Mixed control for perception and action: timing and error correction in rhythmic ball-bouncing

Abstract

The task of bouncing a ball on a racket was adopted as a model system for investigating the behavioral dynamics of rhythmic movement, specifically how perceptual information modulates the dynamics of action. Two experiments, with sixteen participants each, were carried out to definitively answer the following questions: How are passive stability and active stabilization combined to produce stable behavior? What informational quantities are used to actively regulate the two main components of the action-the timing of racket oscillation and the correction of errors in bounce height? We used a virtual ball-bouncing setup to simultaneously perturb gravity (g) and ball launch velocity (v b) at impact. In Experiment 1, we tested the control of racket timing by varying the ball's upward half-period t up while holding its peak height h p constant. Conversely, in Experiment 2, we tested error correction by varying h p while holding t up constant. Participants adopted a mixed control mode in which information in the ball's trajectory is used to actively stabilize behavior on a cycle-by-cycle basis, in order to keep the system within or near the passively stable region. The results reveal how these adjustments are visually controlled: the period of racket oscillation is modulated by the half-period of the ball's upward flight, and the change in racket velocity from the previous impact (via a change in racket amplitude) is governed by the error to the target.

Using task dynamics to quantify the affordances of throwing for long distance and accuracy.

“…Siegler et al, 2013;Warren & Whang, 1987). The current work in throwing extends the approach to understanding affordances in terms of dynamics as well (e.g.…”

Major Changes in a Rhythmic Ball-Bouncing Task Occur at Age 7 Years

“…Following Siegler et al [27], [28], who characterized the coupling between visual information and racket movement in adult ball bouncing, we computed the correlation R c between the duration of ball motion following the last impact of each cycle (of a trial) T up and the period T r of the cycle following this impact (Figure 1, Left). The R values of the 16 trials were converted into Z values using Fischer's Z transformation in order to enable averaging and statistical analyses.…”

“…This task, which consists in rhythmically hitting a ball in a virtual environment, was previously used in order to study the role of visual information in the control of racket motion in adults [27], [28]. Participants are instructed to manipulate a physical table tennis racket that controls a virtual racket so as to get the ball as close as possible to a target placed at a constant height.…”

“…This was expected to make this bouncing task doable for young children. Such set-ups were used in previous studies in adults in which the loss of haptic information on ball-racket impacts was not found to impair the ability to control ball bouncing [27], [28], [30], [31].…”

The effect of stereotype threat on performance of a rhythmic motor skill.

“…In contrast to the dynamic stability achieved with ball-racket impacts during the decelerating racket trajectory, hitting the ball with an accelerating trajectory produces unstable performance and errors amplify from one bounce to the next (Figure 2B,C). To compensate for such unstable performance, the novice participants can actively correct for errors by adjusting their racket trajectory to propel the ball either higher or lower than the previous bounce, based on visual information about the error (de Rugy, Wei, Müller, & Sternad, 2003; Wei et al, 2007; Siegler, Bazile, & Warren, 2013). However, with practice, participants learn to hit the ball with negative acceleration, reducing the necessity for active correction of errors (Wei et al, 2008).…”