Backtrack

Rules

Backtrack is a position n-back: a cell of the grid lights up every 2.5 seconds. Press “Same” when the lit cell is the same as the one N steps before.

• Three sizes: 1-back (the same as one step before), 2-back, 3-back. A game shows 20 cells plus N, about 30% of them “Same”.
• A right press scores a point, a false alarm takes one away; a missed “Same” costs nothing and scores nothing. On a tie, the mean reaction time on the right presses decides.
• The daily challenge is the same for everybody, renewed at midnight (Paris time); only your first try of the day counts in the standings. The free run draws a new sequence each game; your best score of the day counts.
• With the keyboard: Space or A for “Same”. With a finger: tap the grid or the button.
• Reactions too fast for a hand are kept but not ranked; a perfect game under 375 ms on average waits for an admin’s eye.

Where the n-back comes from

The n-back is a working memory task devised by the psychologist Wayne Kirchner in 1958: keep the last items seen in mind and update them at every step. It became famous with the study of Susanne Jaeggi and her colleagues (2008), who trained it in a dual form, position and sound.

Backtrack makes it a daily challenge, the same for everybody. It is a game, not a medical test: later studies have not shown that training on the n-back raises IQ. You will get better at the n-back, and that is something.