Chapter 16 middle adulthood: social and emotional development. L01 theories of development in middle adulthood. Theories of development in middle adulthood largely deal with the issue of whether we can consider middle adulthood to be a distinct age or phase of life. Erikson"s theory of psychosocial development, middle adulthood is characterized by a particular life crisis. We shall describe that crisis and consider the evidence, pro and con. Daniel levinson spoke of a specific midlife transition and a midlife crisis (not to be confused with erikson"s life crises). Then we will take a broader look at the ways in which personality appears to change or not change during middle adulthood. Entering midlife: crisis, turning point, or prime of life: theorists mention 35 or 40 as entering midlife; 35 crucial to journalist gail. Five basic factors of personality (mccrae and costa) to study stability and change in personality development of adults over several decades.