Understanding the relationship between alpha oscillations and visual perception

The authors have addressed all my concerns very well. I have only one suggestion:

The authors say they will not concatenate the data across the labs in order to look at variability across the labs. I’m not sure how concatenating and not concatenating in separate analyses might be mutually exclusive. Wouldn’t the most powerful test be based on the largest available sample and look at differences between labs separately? Such a concatenation might help delineate interpretations in the event of non-significant outcomes and address the concern well voiced in the introduction that if there is an effect, it might be much smaller than previously reported. Of course, such an analysis could be explored in a non-pre-registered way, which would mean no changes to the current manuscript, but I would encourage the authors to include it and integrate it now, possibly as a secondary analysis, as I think such a test has the potential to be informative.

The Authors have satisfactorily​ addressed all my concerns. Good luck for this important replication project!

The authors have responded to my queries, which were only minor, and I how no furter comments. Happy for this interesting study to now go ahead. Best of luck!  

Review for To see, not to see or when to see: An #EEGManyLabs replication study with a twist

This is one of the best pieces of work I have been asked to review! It aims to replicate an important study with foundational implications for influential theories of oscillatory brain function. There have been previous replication attempts in this area, including a Registered Report, but I am not aware of such a multi-lab attempt with potentially such high power (but see point 4 below). The outcome of this, I expect, will be of great interest to the related field.

Below I list some suggestions for adjustments in order of appearance in the manuscript, none of which I see as fundamentally critical.

1. Title: would it be possible for the title to be a bit more specific and informative? Something along the lines of ‘Testing the replicability of alpha phase determining visual perception’. I realise that’s not as catchy, but I found the current title a little vague.

Introduction:

2. The third sentence assumes subjective experience is a continuous flow, but phenomenology suggests this is not straightforwardly the case (see e.g., Husserl, The Phenomenology of Internal Time-Consciousness, or Busch and VanRullen, 2014, Is visual perception like a continuous flow or a series of snapshots? In Subjective Time, MIT Press, or Dainton, 2010/232023, Stanford Encyclopaedia of Philosophy, Temporal Consciousness ). This could be simply resolved by losing the first part of that sentence.

3. In the hypothesis at the end of the introduction, I thought the statement under a negative finding that “there is no evidence for visual perception to operate in cycles” was a little strong, and perhaps should be rephrased to refer to this study's evidence. This also relates to the point 9 below. Relatedly, I thought it would be potentially more informative if the decision criteria at the end of the introduction (which seems primary) were based on the outcome of the Bayesian analysis rather than the frequentist statistics.

Methods:

4. I found the first and second sentences of the participants section a little ambiguous. It could be read that the 7 labs will collectively provide a 35 participant data set, i.e., 5 each, OR, each lab would aim to contribute a 35 participant data set. My confusion was not helped by other sections seeming to imply that both the full data set had n=35 (e.g., “final sample size (N=35)”), and each lab is to produce a complete data set (e.g., “compute effect sizes (Cohen’s d) for each individual lab”). If it is the former, and given the reasons well specified in the introduction for effect sizes reported by Mathewson et al., being larger than we might expect in replication, then I do not think the study as it stands should be described as “high-powered”. If there is a real effect but it is smaller, as the authors suggest is likely, the study would be underpowered. Would it be possible to recalculate power estimates based on smaller effect sizes? Perhaps, based on the estimates of VanRullen et al., 2016 described in the introduction? I appreciate the intention behind the use of the Mathewson et al., effect sizes, but if they are used, I suggest explicitly describing the limitations in interpreting a negative outcome (also see point 9).

If, however, each lab is to contribute a 35-participant data set, then great, and I think this should be made clearer and the total minimum n should be stated. It might also help if the smallest effect size reliably detectable was stated. Inclusion of such should be informative either way. I also wondered whether a simpler concatenation of the data across labs might complement the meta-analytic approach but be slightly more powerful. I also thought it might be possible to combine evidence across labs more efficiently by taking advantage of Bayes Factors being transitive (Morey and Rouder, Psychological Methods, 2011).

5. I didn’t see the need to restrict the age of participants to a 12-year range.

6. Stimuli and procedure. I thought there should be a sentence qualifying the timings as approximate, or specifying two sets of timings, as the refresh rates of the monitors used across the different labs would mean these exact timings cannot be followed by all labs.

7. The sentence “The experimental session counts 16 blocks of 72 trials each”, should that be “The experimental sessions consist of 16 blocks of 72 trials each”?

8. Should an impedance target be prescribed? I understand this can be equipment-dependent, but then maybe it could be lab-specific.

