The standard theory of production treats human and non-human inputs in the same way. Inert Areas Theory drops this assumption. One distinction is obvious. Human capital, the source of human inputs, can not be purchased outright by firms. Usually what is purchased are units of labor time. What is critical is directed effort, at or beyond some level of skill. Direct effort, however, involves choice and motivation, and these are the critical variables left out of the standard theory. Leibenstein introduces the concept of "inert areas" by which he means "a set of effort positions whose associated levels of utility are not equal but in which the action required to go from a lower to a higher utility level involves a utility cost that is not compensated for by the gain in utility." This idea is used when discussing the behavior of firm's management.f firm's management