In the study, researchers used functional magnetic resonance imaging, or fMRI, to observe brain activity in eight humans and two macaques during a visual attention test. The test worked like this: first, the humans and the monkeys had to memorise a piece of clip art, like a green car, for instance. Then, they were told to fixate on a point in the centre of a computer screen (the monkeys received some additional training for this part). As the monkeys and the humans stared at the point, a stream of images popped up in various parts of the screen at a rate of roughly 10 objects per second. The goal was to push a button whenever they saw the green car appear.