‘The More the Trials, the Stronger the Effect’: Fact or Myth? Evidence from Classical Experimental Psychology Paradigms
In cognitive sciences, behavioral studies often assume that increasing the number of trials improves the precision and magnitude of observed effects, enhancing the likelihood of detecting the effect of interest. This study tests this assumption by examining the performance of N participants across three widely used experimental paradigms (Simon effect, SNARC effect, Task Switching) with a high number of trials (>400). Surprisingly, our findings reveal that precision is not directly proportional to the number of trials. Instead, each paradigm shows a task-specific suboptimal precision point, beyond which additional trials do not improve statistical estimates and effect sizes. These results challenge the conventional notion that "more trials yield stronger effects" and highlight that excessive trial counts can be counterproductive. We discuss the implications of these findings for experimental design and data analysis in cognitive research, emphasizing the importance of optimizing trial numbers for robust and efficient outcomes.