Mind Mapping

If you overlook the sensational title from Newsweek’s Mind Reading is Now Possible, there’s something worth pointing out here. Scientists are finding that thoughts and ideas map to predictable patterns in the brain.

Scientists at Carnegie Mellon University showed people drawings of five tools (hammer, drill and the like) and five dwellings (castle, igloo …) and asked them to think about each object’s properties, uses and anything else that came to mind. Meanwhile, fMRI measured activity throughout each volunteer’s brain. As the scientists report this month in the journal PLoS One, the activity pattern evoked by each object was so distinctive that the computer could tell with 78 percent accuracy when someone was thinking about a hammer and not, say, pliers. CMU neuroscientist Marcel Just thinks they can improve the accuracy (which reached 94 percent for one person) if people hold still in the fMRI and keep their thoughts from drifting to, say, lunch.

As always, the results have to be replicated by independent labs before they can be accepted. But this is the first time any mind-reading technique has achieved such specificity. Remarkably, the activity patterns—from visual areas to movement area to regions that encode abstract ideas like the feudal associations of a castle—were eerily similar from one person to another. “This establishes, as never before, that there is a commonality in how different people’s brains represent the same object,” said CMU’s Tom Mitchell.

If what your brain does when it thinks about an igloo is almost identical to what mine does, that suggests the possibility of a universal mind-reading dictionary, in which brain-activity pattern x means thought y in most people. It is not clear if that will be true for things more complicated that pliers and igloos, however. “The more detailed the thought is, the more different these patterns get, because different people have different associations for an object or idea,” says Haynes. “We’re much closer to this than we were two years ago, but still far from a universal mind-reading machine.”