Effect of Normative Feedback on Balance Control and Consistency of Muscle Function with Variable Task Difficulty

The previous research on normative feedback regarding balance control has only focused on psychological indices, and physiological information on the mechanisms of normative feedback on performance in difficult tasks (those involving visual and proprioceptive sensory disturbance), especially balance tasks, is scarce. Thus, the present study was conducted to determine the effects of normative feedback on balance control and the consistency of muscle function during tasks of variable difficulty levels among novice individuals.
The present study followed a sub-experimental and laboratory based design. A total of 20 participants (mean age = 23.59, SD = 1.30 years) were randomly assigned to positive normative feedback and control groups. The experimental group participated in 160 acquisition trials (16 blocks of 10 trials each) over 4 consecutive days (40 per day). A post-test was performed after the last practice session. Participants in the positive normative feedback group received better information of their own average performance in each block of acquisition. Postural control indices and electrical activity of muscles were measured using the Biodex system and electromyography techniques using Megawin devices, respectively. Mixed ANOVA with repeated measures and covariance tests were run to evaluate between-group differences in the balance index and electromyographic findings.
The positive normative feedback group (M = 1.45 ± 0.31) outperformed the control group (M = 5.97 ± 1.24) in terms of the balance index (P = 0.004) and muscle consistency of the rectus femoris (P = 0.007) and gluteus medius (P = 0.04) while performing tasks of various difficulty levels.
As a psychological placebo, positive normative feedback acts as functional motivation to directly influence physiological changes in the level of balance control and consistency of muscle function when individuals perform difficult tasks.