Perceptual-Cognitive Skill

Influencing serve direction in volleyball (implicitly)

In 2007, Rich Masters, Jon van der Kamp and Rob Jackson published an article in Psychological Science revealing that the direction of a penalty kick soccer is influenced by the position of the goalkeeper. When the goalkeeper stood off-centre by the smallest of margins so that the kicker could not consciously detect the off-centre location, the kicker more often than not selected the larger side of the goals to kick towards.

Recently this was extended to the volleyball serve. In volleyball, the server selects a location on the other side of the court where they intend to serve the ball towards. Opposition players will typically stand an equal distance apart to ensure that there are no large open spaces (unless, of course, that is a specific team tactic).

However, what happens if the space between some players is slightly larger than other spaces?

Benjamin Noel and colleagues designed 2 experiments that tested whether volleyball players (1) select the larger area to serve the ball to, even if they do not consciously detect that it’s a larger area, and (2) whether the server can negate the implicit bias effect if they are instructed to pay attention to the possibility of larger areas.

Experiment 1

25 volleyball players completed a volleyball decision making task on a computer. In this task, participants assumed the role of the server. The task required participants to state whether two players on the opposition team were standing in a neutral position (all areas of equal size). If they perceived players to be standing in a neutral position, they were then asked to select where they would serve the ball to. The opposition players stood either to the left or the right of the neutral position. This created a larger space on either the left side of the court, the centre of the court, or the right side of the court. The displacements from the neutral position ranged from 0, 2, 4, 6, 8, 10, 12 and 48 cm (if projected onto a real court).

The key results were as follows:

  • More often than not, participants thought that the opposition players were standing in a neutral position when they were < 10 cm off centre.
  • When the displacement was 4 to 8 cm, participants selected the larger area to serve the ball to more often (approximately 50% vs. < 30% for the other two areas).
  • A displacement of 2 cm was seemingly too small to cause participants to select the larger open area to serve the ball.

Experiment 2

The authors wanted to discover if participants could actually detect the larger open side at displacements < 10 cm. To achieve this, participants completed the same task as Experiment 1, but were instructed to search for the larger area (rather than determine if the players were in a neutral position). Moreover, participants had to rate on a scale of 1 to 100 how confident they were in their decision. The displacements from the neutral position ranged from 0, 4, 8, 12 and 48 cm.

The key results were as follows:

  • Participants could correctly identify the larger open at better than chance at all displacements.
  • However, when the opposition players were standing 4 cm off-centre (the smallest displacement), participants reported low confidence in their decisions. This suggests that the accurate identification of the larger open space at this distance was due to implicit (sub-conscious) processes.

Implications

In sports where an opponent is directing an object towards a target (e.g., soccer penalty kick, volleyball serve), the defender can influence the direction that the object is projected by standing marginally off-centre.

However, the person projecting the object (e.g., the kicker in a soccer penalty or the server in volleyball) can negate this effect by deliberately searching for the larger open area.

Limitation – Action capabilities

In both experiments, the authors ruled out the possibility of participants having a preferred direction of serving the ball. This was achieved by assessing if there was a bias in serve direction when the opposing players were standing in a truly neutral position (0 cm displacement).

However, this assessment does not rule out the possibility that participants have a bias in where they serve the ball when actually performing the skill. For instance, on a computer task, I might be willing to the serve the ball to all locations. Conversely, when actually performing the skill, I might only be able to serve the ball to the back left corner. Hence I become biased towards serving to this location regardless of where the opponents are standing. This is an important consideration when applying this concept in practice.

Reference

Noël, B., Hüttermann, S., van der Kamp, J., & Memmert, D. (2016). Courting on the beach: How team position implicitly influences decision-making in beach volleyball serves. Journal of Cognitive Psychology, 28(7), 868-876.

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