The role of visual error and reward feedback in learning to aim to an optimal movement endpoint.

When presented with a target circle horizontally overlapped by a penalty circle, participants initially aim closer to the penalty circle than optimal and with experience and feedback shift their endpoint horizontally to the optimal endpoint. Our purpose was to determine whether solely reward feedback or reward feedback in combination with visual error feedback of the movement and final movement endpoint is necessary for participants to learn to aim to the optimal endpoint. Participants received money for hitting the target but lost money for hitting the penalty region. In a critical No Feedback group, the target/penalty configuration would disappear on movement initiation, but participants were told the number of points received or lost after each trial. Similar to groups receiving various amounts of visual error feedback (target never disappeared, or reappeared upon screen contact), participants in the No Feedback group shifted the endpoint horizontally with experience, but they vertically undershot the horizontal meridian that contained the optimal endpoint. The region of the vertical undershoot, although suboptimal, was associated with less variance in the value of the expected outcomes. We suggest that reward feedback encourages participants to aim toward this less risky region, whereas receiving full visual error feedback leads participants to aim to the more advantageous horizontal meridian. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Examining Changes to Center of Pressure During the First Trials of Wii Gameplay.

OBJECTIVE: Use of the Nintendo Wii™ as a balance assessment and rehabilitation tool continues to grow. One advantage of the Wii is that games can serve as a virtual reality training tool; however, a disadvantage of the Wii is the human-machine interface and the learning effect over multiple trials. The purpose of this study was to assess changes in postural control during Wii gameplay over a series of trials in novice players. MATERIALS AND METHODS: Thirty-one university athletes (aged 18-25 years) completed four trials of the Nintendo Wii Fit™ soccer heading (SH) balance game. Center of pressure (COP) was calculated in the anterior-posterior (AP) and medial-lateral (ML) directions for each 70-second time trial at 1000 Hz. COP was assessed using six linear and two nonlinear measures. Repeated measures analysis of variances compared COP measures over the four trials. RESULTS: Significant differences in COP magnitude and velocity were found between trials 1 and 2 in the ML direction. No significant effects of trial were found in the AP direction. In contrast, a measure of the overall area of COP using an ellipse method revealed a significant reduction to COP area between trials 3 and 4. No significant differences between trials were observed in nonlinear measures. CONCLUSIONS: These results demonstrate how magnitude and velocity measures of COP control stabilize after the first trial of Wii SH game play in novice young adults. As Wii rehabilitation focuses on individuals with balance difficulties, an important consideration when using the game as an assessment tool is that more than four trials may be required to capture learning in these populations. In addition, contrasting results from ellipse measurement methods point to the use of multiple measures for robust description of COP behavior. This work provides understanding of normative postural control responses with further research in clinical populations needed.