A large letter is made of smaller letters. You'll be told to focus on either the BIG letter (global) or the SMALL letters (local), then judge whether it matches a target. Tests global vs. local processing precedence (Navon, 1977).
Very Easy
20 trials, 3s limit, letters: H, S, T
Easy
24 trials, 2.5s limit, letters: H, S, T
Medium
28 trials, 2s limit, letters: H, S, T, E
Hard
32 trials, 1.5s limit, letters: H, S, T, E
Expert
36 trials, 1.2s limit, letters: H, S, E, F, L
Scientific Background
Based on: Navon Hierarchical Letters Task (Navon, 1977) (Navon & undefined, 1977)