Experiments by University of Michigan at Ann Arbor neuropsychologists showed improved “fluid intelligence,” or Gf, the ability to reason, solve new problems and think in the abstract.

The first part of the “dual n-back” exercise involves small squares on a screen that pop into a new location every three seconds. Volunteers have to press a button when the current location is a duplicate of two views earlier.

For the second part, the volunteers have to simultaneously carry out the same task with letters. Consonants are played through headphones and they have to press a button when they hear one that is the same as that heard two “plays” earlier.