Two types of ball-effector interaction and their relative contribution to soccer kicking

The study attempts a closer examination of the ball-foot interaction at the instant of soccer kicking using high speed videotaping. This allows a detailed biomechanical analysis of the collision. A central question is whether the ball-foot interaction can be modeled as an elastic impact, or as a mixture of ‘impact-like’ and ‘throwing-like’ patterns. The findings prove that the theory of conservation of momentum alone is not adequate for modeling kicking: additional momentum and mechanical energy is supplied to the system during the collision phase because of the muscle work. This is due to the relatively long duration of collision (about 16 ms) and the large ball-foot displacement (about 26.0 cm). More than 50% of the ball's speed and at least 30% of its kinetic energy is imparted to the ball without any contribution of the potential energy of the ball deformation.     

The basis of behavioral momentum in the nonlinearity of strength

The persistence of operant responding in the context of distractors and opposing forces is of central importance to the success of behavioral interventions. It has been successfully analyzed with Behavioral Momentum Theory. Key data from the research inspired by that theory are reanalyzed in terms of more molecular behavioral mechanisms: the demotivational effects of disruptors, and their differential impacts on the target response and other responses that interact with them. Behavioral momentum is regrounded as a nonlinear effect of motivation and reinforcement rate on response probability and persistence. When response probabilities are high, more energy is required to further increase or to decrease them than when they are low. Classic Behavioral Momentum Theory effects are reproduced with this account. Finally, it is shown how the new account involving motivation and competition is closely related to the metaphor of force and action that is at the core of Behavioral Momentum Theory.     

Operational momentum in large-number addition and subtraction by 9-month-olds

Recent studies on nonsymbolic arithmetic have illustrated that under conditions that prevent exact calculation, adults display a systematic tendency to overestimate the answers to addition problems and underestimate the answers to subtraction problems. It has been suggested that this operational momentum results from exposure to a culture-specific practice of representing numbers spatially; alternatively, the mind may represent numbers in spatial terms from early in development. In the current study, we asked whether operational momentum is present during infancy, prior to exposure to culture-specific representations of numbers. Infants (9-month-olds) were shown videos of events involving the addition or subtraction of objects with three different types of outcomes: numerically correct, too large, and too small. Infants looked significantly longer only at those incorrect outcomes that violated the momentum of the arithmetic operation (i.e., at too-large outcomes in subtraction events and too-small outcomes in addition events). The presence of operational momentum during infancy indicates developmental continuity in the underlying mechanisms used when operating over numerical representations.     

Do not drop your gloves: “Winning” a fight in the National Hockey League does not improve chances to win the game

Sanctioned fighting has played an integral role in the National Hockey League (NHL) since its early days. Proponents argue that this practice helps teams win games. More specifically, they contend that when a player triumphs decisively in a fight, the outcome creates momentum or a spark for his teammates and thus increases his team’s odds of victory. We used on-line fans’ voting (validated by objective fight data) to assess fight outcome and demonstrated that “winning” the fight did not lead to winning the game when the score was tied. Additionally, in contrast with the “change in momentum” hypothesis, prevailing in a fight did not sway game outcome when the home or away team was one goal behind early enough in the game. Lastly, prevailing in a fight was not associated with scoring the next goal. We discuss the results in light of the strong conviction held by NHL players that fighting boosts momentum and explain possible mechanisms working to preserve this false belief.     

Does success breed success? An investigation of momentum in elite recurve archery

We investigate the existence of momentum or the “hot hand” phenomenon in recurve archery, in which archers have three shots per set. We collected the performance of archers along with the control variable (player difference) and game data (set score difference, shooting order and game type). We set out to compare the outcome (bullseye, 10 points, probability) and performance (scores of the third shot) in a range of cases with the previous two shots. The most obvious finding to emerge from this study is the powerful evidence for positive momentum in recurve archery. The key finding that hitting the bullseye creates momentum and momentum leads to better performance has been confirmed as the “success breeds success” mechanism. Furthermore, the performance of the third shot is influenced by competitive ability and match importance (Olympic Games or not).