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

Abstract

Many studies using cognitive tasks have found that stereotype threat, or concern about confirming a negative stereotype about one's group, debilitates performance. The few studies that documented similar effects on sensorimotor performance have used only relatively coarse measures to quantify performance. This study tested the effect of stereotype threat on a rhythmic ball bouncing task, where previous analyses of the task dynamics afforded more detailed quantification of the effect of threat on motor control. In this task, novices hit the ball with positive racket acceleration, indicative of unstable performance. With practice, they learn to stabilize error by changing their ball-racket impact from positive to negative acceleration. Results showed that for novices, stereotype threat potentiated hitting the ball with positive racket acceleration, leading to poorer performance of stigmatized females. However, when the threat manipulation was delivered after having acquired some skill, reflected by negative racket acceleration, the stigmatized females performed better. These findings are consistent with the mere effort account that argues that stereotype threat potentiates the most likely response on the given task. The study also demonstrates the value of identifying the control mechanisms through which stereotype threat has its effects on outcome measures.

Figure 1

Front and side view of the virtual experimental setup for ball bouncing. Participants were positioned in front of a screen and manipulated a real table tennis racket to rhythmically bounce a virtual ball to a target height in a 2D virtual environment.

Figure 2

Simulation of the ball-racket system. A: Assuming sinusoidal racket movement, the racket trajectory has a segment with positive acceleration followed by negative acceleration before its peak position. B: When the racket impacts the ball during the decelerating portion of the racket's upward motion, the ball-racket system is dynamically stable. Slightly different initial conditions all lead to the same stable ball amplitude without any changes in the racket trajectory. C: If the ball impacts the racket during the accelerating portion of the racket's upward motion, the system is unstable. Different initial conditions all lead to unstable behavior where the ball finally sticks to the racket. The only way to achieve and maintain a stable pattern is to correct for errors in the ball amplitude by a change in the racket trajectory.

Figure 3

Schematic diagram describing the mere effort account. If the prepotent response is correct, the mere effort account suggests that stereotype threat facilitates performance for stigmatized individuals. If the prepotent response is incorrect and participants do not know, performance is debilitated. However, if participants are able to recognize that their prepotent tendencies are incorrect and have the time to correct them, performance can be facilitated.

Figure 4

Time series of racket (black) and ball (gray) trajectories illustrating the dependent measures. A bounce is the event between two consecutive ball-racket impacts. Error was defined as the unsigned difference between the target height and the maximum ball amplitude at each bounce. Racket acceleration at impact was defined as the racket acceleration 25 ms before the ball-racket impact of each bounce. Ball velocity at release was defined as the velocity of ball at the instantaneous ball-racket impact of each bounce. Bounces, where the difference between the ball and racket maximum positions was below 0.25 m, referred to as stuck bounces, were excluded from the data analysis in Experiments 2 and 3.

Figure 5

Performance measures of all participants over practice in Experiment 1. A: The means of median of error of participants in all four experimental groups. B: Means of the median racket accelerations at impact for each trial across 25 trials. C: Means of lag-1 autocorrelation of release ball velocities at impact for each trial across 25 trials.

Figure 6

Mean error and racket acceleration across practice and statistical comparisons in Experiment 2. A: Participant means of median errors across 25 trials. B: Statistical comparison of error between experimental groups. Error bars represent ± 1 standard error. C: Participant means of median racket accelerations across 25 trials. D: Statistical comparison of racket acceleration between experimental groups.

Figure 7

Mean error and racket acceleration across practice and statistical comparisons in Experiment 3. Error bars represent ± 1 standard error of the mean. The Female ST group does not receive the stereotype threat manipulation until after trial 12, as marked with the vertical line. A: Participant means of median errors across 24 trials. B: Statistical comparison of error in Blocks 1 and 2 between experimental groups. C: Participant means of median racket accelerations across 24 trials. D: Statistical comparison of racket acceleration at impact in Blocks 1 and 2 between the two experimental groups.

Figure 8

Simulation of the ball-racket system with time-dependent manipulation. A: If the ball impacts the racket during the accelerating portion of the racket's upward motion, the system is unstable. B, C: When the racket impacts the ball during the decelerating portion of the racket's upward motion, the system is unstable if the racket phase is less than .05ω; otherwise, the perturbed ball-racket system is dynamically stable.