A large chunk of them see relatively similar colors for the same letters — Y usually shows up as yellow; A as red; and B as blue. This is incredible to visualize when you see the graph below ...

Can you spot the letter 'Y' in this video in under 10 seconds? ... Start scanning from one corner or edge of the sea of letters and move your eyes in a pattern (e.g., left to right, ...

The pattern of their paper correspondence follows the same mathematical laws as electronic mail, researchers say. Both scientists were prolific letter writers, using paper, pen and the postal service ...