Millions of drivers on UK roads could be at heightened risk due to a common and often overlooked eyesight issue linked to a simple everyday behaviour: talking. Groundbreaking research from Japan has found that engaging in conversation, even casually, can significantly impair a motorist's ability to spot potential hazards.
The Science Behind the 'Blind' Spot
Scientists at Fujita University conducted a controlled study involving 30 participants. They monitored the subjects' eye movements as they tracked visual targets on a screen, a task designed to simulate the rapid, scanning gaze required for safe driving. The participants were tested under three distinct conditions: in silence, while listening to an audiobook, and while answering general knowledge questions aloud.
The results, published in December 2025, were stark. Researchers observed "clear and consistent delays" in two critical areas: how quickly the eyes moved to new targets and how long it took for their gaze to stabilise once focused on an object.
Why Small Delays Create Big Dangers
Associate Professor Shintaro Uehara, who led the study, emphasised the gravity of these findings. "Visual information has been reported to account for 90 per cent of the information required to drive a vehicle, underscoring the importance of high-quality gaze behaviour," he explained.
Professor Uehara issued a clear warning: "Even small delays in eye movement can accumulate during real driving. This can result in slower hazard recognition and delayed physical responses." In practical terms, this means a driver engaged in conversation could be momentarily 'blind' to a pedestrian stepping onto the road or a vehicle braking sharply just seconds ahead.
Experts Echo the Warning for UK Roads
The research has resonated with road safety experts in the UK. Rod Dennis, a spokesperson for the RAC, highlighted how this aligns with their own data. "Talking to passengers or daydreaming are so common that they aren't perceived as big distractions," he said. "But our research shows they are responsible for most of the errors drivers admit to."
Further supporting evidence comes from collaborative work between the University of Washington and the Toyota Research Institute. Their studies into driver interaction with in-car touchscreens found that under increased mental load, such as holding a conversation, drivers exhibited a "hand-before-eye" behaviour over 70% of the time. This means they would begin an action based on memory, then pause mid-movement while waiting for visual confirmation, a dangerous lag in attention.
Additionally, as mental load increased, glances away from the road at screens became shorter but more dangerous. Average off-road looks dropped by more than a quarter, and prolonged glances over two seconds became rare. This was not a sign of safer behaviour, but rather indicated a reduced ability to process visual information during those brief moments, compounding the risk identified by the Japanese team.
The collective message from researchers is unequivocal: maintaining a conversation, a routine part of most journeys, demands cognitive resources that are crucial for scanning the road effectively. This subtle distraction could be compromising the safety of millions of drivers and other road users every day.
