This may be of interest to those who followed the long debate here on
the senses, proprioception and training:
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Motion perception improves with age
Roxanne Khamsi
Older observers outstrip youngsters at some visual tasks.
As people grow older, their vision can actually get better in some
ways, according to a Canadian study. The findings suggest that
neurological changes could help the elderly to spot small motions in
otherwise uniform scenes.
Part of visual processing in the human brain involves cells that
suppress each other's activity. This allows the mind to focus on a
scene's important features while ignoring trivial regions. But as
people age, these inhibitory interactions seem to weaken.
To explore the effects of this change, researchers tested people
between 18 and 31 years old, and others aged 60 and above. Subjects
viewed a computer screen showing moving, vertical black-and-white
stripes. They then had to decide in which direction the bands were
travelling.
Prompt perspective
Previous studies have shown that, as the number of stripes in view
increases, young people become much worse at identifying their
movement. Scientists think that the stripes' large, stark borders
activate the brains inhibitory mechanisms. The mind starts disregarding
these monotonous forms.
Vision expert Patrick Bennett of McMaster University in Hamilton,
Ontario and his colleagues wanted to know if older people showed the
same drop in performance. To the researchers' surprise, they did not.
With a large part of the screen filled with the high-contrast stripes,
younger people required 100 milliseconds to work out the direction of
movement, and took twice as long for a small patch. But the performance
of older people stayed constant at around 70 milliseconds.
"That's a very odd result because in many, many tasks you find that
older people require more time. It's an exception to the rule," says
Bennett. Reduced brain inhibition might make older observers more
sensitive to visual input that is normally suppressed, he says. The
team reports its results in Neuron1.
It is the high contrast between black and white stripes that produces
this effect, and not the expanding area on the screen showing the
stripes. Both young and older people are faster at identifying the
movement of low-contrast grey stripes when they can see more of them.
The big picture
So might this be an advantage in the real world? Bennett speculates
that older people might find it easier to follow action in sweeping
scenes, such as a sporting event. "If you're watching a football match,
you look at the flow of the players up and down the field. That part
might be easier for older people."
At the moment, however, he and his fellow researchers simply aim to
pinpoint where the related inhibitory pathways act in the brain.
References
Betts L. R. et al. Neuron 45, 361 - 366 (2005).
(release from weekly science news reports via Nature.com)