Surprise and brain function. Scientists explained why people's pupils dilate
A new study published on August 24 at 8:58 PM in Science Alert revealed the mechanism explaining the dilation of pupils during unexpected events. The study involving 63 healthy adults showed that their pupils dilated when participants observed colored images and tried to predict the next color if it did not match their expectations.
During the experiment, participants first memorized the colors they saw and then attempted to predict the next one. When a color appeared that did not meet their expectations, it triggered pupil dilation. Researchers recorded changes in brain wave activity and the system associated with norepinephrine. The norepinephrine system includes the locus coeruleus—a small group of neurons in the brainstem that plays a crucial role in responses to unexpected stimuli.
The brain can retain prior context, but after a situation changes, it needs to update it.
Matt Nassar, co-author of the study from Brown University
This indicates that after unexpected stimuli, participants updated their assumptions according to the new information. It turned out that the reaction to unexpected changes not only activates physiological changes but also facilitates the updating of information in the brain.
Pupils typically dilate in the dark to let in more light; however, this response is not limited to just lighting. Changes in pupil size and signals on the electroencephalogram may be external indicators of the process of updating information in the brain. Thus, the study underscores the importance of the role of unexpected events in learning and adapting our brain.
These results may have broad applications in understanding cognitive processes such as learning and adapting to new situations. As the brain's ability to respond quickly to unexpected changes is vital for decision-making, this research opens new avenues for further studies in neurobiology and psychology. Understanding the mechanisms behind these reactions may also aid in the treatment of disorders related to perception and information processing.
Understanding the mechanisms behind pupil dilation can provide deeper insights into cognitive responses. For a more detailed exploration of the brain signals involved in this fascinating phenomenon, check out how scientists have pinpointed the specific neural activity associated with widened eyes during moments of surprise in this related study.