Brain Scanners Can Tell What You're Thinking About (Neural Decoding)

Brain scanners can tell what you're thinking about

In the last few years, patterns in brain activity have been used to successfully predict what pictures people are looking at, their location in a virtual environment or a decision they are poised to make. The most recent results show that researchers can now recreate moving images that volunteers are viewing - and even make educated guesses at which event they are remembering.

Last week at the Society for Neuroscience meeting in Chicago, Jack Gallant, a leading "neural decoder" at the University of California, Berkeley, presented one of the field's most impressive results yet. He and colleague Shinji Nishimoto showed that they could create a crude reproduction of a movie clip that someone was watching just by viewing their brain activity. Others at the same meeting claimed that such neural decoding could be used to read memories and future plans - and even to diagnose eating disorders.

Understandably, such developments are raising concerns about "mind reading" technologies, which might be exploited by advertisers or oppressive governments (see "The risks of open-mindedness"). Yet despite - or perhaps because of - the recent progress in the field, most researchers are wary of calling their work mind-reading. Emphasising its limitations, they call it neural decoding.

The development of 'mind-reading' technologies is raising concerns about who might exploit them. They are quick to add that it may lead to powerful benefits, however. These include gaining a better understanding of the brain and improved communication with people who can't speak or write, such as stroke victims or people with neurodegenerative diseases. There is also excitement over the possibility of being able to visualise something highly graphical that someone healthy, perhaps an artist, is thinking.

So how does neural decoding work? Gallant's team drew international attention last year by showing that brain imaging could predict which of a group of pictures someone was looking at, based on activity in their visual cortex. But simply decoding still images alone won't do, says Nishimoto. "Our natural visual experience is more like movies."

Nishimoto and Gallant started their most recent experiment by showing two lab members 2 hours of video clips culled from DVD trailers, while scanning their brains. A computer program then mapped different patterns of activity in the visual cortex to different visual aspects of the movies such as shape, colour and movement. The program was then fed over 200 days' worth of YouTube clips, and used the mappings it had gathered from the DVD trailers to predict the brain activity that each YouTube clip would produce in the viewers.

Finally, the same two lab members watched a third, fresh set of clips which were never seen by the computer program, while their brains were scanned. The computer program compared these newly captured brain scans with the patterns of predicted brain activity it had produced from the YouTube clips. For each second of brain scan, it chose the 100 YouTube clips it considered would produce the most similar brain activity - and then merged them. The result was continuous, very blurry footage, corresponding to a crude "brain read-out" of the clip that the person was watching.

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Meanwhile, decoding how people plan for the future is the hot topic for John-Dylan Haynes at the Bernstein Center for Computational Neuroscience in Berlin, Germany. In work presented at the conference, he and colleague Ida Momennejad found they could use brain scans to predict intentions in subjects planning and performing simple tasks. What's more, by showing people, including some with eating disorders, images of food, Haynes's team could determine which suffered from anorexia or bulimia via brain activity in one of the brain's "reward centres".

Another focus of neural decoding is language. Marcel Just at Carnegie Melon University in Pittsburgh, Pennsylvania, and his colleague Tom Mitchell reported last year that they could predict which of two nouns - such as "celery" and "airplane" - a subject is thinking of, at rates well above chance. They are now working on two-word phrases.

Their ultimate goal of turning brain scans into short sentences is distant, perhaps impossible. But as with the other decoding work, it's an idea that's as tantalising as it is creepy.

The risks of open-mindedness

The feats of decoding brain scans to predict someone's thoughts are undoubtedly dazzling (see main story), but "neural decoding" techniques are also limited in how they can be applied. Right now, they only work if someone's brain has already been scanned multiple times, and in very specific circumstances. So can we really call this mind reading? And should we worry about potentially creepy uses for such technology?

To some extent it's a question of semantics, but many researchers, including neuroscientist Russell Poldrack at the University of Texas at Austin, say it's clear that the work done to date is a far cry from what most people think of as mind reading, such as predicting whether a terrorist has plans to detonate a bomb on an aircraft.

Yet even if such applications are a very distant possibility, we should start thinking about the ethical issues now, says John-Dylan Haynes at the Bernstein Center for Computational Neuroscience in Berlin, Germany.

Some companies already claim that brain scans can help to pick out liars and determine whether an advert works or not, and there may be some truth in such claims. Haynes says standards are needed to spell out what neural decoding can and cannot reliably do, so as not to erode public trust in the field.

Neuroscientist Jack Gallant at the University of California, Berkeley, agrees. He says that neural decoding could be a double-edged sword. If his hopes for the technology ever come to fruition, he says, the same machine that reads the thoughts of patients with a neurodegenerative disease may well find more nefarious applications at some point.


http://www.newscientist.com/article/mg20427323.500-brain-scanners-can-tell-what-youre-thinking-about.html?full=true

I don't know what to think about this. I'd much rather keep my thoughts to myself, I think.

It would have cut down on a lot of time and expense...;)

Doesn't mean they're not a nice person :silly: