The complex art of seeing
Cognitive visual search strategies at Imperial College
Scientists at Imperial College are investigating the mental effort and visual knowledge needed to make sense of complex images. They are using a technology that allows them to plot the movement of the eyes.
Eye movements
Our eyes only see things sharply and in full colour with the small central part of the retina. So our eyes must move to search any scene carefully.
Our eyes move in a particular way fixing on one point on the scene in view, then moving fast and straight to another. We each make a quarter of a million such eye movements every day.
Scientists use eye trackers to measure the movements. One type of eye tracker fits on the head rather like a bulky pair of spectacles. An invisible, harmless infrared beam emitted from the tracker and reflected by the eye gives back a signal which allows the tracker to register the position of the eye.
In this way they can see how a viewer searches a complex image looking, say, for a waving hand in a big crowd.
Understanding experts
Professor Yang and his team at Imperial are using eye-tracking technology to see how the eyes of experts move when tackling visual problems. Experts include people such as radiologists who interpret X-ray photographs.
The scientists hope to gain insight into the way people tackle specialist tasks. They are exploring the links between how people look at things and how they reason about them. The hope is that it will be possible to train the inexperienced to apply the methods of experts. So, for example, trainee radiologists could learn to make diagnoses from X-ray images more quickly.
Applications
There is an interesting possibility that an eye-tracker could be used in place of a keyboard and mouse to interact with a computer. This could make observing virtual reality a much more natural experience.
Another possibility is that the new technology in a car could detect that a driver is in danger of falling asleep and give an alert to wake the driver and prevent an accident.
Submitted by: Professor Guang-Zhong Yang, 17 January 2006
