Complex sentence: James D. Hardy, Herbert G. Wolff, and Helen Goodell of Cornell University proposed the unit based on their studies of pain during the 1940s-1950s; they defined one dol to equal to "just noticeable differences" (jnd's) in pain.
Split into simpler sentences: James D. Hardy, Herbert G. Wolff, and Helen Goodell of Cornell University proposed the unit based on their studies of pain during the 1940s-1950s. They defined one dol to equal to "just noticeable differences" (jnd's) in pain.