Validity,Representative Design,and Correspondence Between Experimental Task Constraints and Behavioral Setting: Comment on Rogers,Kadar, and Costall (2005)

More than 20 years ago, Swenson (1988) Swenson, R. 1988. Emergence and the principle of maximum entropy production: Multi-level system theory, evolution, and non-equilibrium thermodynamics.. Proceedings of the 32nd annual meeting of the International Society for General Systems Research, 32: 32 [Google Scholar] proposed and elaborated the Law of Maximum Entropy Production (LMEP) as the missing piece of physical or universal law that would account for the ubiquitous and opportunistic transformation from disordered, or less ordered, to more highly ordered states. Given Boltzmann's (1974) Boltzmann, L. 1974. “The second law of thermodynamics”. In Theoretical physics and philosophical problems, Edited by: Bush, S. G. Boston: Reidel. (Original work published 1886) [Google Scholar] interpretation, the Second Law of Thermodynamics has generally been interpreted as a “law of disorder.” Schrödinger (1945) Schrodinger, E. 1945. What is life?, New York: Macmillan.  [Google Scholar] and Bertalanffy (1952) had shown, however, that the Second Law, viewed from the classical perspective of Clausius (1865) Clausius, R. 1865. Ueber verschiedene fur die anwendung bequeme formen der haupt gleichungen der mechanischen warmtheorie.. Annalen der Phys. und Chem., 7: 389–400.  [Google Scholar] and Thomson (1852) Thomson, W. 1852. On the universal tendency in nature to the dissipation of mechanical energy. Philosophical Magazine and Journal of Science, 4: 304–306. [Taylor &; Francis Online] , [Google Scholar], was not anathema to order. Ordered flow, including life, was permissible as long as it produced enough entropy to compensate for its own internal entropy reduction. The central problem remained, however: If the spontaneous production of order was “infinitely improbable,” as Boltzmann had surmised, then why were ordered systems such a fundamental and characteristic property of the visible world? LMEP provided the answer: Order production is inexorable because order produces entropy faster than disorder. In Swenson (1989d) Swenson, R. 1989d. Gauss-in-a-box: Nailing down the first principles of action. Perceiving Acting Workshop Review, 5: 60–63. (Technical Report of the Center for the Ecological Study of Perception and Action) [Google Scholar], LMEP was given expression as a precise law that could be demonstrated in falsifiable, experimental, physical terms. In Swenson and Turvey (1991) Swenson, R. 1991a. “End-directed physics and evolutionary ordering: Obviating the problem of the population of one”. In The cybernetics of complex systems: Self-organization, evolution, and social change, Edited by: Geyer, F. 41–60. Salinas, CA: Intersystems Publications.  [Google Scholar], LMEP was tied explicitly to the progressive emergence of living things with their perception–action capabilities.     

Exploring risk and protective mechanisms associated with HIV infection among adolescents in South Africa

This study explored South African adolescents’ perceived risk and protection for HIV infection. Adolescents (N=28) with a mean age of 14.6 years receiving mental health care participated in Focus Group Discussions (FGDs) to engage in an in-depth exploration of their perceived risk and protective mechanisms for HIV prevention. The data were analysed using thematic content analysis. Themes that emerged from the FGDs associated with risk for HIV infection were: Alcohol and illicit drug use; Non-condom use; Prostitution and risky sexual activity with multiple partners; and Non-disclosure of HIV status. Themes that emerged as protective mechanisms included: HIV knowledge and appropriate HIV risk reducing behaviour; and Proactive parental attitudes and behaviour. These findings highlight the importance of ascertaining the perceptions of adolescents about risk and protection from HIV infection in order to inform future programs for HIV prevention among adolescents.     

Catching With Both Hands: An Evaluation of Neural Cross-Talk and Coordinative Structure Models of Bimanual Coordination

Kelso, Southard, and Goodman (1979) and Marteniuk and MacKenzie (1980) have each proposed a different theoretical model for bimanual coordination. In the model of Kelso et al., a close temporal relationship between the hands in a bimanual task is predicted, even when each hand is required to move different distances. In Marteniuk and MacKenzie's model, separate motor commands are issued so that each limb will arrive simultaneously at the specified movement endpoint, leading to low temporal associations between limbs. In most previous work on bimanual coordination, manual aiming tasks with differing constraints have been used by subjects in individual studies. In this study, the usefulness of existing models for predicting performance in a real-world catching task in which the required movement pattern was constrained by ball flight characteristics was examined. Eleven university students caught tennis balls with both hands in the following 3 conditions: Condition 1. Ball projected to the right shoulder area (left hand moved a greater distance than the right); Condition 2. Ball projected to center of the chest area, (both hands moved same distance); and Condition 3. Ball projected to left shoulder area (right hand moved a greater distance). Kinematic data (time to peak velocity, movement initiation time) indicating significant cross-correlations between the left and right limbs in all 3 conditions concurred with the data of Kelso et al. (1979) on manual aiming. Timing appeared to be an essential variable coordinating bimanual interceptive actions. Although the limbs moved at different speeds when each was required to move different distances, times to peak velocity showed strong associations, suggesting the presence of a coordinative structure.     

A Preliminary Investigation of Body Dissatisfaction and Eating Disorder Symptomatology with Bisexual Individuals

Body dissatisfaction and eating disorder symptomatology were examined in bisexual individuals (n?=?139 women, n?=?37 men) and compared to lesbian/gay (n?=?51 women, n?=?96 men) and heterosexual individuals (n?=?82 women, n?=?34 men) in a U.S. online sample. Age, body mass index (BMI), income, and exercise frequency served as covariates. MANCOVA results showed a significant gender by sexual orientation interaction and significant main effects of gender and sexuality. Univariate tests were used to explore multivariate results. ANCOVA results for body dissatisfaction showed a significant gender by sexual orientation interaction. Post-hoc comparisons revealed higher levels of body dissatisfaction among all groups compared to heterosexual men. ANCOVA results for eating disorder symptomatology showed a significant main effect of sexual orientation. Post-hoc comparisons revealed higher levels of eating disorder symptoms among bisexual compared to heterosexual individuals. For bisexual men, gay community involvement, maladaptive social comparison, drive for muscularity, self-esteem, gender role orientation, and body dissatisfaction were explored as predictors of eating disorder symptomatology while controlling for age, BMI, exercise frequency, and income in a hierarchical regression analysis. The same factors, minus body dissatisfaction, were explored as predictors of body dissatisfaction in bisexual men. For bisexual women, similar factors, with the exception of drive for muscularity, were explored. Drive for muscularity predicted body dissatisfaction and exercise frequency predicted eating disorder symptomatology in bisexual men. BMI and self-esteem predicted body dissatisfaction in bisexual women; gay community involvement and body dissatisfaction predicted eating disorder symptomatology.