Maslow’s theory was one of the early theories of motivation, and unfortunately research never validated it, and Maslow did not provide any empirical substantiation. Later on Alderfer introduced a revised form, the “ERG Theory” Existence, Relatedness and Growth, his theory proposed that more than one need can be operative at the same time and it also had a regression-frustration dimension.This theory proved to be more in tune with our knowledge of individual differences.
McClelland had another Theory of needs where he focused on three needs: Achievement, Power, and affiliation. But that’s a whole different discussion.
