Habituation as a model of human aging

This article introduces a new partial model of human aging that centers around the process known as habituation. The essence of habituation is progressive response decrement to a stimulus as the organism's exposure to this stimulus increases. Basic concepts and studies of habituation in its traditional sphere--infancy and early childhood--are reviewed. It is pointed out that habituation is a process that has been identified very early in life and which is intimately related to major psychobiological variables, capable of generalization, and thought to have enduring characteristics. It is further suggested that there is a striking resemblance between habituation and core features of the "aged state." The amenability of habituation to clear-cut experimentation and precise quantification is also noted. The possibility is presented that aging might be regarded as a disorder of habituation. The phenomena of hyper- and hypo-habituation are briefly discussed, along with several problems and potentials in this new model of aging.