timothy johnson explains. >> reporter: have you developed your brain to function at optimum capacity? are you using it to its fullest potential? if you need help, there are a wealth of brain-training programs that promise to help your mind work more quickly and efficiently, much like physical fitness workouts for the body. beware, a new study published in the scientific journal "nature" says the brain fitness programs may not live up to their billing. researchers train more than 11,000 subjects on computer- based tasks designed to improve memory, reasoning, planning and visual skills. they found participants did improve on the specific tasks on which they were trained. however, when the subjects were given closely related tasks on which they had not been trained there was no evidence they were able to transfer the skills or effects. researchers argue that without such a transfer there was no true training of the brain. so while doing word or math games, puzzles, teasers, and tests can be fun and stimulating, there's still no conclusive proof that it actually makes you smarter. with th