We’ve all seen them, those colorful images that show how our brains “light up” when we’re in love, playing a video game, craving chocolate, etc. Created using functional magnetic resonance imaging, or fM.R.I., these pictures are the basis of tens of thousands of scientific papers, the backdrop to TED talks and supporting evidence in best-selling books that tell us how to maintain healthy relationships, make decisions, market products and lose weight.

But a study published last month in the Proceedings of the National Academy of Sciences uncovered flaws in the software researchers rely on to analyze fM.R.I. data. The glitch can cause false positives — suggesting brain activity where there is none — up to 70 percent of the time.

70 percent false positives suggest that we really know very little about how the brain works.