The world's best tennis players believe they succeed because they keep their eye on the ball, but in fact they don't. Research has shown they pick up subtle clues about where a served ball is going to land by arm and racket movements and not from the ball itself.
How scientists could know such a thing comes from studies into eyetracking, the business of discovering exactly where the eye looks when providing visual information to the brain. It is a rapidly developing research area that provides a remarkable meeting house where cognitive scientists, psychologists, sports performance specialists, rehabilitation practitioners and computer scientists can find common ground.
Prof Aidan Moran, director of the Psychology Research Laboratory at UCD and Dr Carol O'Sullivan of the Image Synthesis Group in the Computer Science Department at Trinity College have joined forces to organise a workshop next week to provide a forum for discussions on eye-tracking research.
Individuals from all of the disciplines mentioned above are expected to attend, Prof Moran said, and a website giving details about the workshop has been established at http://isg.cs.tcd.ie/iwet/programme.htm
Eye-tracking is "the use of eye movements as an index of attention", Prof Moran explained and is based on the assumption that a person will "look at what they think is important".
Eye movements can be used as a tool for identifying what the person believes to be most important for understanding a visual context. "Looking is not the same as seeing," Prof Moran explained. "Seeing is a product of the mind," and relates to how the brain processes information from the eyes' visual input. "We see with our minds rather than our eyes."
For this reason both knowledge and experience can influence what our brain believes are the most important visual clues and can therefore influence where specifically we look when our eyes survey a scene.
Prof Moran provided the tennis example which was based on a study of where people who were particularly good at returning powerful serves looked just before the ball arrived. The ball comes so fast the person doesn't have time to be consciously aware of its position.
While the players all said they watched the ball, special measuring devices showed that their eyes rested at the moment of service on their opponent's arm, shoulder or racket. "They didn't even know they were doing this," Prof Moran said.
Interestingly, there is a great difference between where experts look as opposed to novices, he said, a function of both experience and training. "We are unlocking the mysteries of what experts pay attention to. We are interested in what the experts know that makes them experts."
Unusual devices have been developed that allow researchers to record where in a visual field an expert first looks and where their eyes pause. There were two main eye movements, Prof Moran explained, rapid jumps from place to place known as "saccades" after the French verb saccader, to jump, and very brief pauses known as "fixations". Fixations pass in as little as 100 to 150 milliseconds, but seem to be the key moments when the brain takes in the visual information it needs to "see".
Purpose-built helmets are worn by subjects undergoing eye-tracking experiments. These direct infra-red beams at the cornea and reflected infra-red is captured as a signal, and this data is in turn interpreted by a computer. A series of known images are first looked at so the signals arriving at the computer can be calibrated and after that the system is able to identify where exactly the eye is pointed.
As a former official psychologist to the Irish Olympic squad and a specialist in concentration strategies in top athletes, Prof Moran's particular interest is in cognitive sport psychology and so much of the research in his lab relates to sporting contexts.
Ms Alison Byrne in his lab, for example, has compared where expert versus novice equestrian performers look when presented by fences in a computer simulated show-jumping course.
Ms Nicola McGlade is gauging the influence of anxiety on gaze location in expert gymnasts. She has found that fear of physical injury during difficult routines can influence eye movement, directing it more frequently towards cues that signal danger.
In another project, Mr Frank Doyle is studying where people look when confronted by "You-are-here" maps. He has found there is no advantage in using a 3D as opposed to a flat map to help people get about even though such a map gives a truer representation of the terrain.
The eye-tracking workshop takes place on Wednesday May 17th from 9.30 a.m.5.30 p.m. at Lecture Theatre 5 in the Hamilton Building at Trinity College and in the nearby conference room adjoining the O'Reilly Institute.