We were interested in the possibility of there being different age trends during different developmental periods. To examine the functional form of the developmental trends in greater detail, we fit a series of connected-linear spline models for each outcome. We selected the ages of 3, 15, 30, and 60 years as turning points. As discussed earlier, these ages have been highlighted in previous research and represent the transition from temperament into childhood, the transition from childhood into emerging adulthood, the transition into fully mature roles such as work and marriage, and the transition out of work. In total, we fit 17 linear models for each outcome: the mean effect size, a linear model with a single slope, and every logical combination of the break points from a model containing two slopes to a model containing five slopes. These variations allow for a full examination of whether the age-trends in the outcomes differ depending on developmental period in a manner that our continuous exponential model would not be able to detect. To compare the results of the linear-spline models with a continuous function, we fit an exponential model to the aggregated data for each outcome. This model had the form of
