In the mind's eye

Scientists are learning how to identify what a patient is looking at. What are the implications?

In 2002, Steven Spielberg released Minority Report, a film in which Tom Cruise plays a detective in a unit which detects and halts crime before it is committed.

Three savants in a bathtub can read the minds of distant citizens and identify when any one is considering something violent. The film was set in 2054.

Well, real life makes science fiction look ordinary. Nature just published the results of a study in which scientists found that by scanning a human brain with an MRI machine and measuring its electrical activity, they were able to identify which out of a given set of images the subject was looking at.

In an environment where airport scanners can strip-search passengers without touching them, and trained security officers stalk the departure halls chatting people up to see if they show undue signs of tension, the potential ramifications of this latest discovery are enormous.

Already commentators are raising the ethical and privacy issues involved, even though sufficiently invasive technology is 30-50 years away, according to Jack Gallant, who led this University of California, Berkeley, study.

With a certain amount of development and better models, he says, scientists will eventually be able to describe what a subject is visualising "" daydreams, memories. However, he says, this requires a much better understanding of the brain and better brain scanners than we now have.

The health implications are broad. Some of the earliest benefits will probably include the ability to assess the impact of a stroke or how well a particular drug is working, and diagnose dementia.

The results are already helping neuroscientists better understand how the visual system works. "You can imagine using this for dream analysis, or psychotherapy," Gallant adds.

If images can be identified in patients' brains, perhaps similar brain "decoding" devices, as the authors of this study call them, will enable doctors and therapists to help patients who have difficulty communicating or processing visual stimuli, such as those suffering from autism, or those who are functionally mute or blind.

More speculatively, if images can be drawn directly from people's brains, this may open up new fields in art. For instance, an artist may be able to translate his or her vision to reality without lifting a finger.