Para is from Greek, and means "beside, closely related to, beyond..." The term parapsychology was coined in or around 1889 by philosopher Max Dessoir. It was adopted by J. B. Rhine in the 1930s as a replacement for the term psychical research in order to indicate a significant shift toward experimental methodology and academic discipline.[7] The term originates from the Greek: παρά para meaning "alongside", and psychology. In parapsychology, psi is the unknown factor in extrasensory perception and psychokinesis experiences that is not explained by known physical or biological mechanisms.[8][9] The term is derived from the Greek ψ psi, 23rd letter of the Greek alphabet and the initial letter of the Greek ψυχή psyche, "mind, soul".[10][11] The term was coined by biologist Berthold P. Wiesner, and first used by psychologist Robert Thouless in a 1942 article published in the British Journal of Psychology.[12] The Parapsychological Association divides psi into two main categories: psi-gamma for extrasensory perception and psi-kappa for psychokinesis.[11] In popular culture, "psi" has become more and more synonymous with special psychic, mental, and "psionic" abilities and powers.