Eye movement differs in British and Chinese populations

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University of Liverpool

Eye movement differs in British and Chinese populations

The team, working with Sichuan University in Chengdu, China, investigated eye

movements in Chinese and British people to further understanding of the brain

mechanisms that control them and how they compare between different human

populations. They found that a type of eye movement, that is rare in British

people, is much more common in Chinese people, suggesting that there could be

subtle differences in brain function between different populations.

Tests of eye movements can be used to help identify signs of brain injury or

disease, such as schizophrenia and multiple sclerosis, in populations across the

world. Research at Liverpool, however, has shown that within the Chinese

population there are a high proportion of healthy people that exhibit a pattern

of eye movements previously thought to be rare in the absence of injury or

disease. Findings, published in the journal Experimental Brain Research, suggest

that this pattern may not be as effective as a signal of altered brain function,

in every global community, as originally thought.

Working in China and in Britain, the team tested fast eye movements, called

saccades. Participants in the study were asked to respond to spots of light with

their eyes as they appeared suddenly to the right or left of their line of

sight. The reaction time of the eye movements was the key measure that

differentiated between Chinese and non-Chinese groups.

Dr Knox, from the Institute of Ageing and Chronic Disease, explains: " In a

person from any country in the world we would expect the reaction time of fast

eye movements to be approximately a fifth of a second. Very rarely we find some

people with eye movement reaction times that are much shorter than this, at

around a tenth of a second. This, however, is usually assumed to be a sign of an

underlying problem that makes it difficult to keep the eyes pointing where you

would like for a long enough period.

" In our study, as we expected, 97% of British people had the common fifth of a

second delay, and only 3% had the much faster response. In our Chinese group,

however, 30% had the faster, less common response. Our participants were

healthy, with normal vision, and yet the eye movement pattern previously thought

to be rare, was relatively common in Chinese people.

" There could be a number of explanations for this and further investigation is

needed to fully understand why populations differ. It could be that culture -

where we grow up, the education, work and social activities we are exposed to -

influence these particular biological responses even though our physical make-up

is the same.

" The other possibility is that there are basic differences in brain structure

and function that produce the kind of behaviour we identified. Maps of the brain

were developed many years ago and were largely based on European populations.

This became the blueprint for brain structure, but there could be differences

between various populations. "

Scientists are now investigating eye movement in Chinese people born and living

in Britain compared to Chinese populations born in China but now living in

Britain. The study aims to further understanding into the cultural effects on

eye movement behaviour.

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The research is funded by the Royal Society and the National Natural Science

Foundation of China.

Notes to editors:

1. The University of Liverpool is a member of the Group of leading

research-intensive institutions in the UK. It attracts collaborative and

contract research commissions from a wide range of national and international

organisations valued at more than £110 million annually.