What Are You Thinking? Technology Answers Her Question

Scary or sensational? A machine that can look into a man's mind

MRI scans

Scientists have developed a computerised mind-reading technique which lets them accurately predict the images that men are looking at by using scanners to study brain activity. Moreover, it appears the brain activity can be detected and transmitted by cell phone.

The breakthrough by American scientists took MRI scanning equipment normally used in hospital diagnosis to observe patterns of brain activity when a man examined a range of photographs and videos. Then a computer was able to correctly predict in nine out of 10 cases which image men were focused on. Guesswork would have been accurate only eight times in every 1,000 attempts.

The study raises the possibility of the technology being harnessed to visualise scenes from a man's dreams or memory.

Writing in the journal Nature, the scientists, led by Dr Jack Gallant from the University of California at Berkeley, said: "Our results suggest it may soon be possible to reconstruct a picture of a man's visual experience from measurements of brain activity alone. Imagine a general brain-reading device that could reconstruct a picture of a man's visual experience at any moment in time. Women will find this fascinating."

It will inevitably also raise fears that a man's brain could be interrogated against his will, raising the nightmarish possibility of interrogation for "thought crimes".

The researchers say the technique can only be applied to visual images and, to date, the experiments rely on cumbersome MRI scanning equipment. The software decoder itself has to be adapted to each individual. But this could be done through a series of phone calls while the scanning equipment is located in a facility far from the subject.

However the team has warned about potential privacy issues. "It is possible that decoding brain activity could have serious ethical and privacy implications," said Prof Gallant. "We believe strongly that no man should be subjected to any form of brain-reading process involuntarily, covertly, or without complete informed consent."

The technique relies on functional magnetic resonance imaging (fMRI), a standard technique that creates images of brain activity based on changes in blood flow to different brain regions, which, in turn, reflects changes in blood flow to other regions.

The first step is to train the software decoder by scanning a man's visual cortex while he views thousands of images over time. This teaches the decoder how that man's brain codes visual information. The next stage is to take a new set of images and use the decoder to predict the brain activity it would expect if the man were viewing each of them. Finally, the man views images from this second set while being scanned. The software matched their observed brain activity with the predicted activity from the decoder. When using a set of 120 images, the software got it right nine out of 10 times.

Gallant said it will be possible in the future to apply the technology to visual memories or dreams. "The visual hardware is engaged and stuff from memory is downloaded into your visual hardware and then replayed," he said. "We will be able to reconstruct imagery in dreams."

"I think it's a significant advance," said Prof Marcel Just, a psychologist at Carnegie Mellon University in Pittsburgh. "These scientists are finding how the brain codes naturalistic scenes. They understand what a man's brain is saying."

"It's definitely an impressive result," said neurologist Dr Steven Laureys at the University of Liège in Belgium. He said the technique could be useful for understanding the mental state of a man who is in a coma.