Stimulus => Sensory Memory => Working Memory => Long-Term Memory If you want to sharpen your mental ability, you should train your working memory. Train your working memory with 'NBack'. *NBack:The current answer matches the one from N steps earlier in the sequence. 'NBack for iPad Lite' is Lite Version of 'NBack for iPad'. Full Version: 1'Back --- 10'Back Lite Version: 1'Back --- 2'Back