The strange thing your eyes do when thinking gets hard
December 28, 2025
The eyes have it: Our blinking gives away how interested we are in an exchange
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The rhythmic action of blinking helps keep our vision sharp. Initially studied only in vision science, blinking is now also recognized as a subtle cue showing how the brain handles attention and resources, even when we are listening. It’s thought that as listening becomes more difficult, we blink less, with each pause indicating sharper focus and alertness.
Concordia University researchers ran two experiments to examine how blinking shifts in response to different kinds of stimuli. The researchers hypothesized that blinks were more than just eye care responses – they may also be small signs that the brain is active. The study’s findings suggest that blinking connects to thinking, helping us tune out background noise so we can focus on one person talking in a noisy room.
Their study found that when we listen harder, we blink less, keeping our eyes open in the moments that matter most, especially when noise makes understanding more difficult.
“We wanted to know if blinking was impacted by environmental factors and how it related to executive function,” said lead author Pénélope Coupal. “For instance, is there a strategic timing of a person’s blinks so they would not miss out on what is being said?”
Two groups of listeners – 21 in the first test, 28 in the second – sat in a silent Montreal lab, 2 m (6.6 ft) from a 35‑inch screen. Wearing eye-tracking glasses, every blink was carefully recorded, with precise start and end times noted, turning eyelids into tiny markers of attention.
In the first test, the 21 individuals listened to 80 sentences with different amounts of background noise, while lighting remained consistent. In the second test, the 28 participants listened to 120 sentences at only two noise levels, quiet and loud, but the lighting changed between dark, medium, and bright.
When we struggle to hear speech in noisy places, our eyes tell a story: blinking slows, with each pause a quiet sign of mental effort. Researchers found this effect is most intense in very bright or very dark settings, where our eyes seem more sensitive to extremes of light, making the drop in blinks sharper than in steady, medium lighting.
“We don’t just blink randomly,” Coupal said. “In fact, we blink systematically less when salient information is presented.”
People blinked less while actively listening to sentences than in the moments before or after, with this suppression most striking in the noisiest settings where speech was hardest to follow. Although blink rates varied widely between individuals – from 10 blinks per minute to as many as 70 – the overall pattern was clear: fewer blinks marked the effort of listening through noise.
The authors noted, “Blinking could serve as a complementary measure to investigate effortful listening.”
Earlier studies on eye behavior mostly looked at pupil size, ignoring blinks. This study rechecked the data and showed that when and how often we blink can point to brain effort. Blink rates are a simple, low‑effort way to measure thinking, both in the lab and in daily life.
Researchers call for deeper studies to see how blink patterns play out in more complex tasks and across different groups of people. They also want to find the exact moment a blink makes us miss sights or sounds, showing how these tiny pauses affect the way we experience the world
The findings are published in the journal Trends in Hearing.
Source: Concordia University
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