15.08.2025 Eye movements are not for nothing: Marburg psychologists reveal hidden “gaze costs”

Even the smallest movements of the eyes require the brain to weigh up the benefits against the effort involved

Lightning-fast eye movements also cost energy. The brain optimizes the cost-benefit ratio here.

Even the smallest movements of the eyes require the brain to weigh up the benefits against the effort involvedWe move our eyes countless times a day - to read, take in our surroundings or recognize faces. These quick eye movements, known as saccades, are often considered “free” because they hardly consume any energy. However, psychologists Prof. Dr. Alexander Schütz (Philipps University Marburg) and Dr. Emma Stewart (Queen Mary University of London) have now shown in a recent review article: Even these tiny movements are associated with hidden “costs” - for example, delays or loss of visual information or cognitive planning effort.

Underestimated “gaze costs”

“With every eye movement, the brain unconsciously weighs up possible benefits and possible costs for us,” explains Alexander Schütz. “We wanted to show that these costs have so far been underestimated - and that they are just as important for controlling our gaze as the prospect of new information or reward.” The analysis summarizes current findings from numerous studies in which researchers have investigated when and where eye movements are made and how these movements take place.

Unlocking the costs

The research duo Alexander Schütz and Emma Stewart make it clear that many of these gaze costs cannot be measured directly, but can only be determined indirectly - for example through mathematical models or neurophysiological experiments. Future research must investigate more closely how the brain combines different types of benefits and costs in order to choose the “best possible” gaze. The results appear in the journal Nature Reviews Psychology (https://rdcu.be/eAm69) and could help to better understand how visual perception, eye movements and decision-making processes interact in the long term.

Original publication: Alexander Schütz, Emma Stewart, A review of the costs of eye movements, Nature Reviews Psychology (2025), https://doi.org/10.1038/s44159-025-00481-7