A wearable brain scanner could give computers insight into how hard you're thinking. Conversations between people include a lot more than just words. All sorts of visual and aural cues indicate each party's state of mind and make for a productive interaction. But a furrowed brow, a gesticulating hand, and a beaming smile are all lost on computers. Now, researchers at MIT and Tufts are experimenting with a way for computers to gain a little insight into our inner world. Their system, called Brainput, is designed to recognize when a person's workload is excessive and then automatically modify a computer interface to make it easier.