For example, many years ago Parsons (1968) defined
effort as the means by which motivation is translated
into accomplished work, implying that it can be seen as a
mediator between the unobservable psychological state of
motivation and work outcomes. More recently, Naylor,
Pritchard, and Ilgen (1980) as well as Ilgen and Klein
(1989) stated that motivation is the psychological state or
predisposition of the individual with respect to choices of
behavior, whereas effort is defined as the amount of energy
spent on an act per unit of time. In line with this literature,
motivation and effort are considered as conceptually distinct
here. Effort is a measurable behavior that is impacted
by motivation (Bandura & Cervone, 1986; Deci & Ryan,
1985; Locke, Shaw, Saari, & Latham, 1981).