Most damningly, the review didn't turn up dose-dependent results. If n-back works, I would expect either "more is better" or "flat gain past some minimum". In

Most damningly, the review didn't turn up dose-dependent results. If n-back works, I would expect either "more is better" or "flat gain past some minimum". Instead, the effect vs training graph is a shapeless cloud, which seems like a major warning sign.