How early can you call a target's line?
A clay is launched from the trench at a small angle left or right of straightaway, is visible for between 33 and 67 milliseconds, and is then hidden. You call left or right. An adaptive procedure finds the smallest angle you can call at each viewing time. A first result about three minutes in; the full session about 25 minutes. A laptop with a keyboard, a plastic card the size of a driving licence, and a display of 60 Hz or better.