This is broadly speaking not correct. If you average together a bunch of trials with variable timing, then the result can tend to wash out higher frequency comp

This is broadly speaking not correct. If you average together a bunch of trials with variable timing, then the result can tend to wash out higher frequency components (which you might not have realized were in the data), but trial averaging is not a low pass filter at all. There are some nice methods to recover temporal structure that changes across trials prior to averaging, like: https://www.sciencedirect.com/science/article/pii/S0896627319308943 https://www.sciencedirect.com/science/article/pii/S089662731...