For nearly a century, rhythmic patterns in electrical brain activity have been of major interest in neuroscience and electrophysiology, but much remains to be discovered about their causal contribution to cognition and behaviour. Low-frequency oscillations in the alpha band (~8-13 Hz) have been suggested to facilitate the organisation and delivery of visual information to higher-level systems, including those involved in perception and decision-making. If so, visual perception should also operate in cycles that are synchronous with – and determined by – the phase of ongoing low-frequency oscillatory activity.

 

In this #EEGManyLabs study, Ruzzoli et al. (2023) propose a large-scale, multi-lab investigation (9 labs; N=315 human participants) of the relationship between the phase of alpha oscillations and visual perception. The authors focus in particular on replicating a formative study by Mathewson et al. (2009) which reported that during high-amplitude alpha fluctuations, stimulus visibility depended on the time the stimulus was presented relative to the phase of the pre-stimulus alpha activity. In addition, the amplitude of visual evoked potentials recorded with EEG was larger when the target was presented at peaks in pre-stimulus alpha. To explain their findings, Mathewson proposed an influential pulsed inhibition hypothesis in which low alpha power boosts both cortical excitability and stimulus processing (and hence perception), while high alpha power makes stimulus processing dependent on the phase during the alpha cycle at which the stimulus is presented.

 

In the first of (up to) two studies, the authors will seek to directly replicate the key finding of Mathewson et al: that when alpha power is high, the oscillatory phase determines perceptual performance and event-related electrophysiological correlates in a masked visual detection task. Specifically, (a) alpha oscillations are predicted to modulate the probability of perceiving a target stimulus within a single oscillatory cycle, with detection rate associated with separated (and potentially opposite) phase angles, and (b) alpha phase at the onset of the stimulus should drive electrophysiological correlates of stimulus processing (including the amplitude and/or latency of the N1 ERP component).

 

Provided the results of this first study do not conclusively disconfirm these hypotheses, the authors will then conduct a follow-up study in which the temporal predictability of the target onset (in relation to a fixation stimulus) is reduced to test the more severe hypothesis that the observed correlations between alpha phase and perception are linked directly to ongoing oscillations, independent of temporal expectations.

 

The Stage 1 manuscript was evaluated over two rounds of in-depth review. Based on detailed responses to the reviewers' comments, the recommender judged that the manuscript met the Stage 1 criteria and therefore awarded in-principle acceptance (IPA).

 

URL to the preregistered Stage 1 protocol: https://osf.io/scqj8​ (under temporary private embargo)

 

Level of bias control achieved: Level 6. No part of the data or evidence that will be used to answer the research question yet exists and no part will be generated until after IPA. 

 

 
References

 

1. Ruzzoli, M., Cuello, M. T., Molinaro, N., Benwell, C. S. Y., Berkowitz, D., Brignani, D., Falciati, L., Harris, A. M., Keitel, C., Kopčanová, M., Madan, C. R., Mathewson, K., Mishra, S., Morucci, P., Myers, N., Nannetti, F., Nara, S., Pérez-Navarro, J., Ro, T., Schaworonkow, N., Snyder, J. S., Soto-Faraco, S., Srinivasan, N., Trübutschek, D., Zazio, A., Mushtaq, F., Pavlov, Y. G., & Veniero, D. (2023). In principle acceptance of Version 2 by Peer Community in Registered Reports. https://osf.io/scqj8​

 

2. Mathewson, K. E., Gratton, G., Fabiani, M., Beck, D. M., & Ro, T. (2009). To see or not to see: prestimulus α phase predicts visual awareness. Journal of Neuroscience, 29, 2725-2732. https://doi.org/10.1523/JNEUROSCI.3963-08.2009