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Tracking pupil dilation could lead to better hearing loss treatment 


Picture of a human eye close up

Pupils dilate when brain is working harder

Minute changes in the dilation of people’s pupils could provide information about how hard the brain is working when listening, says a Bradford academic. 

The information could even be used to help tailor interventions for individuals with hearing loss. 

Ronan McGarrigle, lecturer in psychology at the University of Bradford’s School of Social Sciences (Faculty of Management, Law and Social Sciences), wrote his PhD on ‘pupillometry’, which is a method for examining tiny changes in the size of people’s pupils to understand how this relates to the experience of mental effort during listening. 

The subject forms the basis for a public lecture Ronan is due to deliver, entitled The eyes as a window to the listening brain, as part of the latest Bradford’s Cafe Scientifique season. 

Ronan said: “Pupillometry has been around for some time and there have been many studies that show that when people become aroused or they have to take in more information, their pupils dilate. 

“My research was focussed on speech perception in everyday environments, for example how people react to a conversation in a noisy environment, like a pub, or in a car. One of the ways you can measure that is by looking at how the size of the pupil in your eye increases and decreases. 

“If you put someone in a challenging environment, one where there’s a lot of noise, you will observe a fairly predictable increase in pupil size. This is because the brain is having to work much harder than in quiet listening environments. Somewhere down the line, there is a possibility that this could become a useful clinical tool, perhaps to compare mental effort requirements between two different types of hearing aid.” 

He went on: “The differences may be minute, so small that they cannot be seen by the naked eye, but they could be detected by an eye tracker. At the moment, audiologists rely on basic screening protocols (detecting tones in quiet and speech-in-noise tests) to determine which hearing aids are most suitable for people.” 

The research could also have other applications, such as measuring the impact of noisy classrooms on schoolchildren, and the burden of listening in everyday environments for non-native speakers. 

Ronan McGarrigle

Experimental psychologist Ronan, who is currently lecturing on research methods in Psychology, added: “I think this just shows the breadth of research within the field of psychology and that we’re still very much looking to understand the world we live in and how we interact with it.” 

The eyes as a window to the listening brain lecture will be delivered on July 21, 2022 at 6.30pm as part of the Bradford Cafe Scientifique series of public lectures. 

Ronan’s research papers can be found below: