The No. 1 Habit That Slowly Dulls Your Sharp Mind, By A Psychologist

The article says mental decline often comes not from neglect, but from overusing familiar, successful methods.

Research on the Einstellung effect shows that past success can narrow problem-solving, reduce deeper understanding, and slow fresh thinking.

Repeated fluency with known solutions can also inflate confidence, making people think they understand more than they do.

The takeaway: expertise can dull judgment when it prevents people from starting again and reconsidering a problem from scratch.