Part CONCEPTS, THEORY, AND METHODS IN THE PSYCHOLOGY OF AGING 1 | 50 the Head Start program (Vinovkis, a, and the changes in welfare and employment policies enacted under the Clinton administration (cf. also Duncan, 2005; Hayward, 2008; Huston et alb SUMMARY AND FUTURE DIRECTIONS In this chapter I have tried to identify and discuss some of the major historical influences that might provide explanatory mechanisms fora better understanding of cohort and period differences in psychological aging processes. To do so within the confines of a single chapter I had to be selective rather than exhaustive in my inclusion of possible influences. Hence, I first proposed some theoretical arguments for why one should pay attention to historical influences in studying the aging process of various psychological constructs as individuals develop from young adulthood to old age and the end of their lives, and I then laid out some of the principal concepts that require attention when studying such historical influences. I next focused on historical changes in educational attainment, occupational structures, healthcare and lifestyles, the role of immigration, and the impact of social interventions to reduce poverty.
Out of necessity, I primarily covered historical influences that occurred in the United States. This, of course, led to a major omission by not attending to some of the major political changes that have transformed life and made a major impact upon psychological aging in other countries. Here I refer the reader to other more recent contributions that have discussed the impact on individual development by political events such as the German reunification
( Silbereisen et al., 2005 ) or the collapse of the Soviet Union ( Smyth, 2005; Titma & Tuma, 2005 ). Other historical influences that I slighted in this chapter and that deserve future exploration in relation to their influence on aging processes include changes in family structure ( Hagestad & Uhlenberg, 2007; Hughes & Waite, 2007 ), and the cultural transformation of the meaning of the aging experience (cf. Fry, 2008 ), as well as the dramatic changes in retirement expectations and practices (cf. Eckerdt, 1998, 2008 ). I have also not attended to historical transformations of the meaning of adult development in non-Western cultures (e.g., Ikels, 1989; Sangree, 1989; Usui, 1989 ).