A sheen is starting to appear on Rocky Blumhagen's forehead, just below his gray hair. He's marching in place in a starkly lit room decked out with two large flatscreens. On both of the TVs, a volcano lets off steam through wide cracks glowing with lava, their roar muffling the Andean percussion and flutes on the soundtrack. Rocky reaches out his left hand, as if to grasp a coin from midair, and one of them disappears with a brrring. "I don't know if I can do it," he says to a guy named Josh sitting nearby in a felt-covered lounge chair. He looks up from his iPad, watching Rocky, age 66, grab, jog, kick, and reach his way through the videogame. "Keep it up," Josh says as the heart monitor in the corner of the screen reads 129.

Maybe the smart phone's hegemony makes perfect evolutionary sense: Humans are tapping a deep urge to seek out information. Our ancient food-foraging survival instinct has evolved into an info-foraging obsession; one that prompts many of us today to constantly check our phones and multitask. A new book The Distracted Mind: Ancient Brains in a High Tech World explores the implications of, and brain science behind, this evolution (some might say devolution). It was written Adam Gazzaley, a neurologist and a professor at the University of California, San Francisco, and research psychologist Larry D. Rosen. Our friends at NPR's Shots blog recently spoke with one of the authors about distraction's impact on productivity.

I even take my phone with me when I head to the restroom, to fire off a few texts. Or I'll scroll through my email when I leave the office for lunch. My eyes are often glued to my phone from the moment I wake up, but I often reach the end of my days wondering what I've accomplished. My productivity mystery was solved after reading The Distracted Mind: Ancient Brains in a High Tech World, by Dr. Adam Gazzaley, a neuroscientist at the University of California, San Francisco, and Larry Rosen, a research psychologist and professor emeritus at California State University, Dominguez Hills. Their book explains why the brain can't multitask, and why my near-obsessive efforts to keep up with email is likely lowering my productive output.

The habit of multitasking could lower your score on an IQ test and cause other cognitive deficits. I even take my phone with me to fire off a few texts when I go to the restroom. Or I'll scroll through my email when I leave the office for lunch. My eyes are often glued to my phone from the moment I wake up, but I often reach the end of my days wondering what I've accomplished. My productivity mystery was solved after reading "The Distracted Mind: Ancient Brains in a High Tech World," by University of California, San Francisco neuroscientist Adam Gazzaley.