The relationship between individual alpha frequency and time perception: Testing the internal clock versus the sampling rate hypothesis

Perceiving the duration of events is a fundamental ability for everyday life. Traditional research has focused on the role of alpha oscillations as an endogenous pacemaker for the human internal clock, yet there is limited evidence supporting this idea. An alternative hypothesis proposes that alpha oscillations may underlie a sampling mechanism, where higher alpha frequencies correspond to increased information sampling, resulting in more accurate temporal judgments. In this study, we tested the internal clock versus sampling rate hypothesis by examining the relationship between Individual Alpha Frequency (IAF) and fine-grained time perception. Using resting Electroencephalography (EEG) and Signal Detection Theory (SDT), fifty healthy volunteers performed a time-discrimination task with 100 and 500 msec standard durations. Our results demonstrate that temporal sensitivity (d') but not temporal bias (c) is influenced by IAF, with higher IAF leading to more accurate time estimates (higher d'). The correlations were observed over frontocentral topographies consistent with previous reports of neural networks involved in time processing and were most pronounced at 100 msec relative to 500 msec, likely due to fluctuations in IAF across multiple cycles. In conclusion, our findings support the relationship between IAF and temporal sensitivity. These results challenge the pacemaker hypothesis and instead suggest a distributed mechanism where alpha oscillations enhance the precision of temporal sampling. Our study adds to the growing body of evidence highlighting the role of IAF in sensory sampling as a generative mechanism for temporal sensitivity as opposed to subjective time perception.