Would be nice to see. Doesn't look like a hard experiment. Even a 12-lead ECG is pretty easy to set up compared to an EEG, PET scanner, or something like that. There's a very direct line from the heart to the sympathetic and parasympathetic nervous systems so it's quite believable that at least some of the "Big 5" should manifest in HRV. The reliability of their test doesn't seem far off from conventional personality tests

https://www.psychologytoday.com/us/blog/people-unexplained/2...