Ten-year-old carolina loves to read and enjoys looking up the meanings of words she does not know. her teacher promises a gold star to students each time they learn a new word.

The teacher's action would undermine: Intrinsic motivation

Intrinsic motivation refers to the motivation that caused by internal rewards, such as the desire to succeed or personal principles.

Giving Gold Star is a form of external rewards and this tends to overshadow the intrinsic motivation that people have to achieve something.