Why do we remember some things more easily than others—and why do we often favor information that aligns with what we already believe? These two common tendencies, long studied in psychology and neuroscience, may have more in common than previously thought.
New research suggests that the same brain region might underlie both, helping explain how our prior experiences shape how we learn, remember, and make decisions.
A new study by Dingrong Guo and Yee Lee Shing, published in European Psychologist (2024), explores how two well-known cognitive phenomena—the memory congruency effect and confirmation bias—may be linked through shared neural processes.
Their review highlights the role of the medial prefrontal cortex (mPFC), a brain area known for its involvement in memory and decision-making, in both effects.
At the heart of the paper is the finding that both the tendency to remember information that fits with prior knowledge (the memory congruency effect) and the tendency to favor information that confirms preexisting beliefs (confirmation bias) involve the mPFC.
More specifically, the study suggests that two subregions of the mPFC—the ventromedial (vmPFC) and dorsomedial (dmPFC)—may have distinct but complementary roles in processing congruent information and guiding belief-consistent decision-making.
The memory congruency effect refers to our enhanced ability to remember new information that aligns with what we already know. For example, people are more likely to recall a word that fits naturally into a familiar sentence than one that does not.
This is thought to occur because congruent information is more easily integrated into existing mental frameworks, or schemas.
Neuroimaging studies have shown that when people successfully encode congruent information, the vmPFC is more active—a sign that it helps evaluate and consolidate new material that fits prior knowledge.
Confirmation bias, by contrast, emerges during decision-making.
It involves favoring, remembering, or interpreting information in a way that supports existing beliefs. This bias is common in many domains, from politics to health decisions.
For instance, someone might readily accept a news article that aligns with their views but dismiss contradictory evidence.
Studies have shown that when people encounter belief-consistent information, their brain’s reward circuitry is more active, and areas like the dmPFC become more engaged, especially when assessing and endorsing confirming evidence.
Guo and Shing argue that both effects stem from how the brain handles congruent information—whether in memory or judgment—and that the mPFC plays a central role in detecting and reinforcing these consistencies.
The vmPFC appears to serve as a kind of “congruency detector,” evaluating whether new inputs align with existing knowledge or beliefs. If they do, this area helps integrate them into memory or decision frameworks.
The dmPFC, on the other hand, is more involved in applying cognitive control, such as adjusting decisions or evaluating evidence strength.
Why does this matter?
Understanding how prior knowledge shapes both memory and belief can help explain why people often remember things selectively or stick to their existing views despite contrary evidence.
This has implications for education, public communication, and mental health. For example, interventions designed to promote critical thinking or reduce cognitive bias could benefit from targeting the processes identified in the mPFC.
It also helps explain why learning new information or changing one’s mind can be so challenging—it requires overcoming a brain system optimized to favor what is already known or believed.
The study also draws on evidence from developmental neuroscience to examine how these processes change with age.
Interestingly, the vmPFC, associated with detecting congruent information, tends to develop earlier and remain stable across the lifespan, while the dmPFC, linked to belief updating and decision-making, shows more variability.
This could explain why older adults may rely more on prior knowledge in memory tasks, and why adolescents may show distinct patterns of belief formation or bias, influenced by the later development of the dmPFC.
While the review draws on a broad set of existing studies, the authors note that more work is needed to fully understand how these mechanisms interact.
In particular, experimental research linking memory encoding and decision-making within the same individuals across time would help clarify whether the same neural pathways are consistently involved.
Future studies may also benefit from using lifespan samples to explore how these effects evolve from childhood to old age.
Overall, this research offers a compelling framework for thinking about how our memories and decisions are shaped by what we already know and believe.
It suggests that instead of operating in isolation, memory and belief biases may arise from shared brain systems that prioritize coherence and efficiency over objectivity. This may be adaptive in some situations, but also highlights the cognitive cost of deeply rooted mental shortcuts.
Citation
Guo, D., & Shing, Y. L. (2024). Linking the congruency effect in memory to confirmation bias in decision-making across the lifespan—Common roles of the medial prefrontal cortex: A selective review.European Psychologist, 29(4), 245–256. https://doi.org/10.1027/1016-9040/a000536
