A quote from the researchers:
dozen volunteers were shown line drawings of five different types of buildings and five different kinds of tools while their brain activity was monitored by functional magnetic resonance imaging — or fMRI — which measures changes in blood flow. Computers then analyzed the fMRI images — which are taken 60 times a minute — checking 20,000 locations on each image for changes in activity. Patterns emerged, and the computers were able to “learn” which patterns of brain activity were associated with specific images and determine not only whether the person was looking at a picture of a building or a tool, but which tool. Even more significant, the patterns established with the fMRI images were used to identify which of the objects was being viewed by a different set of people. This means that people generally think the same way, and a computer program could conceivably be written to read the minds of most people.
I think that in steps to follow we will discover how people can read each other’s thoughts. And we will be able to measure the first person to know what the second person is thinking about. This will take a couple of decades, but interesting times are on their way.