There are lots of brain devices, and the book has a whole chapter dedicated to them. Most of these brain devices are passive, merely needing to be near the brain to have whatever effect they are meant to have (the chapter discusses in turn: reading from the brain, writing to the brain, telexperience, telepresence, manifesting thought, virtual sex, piloting a spaceship, and playing an addictive game. It’s a good chapter that never got that much love. Check it out.)
Since the vast majority of these devices are activated by, well, you know, invisible brain waves, the most that can be pulled from them are sartorial– and social-ness of their industrial design. But there are two with genuine state-change interactions of note for interaction designers.
Star Trek: The Next Generation
The eponymous Game of S05E06 is delivered through a wearable headset. It is a thin band that arcs over the head from ear to ear, with two extensions out in front of the face that project visuals into the wearer’s eyes.
The only physical interaction with the device is activation, which is accomplished by depressing a momentary button located at the top of one of the temples. It’s a nice placement since the temple affords placing a thumb beneath it to provide a brace against which a forefinger can push the button. And even if you didn’t want to brace with the thumb, the friction of the arc across the head provides enough resistance on its own to keep the thing in place against the pressure. Simple, but notable. Contrast this with the buttons on the wearable control panels that are sometimes quite awkward to press into skin.
Minority Report (2002)
The second is the Halo coercion device from Minority Report. This is barely worth mentioning, since the interaction is by the PreCrime cop, and it is only to extend it from a compact shape to one suitable for placing on a PreCriminal’s head. Push the button and pop! it opens. While it’s actually being worn there is no interacting with it…or much of anything, really.
Head: Y U No house interactions?
There is a solid physiological reason why the head isn’t a common place for interactions, and that’s that raising the hands above the heart requires a small bit of cardiac effort, and wouldn’t be suitable for frequent interactions simply because over time it would add up to work. Google Glass faced similar challenges, and my guess is that’s why it uses a blended interface of voice, head gestures, and a few manual gestures. Relying on purely manual interactions would violate the wearable principle of apposite I/O.
At least as far as sci-fi is telling us, the head is not often a fitting place for manual interactions.