Brain train­ing is now a house­hold expres­sion for many fam­i­lies, cour­tesy of Nin­ten­do. What is less vis­i­ble than Nintendo’s suc­cess is the grow­ing num­ber of sci­ence-based com­pa­nies that aim to train spe­cif­ic cog­ni­tive skills. Posit Sci­ence has been get­ting increas­ing lev­els of atten­tion, includ­ing a PBS Spe­cial. Yet, con­sumers strug­gle to under­stand the poten­tial val­ue…