Stewart, Cooper and Moulding investigate adult metacognition development, specifically comparing pre-service teachers and practicing teachers. They used the Metacognitive Awareness Inventory and found that metacognition improves significantly with age and with years of teaching experience, but not with gender or level of teaching (Pre-K though post-secondary ed levels).

Stewart, P. W., Cooper. S. S., & Moulding, L. R. (2007). Metacognitive development in professional educators. The Researcher, 21(1), 32-40.