Charting the Evolutionary Roots of Cognitive Biases

Why do people often overvalue what they already own, even when logic suggests they should not? A new article published in the Journal of Risk and Uncertainty explains why this “endowment effect”—a widely observed cognitive bias—may be best explained through the lens of evolutionary biology.

Linking Cognitive Biases: The successes of a test case that predicted variations in endowment effect magnitudes, authored by Vanderbilt Law Professor Owen Jones, appears in the August edition of the Journal of Risk and Uncertainty. Jones reviews a 20-year arc of research, by himself, primatologist Sarah Brosnan, and other colleagues, that connects cognitive biases to deep evolutionary roots.  The article was solicited for a tribute journal issue to Nobel Prize winner Daniel Kahneman, who co-pioneered bringing the study of cognitive biases into what is now known as the field of behavioral economics.

By testing predictions grounded in biology, the research arc by Jones and colleagues not only illuminates why the endowment effect exists but also demonstrates a method for predicting its variations across different contexts.

“Natural selection can bias decision-making toward choices that were rational in ancestral conditions but are mismatched to modern environments, yielding outcomes that are irrational yet predictably patterned,” the author writes.

The research team conducted a series of experiments, beginning with chimpanzees, to determine whether the endowment effect was unique to humans or shared across species. Four major discoveries, consistent with the new predictions of this approach, followed:

1. Endowment effect in primates: The endowment effect was found not only in humans but also in chimpanzees, orangutans, and gorillas.
2. Greater effect for foods: In primates, the effect was 14 times more likely when trading foods than when trading toys.
3. Context matters: The effect could be turned “on” or “off” depending on whether an item was useful in its immediate context.
4. Predictability in humans: In people, an item’s “evolutionary salience score”—a measure of its relevance to survival and reproduction—predicted more than half of the variance in endowment effect magnitudes across novel items.

“No other extant theory of the endowment effect predicted any of these results, either individually or as a connected set,” the author explains.

The paper traces many cognitive biases to evolved predispositions that were once adaptive but may now be mismatched to modern conditions. By grounding the study of decision-making in biology, researchers can better explain not just isolated biases, but also the broader patterns linking them.

As the author notes, “Cognitive biases provide a window into behavioral predispositions. And widespread patterns in behavioral predispositions often (though importantly not always) reflect psychological adaptations that are typical of a given species and honed by the ubiquitous evolutionary force of natural selection.”

The findings offer new tools for behavioral economists, psychologists, and policymakers seeking to anticipate when biases like the endowment effect will arise and how strongly they will affect decisions. More broadly, the approach suggests that other biases might also be systematically explained and predicted through evolutionary theory.

“The success of the approach summarized here not only deepens our understanding of the endowment effect. It also suggests more broadly that many other cognitive biases may be studied in similar fashion and potentially linked by a common conceptual understructure and deep theoretical framework,” the author concludes.

“Linking Cognitive Biases: The successes of a test case that predicted variations in endowment effect magnitudes” appears in Volume 71, Issue 1 of the Journal on Risk and Uncertainty. Owen Jones is the Glenn M. Weaver, M.D. and Mary Ellen Weaver Chair in Law, Brain, and Behavior and a Professor of Biological Sciences. He serves as Director of the MacArthur Foundation Research Network on Law and Neuroscience and Director of Weaver Family Program in Law, Brain Sciences, and Behavior at Vanderbilt Law School.