The areas of the tongue sensitive to tastes. The classical theory about the physiology of taste recognizes the existence of four fundamental tastes - sweet, salty, sour and bitter - each being perceived by specific areas of the tongue by means of gustatory receptors, also known as taste buds.
Theories of Aging. Theories of Aging. Erik Erikson, who took a special interest in this final stage of life, concluded that the primary psychosocial task of late adulthood (65 and beyond) is to maintain ego integrity (holding on to one's sense of wholeness), while avoiding despair (fearing there is too little time to begin a new life course).
The activity theory, also known as the implicit theory of ageing, normal theory of ageing, and lay theory of ageing, proposes that successful aging occurs when older adults stay active and maintain social interactions.he activity theory rose in opposing response to the disengagement theory. The activity theory and the disengagement theory were the two major theories that outlined successful aging in the early 1960s. The theory was developed by Robert J. Havighurst in 1961.