Expectancy Effects Threaten the Inferential Validity of Synchrony-Prosociality Research

Area of Science:

• Social Psychology
• Behavioral Science

Background:

• Existing research suggests synchronized movement enhances prosocial behavior.
• Concerns exist that these findings may be influenced by experimenter bias and participant placebo effects.

Purpose of the Study:

• To investigate the role of expectancy effects in the purported link between synchrony and prosociality.
• To re-evaluate the evidence for synchrony-driven prosociality.

Main Methods:

• Meta-analytic review of existing studies on synchrony and prosociality.
• Analysis of control measures in published research.
• A preregistered experiment measuring participant expectancy regarding synchrony and prosociality.

Main Results:

• Many studies lack adequate controls for experimenter bias.
• Replication attempts with enhanced controls have often failed.
• Participant expectations about synchrony's effects mirrored published findings, even without actual synchrony.

Conclusions:

• Reported prosocial effects of synchrony may stem from top-down expectations (placebo and experimenter effects) rather than genuine bottom-up mechanisms.
• Future research should rigorously control for expectancy biases.