Psychology (Humanities), 1948
Fashionable way to describe something which has variations similar to a colour chart despite there being no objective evidence it exists. Makes you sound “scientific” and intellectual™.
The electromagnetic spectrum quantitively measures the frequencies of light, radio/audio, and other phenomena. Kinsey’s research into sexual behaviour in 1948 led to sociologists misappropriating the nice colours of electromagnetic spectrographs to suggest a “spectrum” of human sexuality (1980, Michael Storm EROS scale) and “gender identity” (no legitimate sources, but widely discussed).