To describe how different variables contribute to psychological aging throughout human life, we trained DNNs on MIDUS 1 age group subsamples (25-39, 40-64, 65-75 years). These models contained the same 50 features as PsychoAge and Subjage, but their relative importance was not constant. In other words, a variable’s contribution to psychological aging was not static and its influence may vary with time.
First, we explored important variables (top-25 mean normalized PFI and DFS scores) shared by all age-group specific clocks to define the psychological aging core – features that significantly shift throughout one’s lifespan ( Table 2 ). Core features that determined the chronological aspect of psychological aging in MIDUS 1 contained neuroticism, seeing the community as a source of comfort and defining the lower boundary of male middle age. These features are expected to have life-long trends that let DNNs tell an old and a young person apart. Personality traits that were rendered important for human perception of age included aspirations scale, extraversion, openness, being career-oriented, and the prevalence of the positive reappraisal coping mechanism. Changes in these traits are expected to drive the internal psychological clock in humans of all ages.
Table 2
Effort put in life overall; Lower aspirations; Forcefulness; Current opinion about contributing to the well-being of others. Live for today; Persists in goal striving; Positive re-appraisal; Highest level of education; Current opinion about health. Now taking prescription medications for blood pressure; Marital status; Headaches frequency (30 days); Body mass index; Define age when men enter middle age; Community is a source of comfort; Neuroticism; Conscientiousness; Opinion about control of life in general; Define age women enter middle age; Mental health (self-evaluated); Sex life expectations in 10 years; Health locus of control others; Highest level of education; Contributing to the well-being of others in 10 years; Chronic conditions (12 months).