New evidence is tilting the debate about when cognitive ability peaks.

What if fluid intelligence — the capacity to analyze new information and solve novel problems — were not the most critical cognitive ability for predicting important life outcomes? What if no single “peak” in life existed — just different strengths that emerge at different ages? 

Psychologists Gilles Gignac and Marcin Zajenkowski of the University of Western Australia and the University of Warsaw, respectively, took on these questions in a recent study in the journal Intelligence. The scholars analyzed success-related cognitive and personality traits such as emotional intelligence, financial literacy, moral reasoning, resistance to sunk-cost bias, cognitive flexibility and cognitive empathy. Then they extracted age-related findings from 10 published studies and standardized the scoring for comparability. 

Gignac and Zajenkowski weighted the traits according to their importance for real-world functioning and created what they called a Cognitive-Personality Functioning Index. They found that when valuing experience-based capacities — emotional intelligence, financial literacy, moral reasoning — alongside cognitive abilities, the “sweet spot” appears around age 55 to 60. This doesn’t mean that 60-year-olds are “better” than 30-year-olds; rather that late midlife might have the most balanced portfolio of capabilities.

However, human capability doesn’t rise to one summit and then decline. Instead, it’s more like a mountain range; there are different peaks at different ages, and each is valuable for different challenges. 

The finding builds on an idea first proposed by psychologist Raymond Cattell in 1943: the distinction between fluid and crystallized intelligence. Fluid intelligence, Cattell argued, is characterized by processing speed and abstract thinking, and it peaks as people enter their third decade. However, crystalized intelligence, which is characterized by accrued knowledge and vocabulary, continues to rise through the middle of one’s seventh decade. 

In Gignac and Zajenkowski’s analysis of 16 dimensions of psychological functioning, they found that some traits and capabilities have different peaks. For example, emotional intelligence climbs through early adulthood and peaks in the forties; conscientiousness and emotional stability both increase into the fifties and sixties; and moral reasoning improves throughout adulthood. 

This maps with 2016 research from Harvard, which concluded that cognitive tasks peak at different ages. For example, early adulthood is characterized by a peak in raw processing speed, and comprehension peaks in midlife. In addition, when combining these observations with molecular changes, recent studies from Stanford affirm the nonlinear nature of aging by studying inflection points and waves in biological data throughout lifespans.

As we live longer lives, understanding these shifting strengths is crucial. The 25-year-old may bring speed and fresh perspective. The 50-year-old may bring integration and judgment. The 75-year-old may bring wisdom and pattern recognition across decades. Lastly, peaks throughout life are dynamic and are not predetermined, as the amplitude and duration of each peak varies between people, revealing malleability through the intersection of biology, lifestyle and behavior. The question isn’t which age is “better.” It’s recognizing that each stage brings different advantages.

Katherine Healzer is a Stanford undergrad majoring in biology. She is a Barry Goldwater Scholar for excellence in research and is director of Harps for Hospice.