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.