You No Longer Own Your Face

If 20 people are in a coffee shop, then there are at least 21 cameras: One embedded in each person’s phone and, usually, one tucked high in the corner. What you say may be overheard and tweeted; you might even appear in the background of another patron’s selfie or Skype session. But that doesn’t stop even the most private people from entering coffee shops. They accept the risk inherent in entering a public place.

This notion—of a “reasonable” expectation of privacy—guides researchers hoping to observe subjects in public. But the very idea of what’s reasonable is a complicated one. Faculty at three universities—Duke, Stanford, and the University of Colorado after creating databases of students as they walked through cafes and on college campuses. You might reasonably expect being overheard in a coffee shop, but that’s different from suddenly becoming a research subject, part of a data set that can live forever.