- 12 photos in the part 1;
- another 12 photos in the part 2.
Then, in part 3 you'll be shown 48 photos & asked if you saw them in:
- part 1 or
- part 2 or
- never saw them at all.
When you have finished the part 3, your results will be given to you.
Click here to begin: http://www.bbc.co.uk/science/humanbody/sleep/tmt/instructions_1.shtml