[2] Carstensen is best known in academia for socioemotional selectivity theory, which has illuminated developmental changes in social preferences, emotional experience and cognitive processing from early adulthood to advanced old age.
[3] By examining postulates of socioemotional selectivity theory, Carstensen and her colleagues (most notably Mara Mather) identified and developed the conceptual basis of the positivity effect.
[8] In 2011 she published A Long Bright Future: Happiness, Health and Financial Security in an Era of Increased Longevity.
[10] SST is a life-span theory of motivation which posits that people prioritize emotionally meaningful goals when time horizons are constrained.
[3][11] Consequently, people with limited time horizons tend to have smaller, more carefully selected social networks and experience better emotional well-being.