Clayton Paul Alderfer (born September 1, 1940, in Sellersville, Pennsylvania) is an American psychologist who further developed Maslow’s hierarchy of needs by categorising the hierarchy in his ERG theory (Existence, Relatedness and Growth).
Alderfer argued that once an individual’s basic needs for food and shelter have been met, their next concern becomes relatedness or the need for social interaction and a sense of belonging. Once these needs have been satisfied, individuals are motivated by the need for personal growth and development.
Alderfer’s ERG theory is a more flexible version of Maslow’s hierarchy of needs. It recognises that individuals may move backwards and forwards between the different levels of need depending on their circumstances.