That's Masters and Johnson. Of course, watching wasn't enough. This is science! So you also had sensors hooked to you and your partner that would measure sexual response, monitoring your mojo the same way a polygraph test detects when you're lying. Only instead of measuring your lies, it's measuring how bad of a job you're doing at arousing a total stranger.
Putting the "strange" in "sex with a total stranger," partners were matched randomly (if you still think that sounds awesome, the next time you're in line at Burger King, imagine getting randomly matched up for sex with any one of the people around you). Oh, by the way, the subjects ranged in age from 18 to 89.
We'll let that sink in for a moment.
We're not knocking the work Masters and Johnson did--it was absolutely revolutionary and totally changed the way the modern world thinks about sex. We're just saying it wasn't the erotic carnival of flesh the subjects probably had in mind upon entering a sex laboratory. And in case it's not obvious enough that this was a worse deal for the women involved, they had the added bonus of having their orgasms studied via a prosthetic penis with a video camera in it.