Brief expressions that flit across a subject's face in as short a time as it takes to blink an eye are called adaptors.

Question

Quizplus · Accepted Answer

These brief expressions are called microexpressions, not adaptors. Microexpressions are involuntary and reveal a person's true emotions, while adaptors are behaviors often used to manage or adapt to a specific situation or stress, such as fidgeting or adjusting one's clothing.

Brief Expressions That Flit Across a Subject's Face in as Short