ERG theory does not postulate a rigid hierarchy of needs where a higher-order need only become operative once a lower-order need has been satisfied substantially; therefor, in terms of ERG theory, two or even all three needs categories can influence behaviour simultaneously; and
ERG theory also suggest that, should one level of needs remains unsatisfied for a period, the person may regress to a lower-order needs category. Whereas Maslow held that a person will remain fixed on a particular need level until that need has been satisfied. ERG theory postulate that continued frustration of a need may cause an exaggerated desire to have a lower-order need satisfied. For example, a person who does not experience personal growth in his or her job (Frustration of the growth needs) may develop an inordinate need to earn a lot of money (An existence needs)