The Effects of Placebo on Reaction Time During Movement Preparation and Execution: A Double-Blind Placebo-Controlled Experimental Study

Abstract Purpose: This study aimed to investigate the specific effects of the placebo effect on reaction time during the movement preparation and execution phases, providing theoretical and practical insights for psychological intervention strategies in sports. Methods: A double-blind placebo-controlled experimental design was employed with 65 sports science students assigned to three groups based on self-perceived allocation: control (0.09% saline), low-dose (low-intensity placebo), and high-dose (high-intensity placebo). A high-precision reaction timer (±1 ms) recorded the preparation phase (auditory cue to hand release) and execution phase (hand release to re-press), complemented by heart rate monitoring and subjective questionnaires. Results: (1) The preparation phase dominated total reaction time (79%, M= 320 ± 45 ms), while the execution phase accounted for 21% (M = 85 ± 12 ms); (2) The self-perceived high-dose group exhibited significantly shorter execution phase times (P < 0.05); (3) The “excited” subgroup showed a significant reduction in preparation phase time compared to baseline (P< 0.01); (4) No significant placebo effects were observed on heart rate metrics. Conclusion: The placebo effect effectively shortens movement execution time by modulating cognitive expectations, while its impact on the preparation phase is mediated by subjective arousal states. These findings underscore the value of placebo-driven interventions in enhancing athletes’ reaction efficiency, offering novel perspectives for psychological training in sports. Trial registration: "An Empirical Analysis of the Impact of Placebo on Reaction Time (Preparation Stage and Action Stage) Based on a Double-blind Placebo Experiment", Current Controlled Trials ChiCTR2500105166 (registration date: June 30, 2025)