People with adverse childhood experiences explore less as adults and may be less sensitive to positive rewards, according to a study published in the Proceedings of the National Academy of Sciences. Using a foraging paradigm, the researchers found evidence that reward-based decision-making may contribute to the psychopathology observed in people with childhood trauma.
An adverse childhood experience (ACE) is an extreme stressor that occurs during childhood that can lead to negative psychosocial outcomes later in life. Examples of ACEs include physical or emotional abuse, neglect, parental divorce, and parental imprisonment.
Psychology studies have found evidence that such negative childhood experiences affect the way people make decisions in the future, pulling them toward choices that maximize short-term benefits and limit exploration. For example, adolescents with early life stress prefer immediate rewards over delayed ones and explore less on a risk-taking task. While this strategy toward short-term rewards may be adaptive in volatile environments, findings suggest that it can lead to poorer outcomes in later life, like substance misuse.
“My interest in this topic stemmed from my time working in the youth justice system with young people who had experienced early adversity,” said study author Alex Lloyd, a research fellow at University College London. “Adverse childhood experiences were quite common in the young people who were in the criminal justice system and so I became interested in how experiences of early adversity might impact behavior later in life. My hope is that the more we can understand about the impacts of early adversity, the better we can support individuals who have experienced these events and prevent negative outcomes for them later in life.”
While previous research was conducted among adolescents, study author Lloyd and his colleagues wanted to explore how childhood stress might impact reward processing into adulthood. To do this, the researchers had a sample of adults complete a computerized task that used a patch foraging paradigm.
The patch foraging task was completed by 145 adults — 47 of whom reported a high number of ACEs and 98 of whom reported a low number of ACEs. The task had participants forage apples from a tree presented on screen. At each round, the participant had to choose whether to stay with the same tree, which gradually yielded fewer apples, or to explore a new tree with fresh rewards. There were also two different foraging environments. One was a poor quality environment, where it was most beneficial to explore less and exploit the same tree for longer. The other was a rich quality environment, where it paid off to explore more and spend less time with each tree.
The results revealed that participants with a higher number of ACEs explored less, meaning they stayed with the same tree for longer than participants with a low number of ACEs. Interestingly, compared to the low ACE group, the high ACE group placed less weight on recent reward feedback when making their decisions across the poor quality and rich quality environments. This ran contrary to the researchers’ hypothesis, which expected participants with a history of stress to place more emphasis on recent feedback, given that feedback from recent events is more useful in predicting the future within volatile, uncertain environments.
The authors said that their findings might be attributed to the fact that their paradigm tested decision-making to obtain rewards rather than to avoid punishment. Exposure to ACEs has previously been tied to an elevated response to punishment, and it could be that people with a history of stress are “overweighting feedback to avoid punishment and underweighting feedback to accumulate rewards.” The researchers noted that it may be interesting for future studies to investigate how adults with a history of trauma incorporate feedback from both punishments and rewards.
Participants with high exposure to ACEs collected fewer apples overall, suggesting their foraging strategies were less optimal compared to participants with low exposure to stress. Thus, although some findings were unexpected, the overall results were consistent with the notion that childhood trauma can influence decision-making and lead to negative consequences in adulthood.
“For participants who explored less, they collected fewer rewards from their surroundings relative to individuals without experiences of early adversity. We think a bias to explore less following early adversity may prevent people from taking advantage of opportunities in their environment (for example, exploring new career options) and so may help us to understand some of the outcomes in adulthood that are associated with childhood trauma,” Lloyd told PsyPost.”
“In addition, we found that people who experienced early adversity underweighted reward feedback, which was linked to their bias to explore less. Being able to use rewarding feedback (e.g., incentives such as praise or money) helps us to learn about our surroundings and underweighting reward feedback has been linked to mental health conditions such as depression, so we also think that these findings might help us to understand the links between childhood trauma and poor mental health later in life.”
But the study, like all research, includes some caveats.
“It’s really important to note that we didn’t study people over longer periods of time (which is known as a longitudinal design), so we cannot say that early adversity causes individuals to explore less or underweight reward feedback, as there may be other factors that contribute to these behavioral developments following adverse childhood experiences,” Lloyd explained.
“Future research needs to study people over repeated timepoints to study how individuals’ biases to explore and learn from reward feedback develop after experiencing early adversity. Once this evidence is established, we could begin to think about whether we can develop interventions that target exploration and reward learning to improve outcomes for individuals who experience early adversity.”
“I would just like to thank to the charity partners we collaborated with who made this research possible,” Lloyd added. “These charities were: National Association for People Abused in Childhood (NAPAC), Survivors South West Yorkshire, The Survivor’s Trust, and one anonymous support group. I would also like to thank the individuals who took part in the study for giving their time and sharing their experiences.”
The study, “Individuals with Adverse Childhood Experiences Explore Less and Underweight Reward Feedback”, was authored by Alex Lloyd, Ryan McKay, and Nicholas Furl.