NEW DELHI, Dec 12: Blinking less in noisy setting could mean the brain is working harder to understand speech, according to a study, hinting that the act of blinking reflects mental effort exerted during everyday listening.
Two experiments, described in a paper published in the journal Trends in Hearing, showed how blinking patterns changed in response to stimuli under differing conditions — changes in lighting did not appear to have an impact.
Researchers from Concordia University in Canada monitored 50 adults in a soundproof room whose eyes were fixated on a cross on a screen. Blinks were recorded with timing as the participants listened to short sentences through headphones, while background noise varied from quiet to loud.
Blinking rates consistently dropped while participants listened to a sentence, compared to the duration immediately before and after, the team found.
Blinking was especially suppressed under noisiest conditions, when speech was hardest to understand, they said.
“Our study suggests that blinking is associated with losing information, both visual and auditory,” co-author Mickael Deroche, an associate professor in the department of psychology at Concordia University, said.
“That is presumably why we suppress blinking when important information is coming,” Deroche said.
In a second experiment, the researchers tested blinking rates at differing levels of background noise in rooms with dark, medium and bright lighting.
Patterns similar to those in the first experiment emerged, indicating that cognitive demands drive the blinking effect, rather than how much light reaches the eye, the team said.
The study “showed that blink occurrence decreased during sentence presentation, with the reduction becoming more pronounced at more adverse SNRs (signal-to-noise ratios)”.
The researchers added previous research that have linked ocular or visual function to cognitive effort focussed on measuring pupil dilation and treated blinks as nuisances to be removed from the data.
The study re-analysed existing pupil dilation data to focus specifically on blink timing and frequency.
The findings provide evidence for how blink rates can be used as a practical, low-burden metric to measure cognitive function in both laboratory and real-world settings, the team said.
“We wanted to know if blinking was impacted by environmental factors and how it related to executive function,” lead author Pénélope Coupal, an honours student at Concordia University’s laboratory for hearing and cognition, said.
“For instance, is there a strategic timing of a person’s blinks so they would not miss out on what is being said?” Coupal said.
The lead author added, “We don’t just blink randomly. In fact, we blink systematically less when salient information is presented.” (PTI)
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