Building on this work, Cacioppo therefore moved away from drive-reduction toward measuring individual differences in the self-reward potential of cognitive activity, stressing (p. 118) that they were using the word need in the statistical sense of a "likelihood or tendency", rather than in the rudimentary biological sense of "tissue deprivation", they defined the need for cognition as an individual's tendency to "engage in and enjoy thinking" (p. 116) and the tendency to "organize, abstract, and evaluate information" (p. 124)—or, variously, as a stable, but individually different "tendency to engage in and enjoy effortful cognitive endeavors", or an "intrinsic motivation to engage in effortful cognitive endeavors... and exercise their mental faculties", or an "intrinsic motivation for effortful thought".