Depends I'd say. Memory capacity for simple items, psychoaccoustics about a psychophysically established masking threshold etc stand practically undebated, yet one may want to know specific effect sizes.

Fair enough. I would say there is still use for them, e.g., for power estimations, but indeed that's not the classical use case of whether there is an effect to begin with.

My intuition is that this will depend on effect size though, correct? If effects are generally quite large, publication bias is less severe as an issue and a meta analysis can give quite good estimates of how big effects are?

I wasn't too sure this would work with the pupil to be honest. In hindsight, I would have collected the data in addition!
But if it works with the pupil, it will work with the eeg as well I think

Preprint available here: www.biorxiv.org/cgi/content/...

Thanks to my co-authors Romke Rouw and Casper Leenaars! And last but not least to synesthete and PhD candidate @tessiehamers.bsky.social that helped with numerous pilot versions.
Preprint out now, let's see for the paper in final version. All materials online - get in touch!

Together, synesthetes sensory reports are now backed by a physiological marker that taps right into low-level sensation: after all, the pupil is part of the sensory organ itself! 
We hope that our measure provides the tool to study synesthesia where it's most interesting: at the experience level.

More importantly, we also looked at overall pupil responses between groups: reporting a color let pupils dilate in controls (higher effort!) but not in synesthetes, whose pupils corresponded to controls not having to report anything (i.e.: it is effortless for them!). Imagery is not effortless.

Relative to colored stimuli presented on screen, this response was a couple of hundred milliseconds later. Could it be active imagery of colors in our synesthetes then? 
No. Responses were too fast for that (imagery + response latency wouldn't allow for it).

We then took the brightness of each reported color to predict the pupil response to the (physically) nothing but gray number. And indeed! Splitting by reported brightness, we found a effect in synesthetes (much less in controls): dark synesthetic color = pupil dilation, bright = pupil constriction

We tested 16 number-color synesthetes and two matched control groups. Asking for the most closely associated color per trial of presenting a digit in the screen center, synesthetes give more consistent color reports (in line with synesthesia literature).

Absolutely, reanalysis wizard he is!

I'm still waiting for you to write that package that recovers pupil size from mri recordings - gotta find a way to make all that fmri data useful ;-)