How shooting distance affects technique (and the transition between attractor states)

The technique that you tend to adopt in specific situations is referred to as an attractor state (or a coordination tendency). For instance, lets say you shoot a basketball 10 times. While the movements for each shot will be slightly different from one another, there will likely be a common movement pattern that emerges. This is an attractor state.

A key focus of coordination research is to identify attractor states and understand the factors that cause attractor states to change.

Robert Rein and colleagues investigated whether manipulating distance from the ring caused basketball players to transition between different attractor states when shooting.

The significance of this study was in the type of skill investigated – a discrete skill as opposed to a continuous skill. You see, when examining coordination, it is far easier to identify attractor states in continuous skills, such as walking. Very few researchers have attempted to analyse discrete skills, even though they are common to most sports.

The study

8 basketball players participated in the study. The players were a mix of semi-professional players (n =3), club level players (n = 4) and a novice (n = 1). Players were asked to shoot a basketball from different distances using a hook shot technique. The distances that the players shot from occurred in a specific order.

In one condition, players began shooting from 2 metres and gradually increased to 9 metres in 1 metre increments. In another condition, players began shooting from 9 metres and gradually reduced to 2 metres in 1 metre increments.

Three-dimensional motion cameras were set up to measure each player’s kinematics when shooting. This allowed for the assessment of attractor states.

Attractor states were identified using a cluster analysis approach (a statistical method that clusters data into groups based on how similar the data is; i.e., movement patterns that share similar kinematics were grouped together) coupled with a visual inspection of angle-angle plots (plots that show the relationship between 2 joint angles when performing a skill).

Participants were analysed individually.

Key finding

2 of the 8 participants demonstrated clear transitions between different attractor states when shooting distance changed. This means that they used two unique shooting techniques, with a different technique emerging for longer shots compared to shorter shots. One of these participants was skilled (semi-professional) and the other was a novice.

The remaining 6 participants adopted a single attractor state across all distances. In other words, a similar technique was used for the longer shots as the shorter shots. This was achieved by adapting the one attractor state to each distance.

Practical implications

Distance to the ring is an example of a control parameter that can influence transitions between attractor states when shooting a basketball. Coaches can use control parameters as a means to introduce variability into practice. This will allow players to (a) learn to adapt attractor states to new conditions and/or (b) develop new attractor states. Adapting and developing attractor states are important skills in the quest for expertise.

Reference

Rein, R., Davids, K., & Button, C. (2010). Adaptive and phase transition behavior in performance of discrete multi-articular actions by degenerate neurobiological systems. Experimental Brain Research201(2), 307-322.

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