People with negative childhood experiences explore less and are underweight.


Adverse childhood experiences (ACE) are extreme stressors that have a profound impact on cognitive development. Using an exploration/exploitation paradigm of foraging, we demonstrate that ACEs are associated with reduced exploration, leading these individuals to accumulate fewer rewards from their environment. Using computational modeling, we identify that reduced exploration is associated with ACE-exposed individuals underweighting reward feedback, highlighting a cognitive mechanism that may link the trauma of the childhood to the onset and maintenance of psychopathology.


Negative childhood experiences (ACE) are extreme stressors that lead to negative psychosocial outcomes in adulthood. Non-human animals explore less after being exposed to early stress. Therefore, in this preregistered study, we hypothesized that reduced exploration after ACEs would also be evident in human adults. Moreover, we predicted that adults with ACEs, in a foraging task, would adopt a decision-making policy that relies on most recent reward feedback, a rational strategy for unstable environments. We analyzed data from 145 adult participants, 47 with four or more ACEs and 98 with fewer than four ACEs. In the foraging task, participants assessed the trade-off between mining a known patch with decreasing rewards and exploring a new patch with a new distribution of rewards. Using computer modeling, we quantified the degree to which participants’ decisions weighted recent comments. As expected, participants with ACEs explored less. However, contrary to our hypothesis, they underweight recent feedback. These unexpected results indicate that early adversity can dampen reward sensitivity. Our findings may help identify the cognitive mechanisms that link childhood trauma to the onset of psychopathology.


    • Accepted November 18, 2021.
  • Author contributions: research designed by AL, RTM and NF; AL did some research; AL analyzed the data; and AL, RTM and NF wrote the article.

  • The authors declare no competing interests.

  • This article is a direct PNAS submission. MB is a guest editor invited by the editorial board.

  • This article contains additional information online at

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