Dyadic interrelations in lifespan development and aging: how does 1 + 1 make a couple? - introduction

Lifespan development and aging do not take place in a vacuum. It is increasingly recognized that others, who may be very familiar such as marital partners, often play a key role in shaping the developmental trajectories of their spouses. Further, this shaping seems at least partially dependent on the prolonged interactions that result in a high level of familiarity that is conducive to affecting the feelings, actions and reactions of the other member of the dyad. The studies comprising this special series on dyadic relationships tackle a number of specific mechanisms by targeting 2 domains of functioning that are central to successful aging, namely aspects of cognitive functioning and subjective well-being. The 4 papers adopt a range of methodologies, from an experimental session to short- and longer-term longitudinal observational studies. The authors of these articles offer novel insights into the theoretical underpinnings of spousal interrelations as well as how to approach such issues analytically. The closing discussion article draws out some of the underlying themes and highlights the important promises, but also the distinct challenges, of research on couples and dyads. Key avenues for future research are outlined, especially adapting principles of an epidemiological approach to understanding cognitive aging, broadly defined. These promise to extend our understanding of dyadic interrelations in lifespan development and aging.