Are there placebo or nocebo effects in balancing performance?

Area of Science:

• Motor control and rehabilitation science
• Psychology and behavioral medicine

Background:

• Placebo and nocebo effects, driven by expectations, can influence perceived and actual physical performance.
• Understanding their impact on postural stability is crucial for physical rehabilitation and individuals with motion instability.

Purpose of the Study:

• To investigate whether postural stability is susceptible to placebo and nocebo effects.
• To examine the influence of expectations on both actual and perceived postural performance.

Main Methods:

• Randomly assigned 78 participants to placebo, nocebo, or control groups, applying a sham cream with varied instructions.
• Assessed postural stability using a modified clinical test (including sensory interaction tests) before and after the intervention.
• Measured expectations, perceived performance, anxiety, optimism, and other psychological variables via questionnaires and visual analog scales.

Main Results:

• The intervention did not significantly alter actual postural stability test performances.
• Neither experimental manipulation nor psychological variables impacted actual or perceived performance.
• A strong association was found between expectation and perceived performance (ϱ = 0.627, p < 0.001).

Conclusions:

• Postural stability appears not to be directly influenced by placebo or nocebo effects.
• A dissociation exists between objective and subjective performance, where expectations affect perceived but not actual balance.
• These findings highlight the potential of expectations to enhance motivation in rehabilitation settings despite not altering objective outcomes.