Imagine walking through a park, hearing the crunch of leaves with each step. Now picture taking another step—but there’s no sound.
Your brain immediately notices something is off. This moment of surprise is called a “prediction error,” and it’s how your brain responds when what you expect doesn’t match what you experience.
Scientists at the Friedrich Miescher Institute (FMI) have been studying how our brains detect these surprises, and their findings could have big implications for mental health.
Our brains are like prediction machines. They constantly guess what we should see or hear based on our movements and past experiences.
When those guesses are wrong—like when you step and don’t hear a sound—certain neurons fire off strong signals. This is the brain’s way of saying, “Wait, something’s not right.”
Until recently, it was mostly known that this happens with sight. For example, when mice run through a virtual environment and the scenery suddenly freezes, their brains send out strong error signals. But what about sound?
To find out, Magdalena Solyga, a neuroscientist at FMI, designed an experiment with mice running through a dark hallway.
As they ran, the sound grew louder. Sometimes, the sound was cut off without warning. Just like with visual surprises, the mice’s brains responded strongly to the unexpected silence. This showed that prediction errors aren’t just limited to sight—they happen with sound too.
Solyga took things further by testing both sight and sound mismatches at the same time. Mice ran through the virtual space with both visuals and sounds tied to their movement. Occasionally, both would stop suddenly.
The mice’s brains reacted even more strongly than with just one sense, suggesting the brain is especially sensitive when multiple senses don’t match up.
The researchers then adapted this experiment for humans, using virtual reality and EEG recordings.
When the virtual world froze unexpectedly as participants walked, their brains also showed a strong reaction. This is just the beginning—next, the team plans to test combined mismatches in people to see how the brain handles multiple surprises.
Understanding how the brain detects these sensory mismatches could one day help diagnose psychiatric conditions.
If people with conditions like psychosis have unusual brain responses to these surprises, it could serve as a reliable marker for diagnosis or to measure treatment progress.
Though it may take time to bring this research to clinics, the findings offer a glimpse into how our brains process the unexpected—and why it matters for mental health.
Source: KSR.
