“Affective computing is like nuclear power. We have to be responsible in defining how to use it,” said Javier Hernandez Rivera, a research scientist at MIT Media Lab, in 2017. In the two years since, there has been a global proliferation of biometric and affective APIs and off-the-shelf hardware designed to power experiences in millions of stores, apps and homes. But unlike trained researchers—or actual nuclear engineers, for that matter—the new operators of these emerging technologies will be ambitious brand and product managers and agency teams, racing to be first-in-category, to claim awards or to hit revenue goals. That’s how meltdowns happen.