The term is most often found in specialised works on psychology, neurobiology, and memory, though it was used in the same general way at least as early as the first half of the nineteenth century in works on rhetoric, logic, and philosophy.
Istilah tersebut paling sering ditemukan dalam karya-karya spesialisasi pada psikologi, neurobiologi dan memori, meskipun telah digunakan secara umum, setidaknya sejak paruh pertama abad kesembilan belas dalam karya-karya retorika, logika dan filsafat.