Intermediate stimulus
Similar to the original study, we found a correlation between the proportion of correct responses on the intermediate stimulus and peak alpha frequency from eyes-closed EEG data. We did not replicate the correlation of r = 0.4 found in the original study for pre-stimulus EEG data. With n = 20 and alpha = 0.05, the original finding yielded a statistical power of 0.56. With our sample size, the effect size needed to match this power is 0.32. Our level of correlation, r = 0.28, came close to that of the original study, but it did not reach statistical significance. The low power and effect size of both the original and current results make it difficult to draw conclusions about any true relationships regarding peak alpha frequency and the proportion of correct responses on the intermediate stimulus. The lack of stronger correlations could suggest that a potential relationship between peak alpha frequency and temporal perception may be small and only apparent for near threshold stimuli. As the intermediate stimulus onset asynchrony is designed to be observable for most participants in more than 50% of the trials, it makes sense that correlations with a potential indicator for finely tuned temporal perception may be weak or even absent, as observing this stimulus would not require extremely fast visual processing. As such, there is a higher chance for incorrect responses to be due to other factors than slower temporal processing, such as lack of attention or blinking.