At Newcastle University, Dr Catherine O’Hanlon and Dr Jenny Read have been using an SMI RED50 to track children’s eye movements while they perform an experimental task using a touchscreen. This posed a few technical difficulties;
The touchscreen displaying the stimuli had to be close enough to the child so that small arms could reach it. The touchscreen was mounted on an adjustable arm, making it easy to bring into the right position for each child participant.
The RED unit had to be placed at a good working distance from the eyes in the set-up - on a table underneath and slightly behind the monitor. This meant it was looking up at the child from underneath, at around 70 degrees up from a horizontal axis.
To help keep the child still, we sat them in a car seat mounted onto a chair. We asked the child to keep their head in contact with the back of the car seat while they were solving the task, ensuring that their eyes remained in the right position – i.e. at a distance of 65-cm from the eye-tracker. A pressure-sensitive switch on the head-cushion mounted on the car seat made a warning sound if the child leant forward before the end of the trial. This alerted the child to sit back in position before the next trial begun. We used a five-point calibration, using our own custom code to display animated figures at the target locations, while a recorded voice called the child’s name to attract their attention.
'Children enjoyed the task so much we sometimes found the RED lost their pupils because their eyes were crinkled in a smile! With these techniques, we were able to record reliable eye-movement and touchscreen data from children as young as two'.