9. I would have liked to see more weight given to adjudication between support for null vs. lack of evidence in case of a negative finding in the main text. I think differentiating between these two potential outcomes could be important information for the field. I understand that the Bayesian meta-analytic approach offers the potential to do this, so I was wondering whether the Bayesian analyses could receive a greater emphasis in terms of decision criteria. For example, at the end of the introduction. This might mean using Bayesian equivalents for the primary t-tests (which can be derived from T statistics) and recalculating the sample size estimation based on Bayesian simulations, but in my experience, the outcome invariably aligns between Bayesian and frequentist estimations. Alternatively, frequentist statistics can assess equivalence (Lakens et al,. 2018, AMPPS). This relates to point 4 where to fairly assess equivalence, a smaller expected effect size may be required.

10. Related to the above point and based on the expectation of small effects described in the introduction, I thought the prior applied in the Bayesian analyses should probably reflect this aspect of the hypothesis and be smaller than the default 0.707 scaling factor (see Dienes, 2011, Perspective on Psychological Science).

11. Table 1 describes decision criteria based on p<0.05, whereas the text describes p<0.02 criteria (also true in the final table). Can this be checked or reasons for the discrepancy given? Also, I did not find the description of Hp b1 in this table very easy to understand.

12. Table 2 and the final table seem to repeat much of the same information, I realise the final one conforms to guidelines, but I still wondered whether they could be integrated. I also thought the final table would benefit from basing criteria on Bayesian tests to more straightforwardly differentiate between negative and inconclusive outcomes, and this might help align the tables.

This registered report describes a large replication project under the initiative #EEGManyLabs. The aim for this report is to describe a replication of the study by Mathewson et al. (2009), which was among the first evidence showing that the visibility of a visual target stimulus depended on the phase of prestimulus alpha phase.

I find this this multi-labs project very interesting. The report is well written and clearly describe all the details of the replication study that will be conducted.

I have only a couple of observations that relate to the declared intent of performing a second study, conditioned to the results of the first one, where the Authors would like to test whether temporal expectation plays a role in the relationship between stimulus detection and ongoing alpha. The motivation behind the 2nd study is clear: i.e., if visual perception operates in cycles, any influence of pre-stimulus alpha phase on behavioural and/or neurophysiological measures should be valid even when less (or no) temporal expectation is present. However, I would suggest the Authors to consider embracing the following observations:

1) I think that sometimes the description of the rationale Study 2 is overly simplistic. It is true that in Study 1 subjects will have strong temporal expectation becuase of the very short and fixed inter-stimulus interval (ISI) employed, but such expectation will be very likely to be present also in Study 2, altough in an attenuated form. This should be more clearly stated.

2) I invite the Authors to consider that, in case Study 1 will be succesfully replicated, temporal expectation is only one out of the different aspects that differentiate the two studies. For example, the evoked response and the concomitant 'phase reset' created by the appearence/disappearence of the fixation cross is likely to be more influential in Study 1 than in Study 2, becuase of the increased temporal distance between events present in Study 2. How will the Authors take into account this factor in Study 2 to be sure about their conclusion on the role of temporal expectation? This should be better clarified.

This registered report aims to replicate the effects observed in Mathewson et al (2009) in study 1 which has a fixed ISI. If the results are replicated, then a variable ISI will be included in a study 2. The original Mathewson et al. study has some limitations in the fixed ISI design, which are covered nicely in the intro, and it also has some issues with the sample size used. Or rather, the lack of estimating sample size, which we all did back in 2009. Thus, it is a good study to replicate in this #EEGManyLabs. The manuscript is nicely written and its clear. I only have one main point and a couple of minor things to clarify.

The prediction is that if temporal expectation may be present in study 1 with the fixed ISI but not in Study 2 which includes a variable ISI. I think one thing to consider is any potential influence of the foreperiod effect/hazard function which may be present in Study 2. That is, there is some type of temporal expectation (the effect of time) in Study 2 which is not there in Study 1. So the question is whether you have considered if the foreperiod/hazard effect can influence the results? Would be good if you can add something regarding this.

Minor

Why pick Pz and Fz as the analysis electrodes? I get that these were the ones used in the original paper, but in that paper they also used Oz and show an effect on P1/P2 components.

Quality checks: Can you please add a bit more description of what “target only trials larger than 0dB…” As the timing is crucial to this study and finding effects (if they are there) then the checks are important. You don’t want to find yourself in a situation where a lab fails to replicate due to poor timing, not due to the effect. The relatively high refresh rate will go some way ensure stim presentation is accurate, but of course other things can cause delay. If the results are different across labs then you might want to check with e.g. a photo diode that any results are not due to poor timing. Just to rule that out.

Alexander Jones