We know what stops you from thinking forever: A metacognitive perspective.

This commentary addresses omissions in De Neys's model of fast-and-slow thinking from a metacognitive perspective. We review well-established meta-reasoning monitoring (e.g., confidence) and control processes (e.g., rethinking) that explain mental effort regulation. Moreover, we point to individual, developmental, and task design considerations that affect this regulation. These core issues are completely ignored or mentioned in passing in the target article.