A dead Atlantic salmon, bought at a market and slid into a brain scanner, once appeared to show brain activity while "looking" at photos of people and judging their emotions. The fish was not thinking. The scan, run in 2005 and presented at a 2009 conference, was a deliberate demonstration of how brain-imaging statistics can conjure signals out of noise. Seventeen years later, the salmon is back in circulation, this time invoked by researchers warning that tools used to explain artificial intelligence can fall into the same trap.
