Depression is linked to a genuine pessimistic bias rather than a realistic view of the world

A recent study published in the journal Behaviour Research and Therapy provides evidence that people experiencing symptoms of depression hold genuinely pessimistic biases about future positive events, rather than simply viewing the world more realistically. The research suggests that while individuals with depression can update their beliefs when desirable things happen, these hopeful shifts tend to be fragile and easily reversed.

The study was designed to test whether the negative thinking patterns seen in depression reflect a genuine bias or just an absence of normal optimism. For decades, experts have debated the idea of depressive realism, a concept suggesting that depressed individuals actually see the world more accurately than healthy individuals, who tend to be overly optimistic. To test this, the researchers wanted to see how people predict everyday life events and how they adjust those expectations when real life proves them wrong.

“We know that depression involves a generally pessimistic outlook on life. Previous research has shown that people with high depressive symptoms tend to underestimate the likelihood of positive outcomes in their lives,” said study author Joe Maffly-Kipp, a postdoctoral fellow in the Mood & Individual Differences Lab (MIND Lab) at The Ohio State University Wexner Medical Center.

“However, less is known about how symptoms of depression are related to ‘learning from experience.’ For example, if someone thinks that a positive outcome is unlikely, but then it keeps happening, do they then predict that it is more likely to happen again in the future? Uncovering how learning works in depression is important for understanding how/why people develop depression and stay depressed, and may help to inform future treatments.”

The scientists focused on commonplace occurrences, like having a conflict with a partner or receiving a gift, because these routine experiences are highly relevant to daily moods. By tracking how people update their beliefs over time based on actual experiences, the scientists hoped to uncover the mechanisms that keep people stuck in a depressed state.

The scientists recruited 372 adult participants through an online platform. The sample was specifically chosen to include people with either highly elevated depressive symptoms or very low depressive symptoms. Participants completed a survey where they evaluated a list of 40 common life events.

Half of these events were positive, like taking a leisure trip, and half were negative, like getting a headache. For each event, participants estimated the percentage chance that it would happen to them in the upcoming month. At the same time, the participants reported whether each of those exact events had happened to them over the previous month.

The researchers contacted the participants again one month and two months later to repeat the exact same survey. This setup gave the scientists three separate time points to observe how initial predictions matched reality. It allowed them to measure how expectations shifted after participants saw what actually happened in their lives.

The findings indicate that depression is strongly linked to expecting and experiencing fewer desirable outcomes. People with high levels of depression displayed a clear pessimistic bias, specifically regarding positive events. They consistently predicted that positive events were less likely to happen than they actually were.

People with low depression levels showed an optimistic bias by overestimating how often good things would happen. This pattern supports the idea that depression involves an active distortion of reality toward the negative, rather than a purely realistic outlook. The scientists also found that higher depression levels were associated with less accurate predictions about negative events, regardless of whether the specific guess leaned positive or negative.

When looking at how people changed their minds over time, the researchers noticed an unexpected pattern. Participants with elevated depression were actually more likely to adjust their predictions about positive events based on real-world feedback. If a positive event occurred, they readily updated their expectations for the following month to be more optimistic.

However, this newfound optimism tended to be incredibly fragile. By the third month of the study, people with high depression were highly likely to reverse their optimistic updates, dropping their expectations back down. Their beliefs about positive events essentially bounced back and forth in a pattern of oscillation.

In contrast, when these individuals updated their beliefs about negative events, those updated expectations became deeply entrenched. They were much less likely to reverse their predictions about negative events later on. This suggests that people with depression might overvalue internal negative thoughts and too quickly discard external positive evidence.

“Overall, our findings support the idea that people with depression are more pessimistic, and their beliefs about negative events may be harder to shift,” Maffly-Kipp told PsyPost. “Beliefs about positive events might be more volatile, which could contribute to cycles of hope and disappointment in depression.”

The findings cast doubt on the theory that depressed individuals tend to have more realistic expectations. “While our work did show that the least depressed people were overly-optimistic, we also showed that people high in depression were pessimistic ‘by definition,’” Maffly-Kipp explained. “In other words, they predicted positive outcomes as being less likely than how often those events actually occurred in the next month, on average. This suggests that depression is associated with unrealistically negative expectations about one’s life.”

The study does have some limitations, such as relying entirely on self-reported surveys and using artificial numerical percentages to measure complex human expectations. Asking people to assign a specific probability to a life event is not perfectly natural and might change how they normally process their daily outlook.

Looking ahead, the scientists hope to examine how to help individuals hold onto positive expectation changes.

“We hope to better understand what allows for true, stable learning in depressed populations,” Maffly-Kipp said. “Many therapies for depression depend on the idea that we can help people to build more optimistic ways of thinking about themselves and the world. Our work suggests that this learning process may be more complex than it seems, and these updated ways of thinking may not last over time. By understanding what helps positive changes last, and who is most likely to maintain them, we may be able to improve therapy and help people recover more effectively.

The study, “Learning from experience: Depressive bias and updating beliefs about common life events,” was authored by Joseph Maffly-Kipp, Daniel R. Strunk, Robert J. Zhou, and Jay C. Fournier.