Edited by Susan T. Fiske, Princeton University, Princeton, NJ, and approved October 16, 2014 (received for review August 6, 2014)
This paper is the first to demonstrate, to our knowledge, that people audit the meaningfulness of their lives as they approach a new decade in chronological age, further suggesting that people across dozens of countries and cultures are prone to making significant decisions as they approach each new decade. The paper has broad implications for interdisciplinary science, because it demonstrates a striking pattern in human behavior that bears on, among others, the disciplines of psychology, medicine, sociology, economics, and anthropology.
Although humans measure time using a continuous scale, certain numerical ages inspire greater self-reflection than others. Six studies show that adults undertake a search for existential meaning when they approach a new decade in age (e.g., at ages 29, 39, 49, etc.) or imagine entering a new epoch, which leads them to behave in ways that suggest an ongoing or failed search for meaning (e.g., by exercising more vigorously, seeking extramarital affairs, or choosing to end their lives).
↵1A.L.A. and H.E.H. contributed equally to this work; author order was determined alphabetically.
Author contributions: A.L.A. and H.E.H. designed research, performed research, analyzed data, and wrote the paper.
The authors declare no conflict of interest.
Data deposition: The data reported in this paper have been deposited in the Inter-University Consortium for Political and Social Research database, doi.org/10.3886/E18882V2.
*We also ran a supplemental analysis to address the possibility that experimental participants sought meaning more intently merely because they were focusing on the more distant future. Specifically, whereas the baseline condition asked participants to think about “tomorrow” and the birthday control condition asked them to think about their upcoming birthday (no more than 12 months away), experimental participants imagined the night before they reached a new decade in age (up to 10 years away). We found that, among participants in the experimental condition, there was no significant relationship between how many years until participants reached the next decade in age and the tendency to seek meaning, r (105) = 0.02, P = 0.87. This result suggests that the results in study 2 were not driven by differences in how far into the future participants focused across the three conditions.
†We decided to focus on male users of the dating website because biological and evolutionary research suggests that males are more likely than females to assert their sexual prowess by seeking out multiple partners (14). Leading to the same conclusion through a different route, the biopsychosocial construction of sex differences (15) suggests that men and women conform to the gendered roles prescribed by the societies in which they live. Consequently, the act of seeking out an extramarital affair, like purchasing a red sports car, is one of the canonical indicators that a man (but not a woman) has experienced a so-called midlife crisis. In this respect, 9-ending ages prompt end-of-decade crises that resemble midlife crises. Despite focusing on men, we ultimately obtained data on female users and found a similar though less-pronounced pattern of results.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1415086111/-/DCSupplemental.
