The military is making telepathic helmets. Sign me up.

It appears researchers at UC-Irvine, University of Maryland and Carnegie Mellon have a DOD grant to investigate the development of "though helmets": 

The devices would harness a person´s brain waves and transmit them as radio waves, where they would be translated into words in the headphones of other soldiers.

I need one of these.


Don't blink -- I'm reading your thoughts


The proposed technology (which they don't expect to be ready for a decade or two) relies on EEG technology -- that is, measuring brain waves. As it happens, this is a method I use to run experiments. It has its limitations.


First off, it only really works if people are sitting still and not moving their eyes. EEG measures electrical activity. Ideally, it measure the brain's electrical activity, but muscles also produce electrical activity and the effects are hundreds of times larger than brain effects. People are working on snazzy new algorithms to factor out the thunderclaps of eye blinks (the huge mountains in this picture are individual blinks).

One-of-a-kind

Another problem is individual variation. While blinks are very easy to see in the raw waveforms, thoughts are hard. For instance, one of the best known EEG effects in language is the N400 -- a broadly-distributed negative deflection around 400 milliseconds after the participant sees a word. Unfortunately, the N400 is so small relative to all the noise in the signal that it's hard to see on a single trial. In a typical experiment, each participant sees 30-40 words (or more), and we average across those trials. Even then, each individual person's N400 looks very different, so we usually have to average across at least a dozen different people to get a good signal.

Thoughts

The bulk of EEG research employs a violation paradigm. We measure the brain's activity when something unexpected happens. For instance, a psycholinguist like myself might compare the two following sentences:

(1) Dog bit the man.

(2) The man bit the dog.

The second sentence is surprising relative to the first, and you can typically see a reasonably large effect in the brain waves (modulo the caveats above). Part of the reason we use violation paradigms is they produce large effects. Trying to compare two perfectly normal sentences is much, much harder.

Other typical effects people can find are differences between function words (e.g., prepositions) and content words (e.g., nouns) -- though, again, this is hard to see on a trial-by-trial basis.

Get me one

There are many, many other obstacles in the way of a mind-reading EEG helmet. That isn't to say that I don't think such a helmet will be built eventually, or that the government is wasting it's money. Technology constantly improves, and setting an on-the-face absurd goal can be excellent motivation.

But I wouldn't start saving up to buy one of your own just yet. Though I'd love one. A helmet that worked that well would make my research go much, much faster.