Spot the difference
Rees can tell when your brain sees changes in the world around you even before you notice. Volunteers in his lab try to spot the differences in two near-identical pictures that flash before their eyes. By taking pictures of their brains processing the puzzle, Rees maps the active areas of the brain while they search - and can also pinpoint when they consciously spot the difference.
Go to page 3 to try the puzzle for yourself. See how you move from being unconscious of the change (before you see the difference) to being consciously aware (when you spot it). People with epilepsy should not attempt the test.
| 
| Volunteers are asked to spot the difference between two pictures that flash before their eyes. |
|
