I think you're thinking of microsaccades. Saccades in general are just rapid, ballistic eye movements: they don't have to be small and they're often voluntary.

I think you're thinking of microsaccades. Saccades in general are just rapid, ballistic eye movements: they don't have to be small and they're often voluntary. You often make saccades without explicitly thinking about it, but you can countermand these and hold your eyes still when you want to.