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).
Two major theories explain the psychosocial aspects of aging in older adults. Disengagement theory views aging as a process of mutual withdrawal in which older adults voluntarily slow down by retiring, as expected by society. Proponents of disengagement theory hold that mutual social withdrawal benefits both individuals and society. Activity theory, on the other hand, sees a positive correlation between keeping active and aging well. Proponents of activity theory hold that mutual social withdrawal runs counter to traditional American ideals of activity, energy, and industry.