Expected sights speed reactions but blur memory, study suggests
University of Sydney researchers found predictable visual events prompted faster responses, while surprises were remembered with greater spatial precision.
By Tom Brennan · Health & Medicine Correspondent
2 min read
People responded faster to visual events they expected, but later remembered those events less precisely than surprises, according to research published in JNeurosci. The findings address a long-running debate over whether the brain saves effort by sharpening predictions or by giving priority to new information.
The Society for Neuroscience said Reuben Rideaux and colleagues at the University of Sydney studied how expectation and attention affect both action and memory. Their results suggest the brain can use both approaches, with prediction helping movement before an event and surprise improving sensory encoding after it occurs.
In the study, researchers altered what participants expected while they predicted where visual targets would move, according to the Society for Neuroscience. Participants reacted more quickly when events matched their expectations, but their memory for those expected events was less exact than their memory for unexpected events.
Attention changed one part of the pattern, the researchers reported. When volunteers were more motivated to track the position of the visual information, expected events produced even faster responses, but memory for those events still lacked the precision seen with unexpected ones.
The Society for Neuroscience said the work speaks to two views in neuroscience. One view holds that the brain operates efficiently by improving its internal models of events that are likely to happen. Another holds that the brain gives extra processing to events that violate expectations because they carry fresh information.
Rideaux said the study indicates both views capture part of the process. In his account, expected events appear to receive an early boost that prepares action, while unexpected events receive later sensory priority that supports more accurate memory.
The researchers also found that differences among participants in memory precision were associated with how sharply events were represented in the brain, according to the Society for Neuroscience. The report did not provide participant counts in the summary released with the study.
Rideaux used tennis as an example to explain the result. A player who anticipates a serve to one side can begin moving before the ball arrives, gaining time for the return; the same player may later recall the exact landing spot less clearly than she would for an unusual serve that broke the pattern.
That example reflects the study’s broader conclusion: prediction can help the body act quickly, while surprise can leave a stronger record of where something happened. The paper was published in the Journal of Neuroscience in 2026, according to the publication details listed by the Society for Neuroscience.
This story draws on original reporting from Medical Xpress.