The use of scanners to read brain signals allowed the researchers to correctly determine which of two images their guinea pigs were looking at 80 per cent of the time. The test is one in a series in which scientists have read minds using Magnetic Resonance Imaging (MRI) scanners, which are normally used in hospitals to detect the flow of blood around the brain using a radiomagnetic field and radio waves.
Dr Stephanie Harrison, who led the study at Vanderbilt University in Nashville, asked six volunteers to look at different images on a screen – one of a circle with almost horizontal lines across it and one of a circle with almost vertical lines across it.
As they were shown the images, monitoring showed that different sides of their brains had lit up.
They were then asked to remember one particular circle and, from looking at the pattern of brain activity, the researchers were able to tell with considerable accuracy which one they were thinking of.
Writing in the journal Nature, Dr Harrison said: “Decoding accuracy greatly exceeded chance-level performance of 50 per cent and proved highly reliable in the six participants.”
While the study does not unlock the secrets of mind-reading or thought prediction, it does allow scientists to determine which parts of the brain are involved in short-term visual memory.
Previously, scientists in California asked volunteers to look at 1,750 images then used MRI scans to correctly judge, in nine out of ten cases, which one they were thinking of.
Lead researcher Dr Jack Gallant warned after the results were published last year: “It is possible decoding brain activity could have serious ethical and privacy implications. We believe that no one should be subjected to any form of brain-reading involuntarily, covertly, or without informed consent.”