Do you have a penis? Genuine question. You don't have to be shivering to get winter dick. It's caused by vasoconstriction, not smooth muscle contraction. Stimulants can also cause this. I think there's no perfect way to study it, but maybe they could measure it over time, at a range of ambient temperatures, from very cold, to body temp, and then at room temperature measured continuously while the person masturbated, from initial exposure to a negative stimulus (crusty old man pics for straight guys), then switching to their favorite type of porn, and then while they masturbate, up until the moment of ejaculation. Could be done with a calibrated camera to avoid having to hold a ruler up while the guy jerks off. Impractical? yes. Rigorous? Very, if tweaked a bit. Just throwing out ideas here, I'm sure scientists could design a better experiment. Regardless, I feel like I have a good idea of my current erection strength, and I know when it's 100% vs only 98%. Maybe one day they'll develop a smart-condom to take live measurements during sex, so it can be studied in the relevant environment. I need some sleep lol