How do women really know if they are having an orgasm?

Dr Nicole Prause is challenging bias against sexual research to unravel apparent discrepancies between physical signs and what women said they experienced

In the nascent field of orgasm research, much of the data relies on subjects self-reporting, and in men, there's some pretty clear physiological feedback in the form of ejaculation.

But how do women know for sure if they are climaxing? What if the sensation they have associated with climax is actually one of the the early foothills of arousal? And how does a woman know if she has had an orgasm?