RACHEL MARTIN, HOST:
Some time ago, a couple of psychologists were having lunch together at a cafe in Harvard Square in Cambridge, Mass. They did what millions of us do as we chat with other people. They put down their smartphones on the table next to them. The host of NPR's Hidden Brain podcast Shankar Vedantam is here to explain what happened next. Shankar, welcome.
SHANKAR VEDANTAM, BYLINE: Hi, Rachel.
MARTIN: I am dying with suspense.
MARTIN: Tell me what happened. Did the phones start ringing?