The basic idea underlying efficiency wage theory is that there is a link between workers' productivity and the wages they receive. As seen in the previous chapter, the relationship mainly lies in a situation of asymmetric information. In adverse selection models, the firm cannot distinguish the most efficient workers from the less efficient and a worker's ability is assumed to be correlated with his reservation wage. Then in a situation of involuntary unemployment, the firm may choose not to decrease wages so that the most productive individuals do not give up applying for the jobs. In moral hazard models, individuals' performances depend on their behaviour which cannot be perfectly monitored by employers. Offering higher wages makes the cost of losing one's job higher and thus urges workers to make every effort required to keep their jobs. In other models, a wage policy is a means of stabilizing the labour force when turnover is costly. Finally, in analyses of sociological inspiration, the wage policy is the product of social conventions determining work rules and collective productivity standards.

All these models show that real wage rigidity within an involuntary unemployment context is perfectly compatible with a competitive labour market. However, if the efficiency wage theory explains the existence of involuntary unemployment, using it as an element of macroeconomic analysis aiming at explaining the fluctuations in output and employment is not self-evident.