Cog­ni­tive per­for­mance can be improved but peo­ple vary in their abil­i­ty to do so. It is not clear yet how to assess who will ben­e­fit the most from train­ing and the cog­ni­tive tests used in the past were not very good at pre­dict­ing this. Dr. Kramer and his col­leagues recent­ly showed that the brain activ­i­ty in…