The paddle effect on speed perception: A multilevel Bayesian meta-analysis

The paddle effect is considered one of the most robust phenomena in action-specific perception. In computer game-based Pong tasks, participants perceive targets as moving more slowly when using a larger paddle compared to a smaller one. We employed multilevel Bayesian modeling to conduct the first meta-analysis of this literature. A systematic search identified 26 independent studies from 13 articles, with a total sample size of N = 542. Results provided extreme evidence for the existence of an overall paddle effect, Hedges' g = 0.80, 95% CrI [0.71, 0.88]. Furthermore, Bayesian meta-regression analyses indicated that the effect was not moderated by experimental paradigms or measures, supporting its methodological robustness. The present meta-analysis provides the first quantitative synthesis of evidence for the paddle effect and establishes a foundation for its continued characterization in future research. In accordance with open science practices, the data, R code, and Supplementary Materials are available at the Open Science Framework ( https://osf.io/fxvbh/overview?view_only=a636518ac0f747eab10780f0e70f1e2d ).