Question: You say you use human volunteers for your experiments - what sort of things happens to the volunteers during the experiments?

Ian van der Linde answered on 21 Jun 2011:

They are usually asked to perform some kind of task that requires vision, like being asked to memorize some symbols, search for a symbol among other irrelevant symbols, distinguish between faces or symbols. While they are doing this, I often measure the position of their eyes with a special machine called an eye-tracker so that I know exactly where they were looking while they were doing the task. Sometimes I measure other things to, but eye-tracking is my most common tool.