Motivation
Motivation is a multiplicative function of expectancy (i.e. a person's beliefs about the probability that their action will lead to the outcome) and value (i.e. the value of the outcome or satisfaction the person will receive if he/she achieves the outcome).
Kraut, R. E., Kiesler, S., & Resnick, P. (2016). 2. Encouraging Contribution to Online Communities . In Building successful online communities: Evidence-based Social Design. essay, MIT Press.