Studying how the “whole brain” resolves ambiguity—rather than just the amygdala—could unlock new ways to treat stress-related conditions. Credit: Neuroscience News

Brain’s Default Setting for Ambiguity Matters for Mental Health

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·April 6, 2026

Summary: When you see a facial expression that could be either surprised or shocked, does your brain instinctively label it as “good” or “bad”? This split-second reaction is known as valence bias.

A new review suggests that how we interpret ambiguity is a core part of our personality and a major “red flag” for future mental health. While children typically start with a negative bias and shift toward positivity around age 10, those who stay “stuck” in a negative loop face a significantly higher risk of depression, anxiety, and stress-related physical illnesses later in life.

Key Facts

• The Positivity Shift: Valence bias evolves over a lifespan. Humans generally move from a “negative-first” perspective in early childhood to a more positive outlook starting at age 10, a trend that continues into old age.
• Risk Marker: Adults who maintain a strong negative valence bias are statistically more likely to experience chronic stress, which can lead to a range of physical health problems beyond mental health.
• Brain Network Discovery: While emotion research usually focuses on the amygdala (the fear center), Neta discovered that resolving ambiguity actually activates the cingulo-opercular network, which is responsible for cognitive control.
• Early Intervention: Because this bias is a “reliable” trait shaped over time, psychologists believe simple tests of valence bias could be used as early screening tools to identify children at risk for depression before symptoms even appear.
• Holistic Brain Function: The research argues that “threat detection” (spiders/snakes) is a localized process, but “ambiguity resolution” requires the whole brain to work together to decide what a situation means.

Source: University of Nebraska–Lincoln

In a split second, the brain determines whether an ambiguous situation is good or bad — and those snap judgments can reveal important information about a person.

A new article by Husker psychologist Maital Neta suggests that these responses, known as valence bias, could help identify risk factors for depression, anxiety and other stress-related conditions, and unlock secrets about how the brain works.

Neta, Happold Professor of Psychology and resident faculty in the Center for Brain, Biology and Behavior at the University of Nebraska–Lincoln, published a review in Current Directions in Psychological Science.

The article explores the next phase of understanding valence bias across brain networks, and the mental and physical health implications for individuals based on their valence bias.

“There’s been a lot of attention paid in the literature to how people respond to threats, such as spiders or snakes or fearful faces, but much less attention has been paid to how people respond to ambiguity,” Neta said. “How people approach ambiguity says a lot about them. It’s a pretty reliable thing about you that’s shaped over the course of your life.”

Valence bias develops over the whole lifespan, Neta said. Children are more likely to have a negative valence bias, but around age 10, there is a shift in most children, and they begin to be able to see things more positively. And this shift toward positivity continues throughout aging — older adults typically have more of a positive bias than younger adults. 

“It has important implications,” she said. “It’s associated with things like depression symptoms, anxiety symptoms, if you are somebody that tends to always interpret these things as being more negative.”

Research shows that children who do not make the transition from predominantly negative to more positive valence bias are at higher risk for depression and anxiety later in life. Similarly, adults with a more negative valence bias are more likely to experience those conditions.

“And that negativity can be linked with greater stress, which can lead to a range of health problems,” Neta said.

Beyond mental health outcomes, studying responses to ambiguity may also offer insights into how brain networks interact. For decades, research focused primarily on specific brain regions, such as the amygdala, which plays a central role in processing emotion — particularly fear and anxiety. However, in earlier magnetic‑resonance imaging studies of valence bias, Neta made an unexpected discovery.

Instead of finding activation of the amygdala, she found activation of the cingulo-opercular network, which is thought to support cognitive control.

“There really needs to be a much greater appreciation of the entire brain, because your whole brain is kind of working through these situations,” Neta said. “There’s a whole network of regions that are really important and help resolve what’s happening in front of you. Considering the whole brain would really enrich the science moving forward.”

Looking ahead, Neta said she believes that simple assessments of valence bias could be used as early interventions, particularly for children. She is continuing to explore this possibility in forthcoming research.

“If we see that kids are not shifting away from the negativity, and we think they are more likely to develop something like depression or anxiety, can we get in there early and try to help them to shift the bias so that they’re put on a better path?” she said.

Key Questions Answered:

Q: If I’m a “glass half-empty” person, am I destined to be depressed?

A: Not necessarily, but a persistent negative valence bias is a known risk factor. The “glass half-empty” mindset means your brain is working harder to resolve ambiguity as a threat. The good news? Because this is linked to the cingulo-opercular network (the brain’s control center), it suggests these biases can be “re-trained” through cognitive interventions.

Q: Why do 10-year-olds suddenly become more positive?

A: This is a major developmental milestone. Around age 10, the brain’s executive control regions begin to mature. This allows kids to move past the “safety-first” negative survival instinct of early childhood and start using context to see the “bright side” of ambiguous social cues.

Q: How is “ambiguity” different from a “threat”?

A: A threat is a snake in the grass—your amygdala reacts instantly to keep you alive. Ambiguity is a friend’s “blank” text message. Your brain has to choose how to feel about it. How you make that choice tells scientists more about your long-term mental health than how you react to a snake.

Editorial Notes:

• This article was edited by a Neuroscience News editor.
• Journal paper reviewed in full.
• Additional context added by our staff.

About this mental health research news

Author: Sean Hagewood
Source: University of Nebraska–Lincoln
Contact: Sean Hagewood – University of Nebraska–Lincoln
Image: The image is credited to Neuroscience News