"The human brain isn't equipped to concentrate on two things simultaneously," says neuroscientist René Marois, PhD, associate professor of psychology at Vanderbilt University in Nashville. In brain scan studies, Marois found that the prefrontal cortex lights up for a longer time in people performing two mental tasks at the same time. This illustrates how the brain slows down reaction time.
"Despite employing 100 billion neurons to process information at rates as high as 1,000 times a second," Marois says, "the human brain has a crippling inability to do two tasks at once." Small wonder that the American College of Emergency Physicians reports a rise in texting-related emergency room visits. A new British study has found that texting while driving slows reaction time more than being drunk or high. The results can be deadly, as with the California train wreck in September that involved a texting engineer.
Social experts also warn about an eerie disconnect when we're out with our BFFs while texting friends, family, and the office. "There is a certain degree of 'absent presence' associated with the use of mobile phones and other personal media in the presence of others," notes researcher Scott Campbell, PhD, assistant professor of communication studies at the University of Michigan. "People disengage, or pay more attention to the person on the phone than to the people who are physically present."