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Figure 2.3: The solid line shows an increase in working memory processing for the assignment. As soon as attention shifts to the phone call, indicated by the dotted line, memory resources devoted to the assignment drop as memory resources are used to begin processing information from the caller.

      Say you are in your office, working intently on your computer to complete an important assignment for the CEO. The rise in the solid line in figure 2.3 shows how your working memory is devoting its full resources to processing the assignment. Recall that working memory has a limited capacity. Your cell phone rings. The caller ID indicates that your spouse is at the other end. You think, “Hmmm, I’d better answer it.” As soon as you do, attention resources shift from your assignment to the phone call. Signals from the emotional brain facilitate this shift because, after all, the caller is your spouse, and there may be emotional consequences later for not answering the call. Notice in figure 2.3 how the solid line (resources associated with your assignment) drops rapidly, while the dotted line—representing the resources dedicated to the phone call—rises quickly. When the call ends, working memory has pushed out much of what you were working on for the assignment to make room for the items discussed in your spouse’s call. Returning to your assignment, you realize that you do not remember much of what you were working on at the time of the call, and you think, “OK, where was I?”

      This dramatic loss of attention occurs every time you switch your focus to another source of information, such as answering a phone call or an email. Researchers call this the task switch cost, and these costs add up. Often, working memory gets fatigued from this constant shifting and pays less attention to new information—another reason why too much information paralyzes working memory. Brain scans confirm how easily nonrelevant stimuli, such as the spouse’s phone call, can disrupt our concentration. Using fMRI, researcher Katherine Moore and her colleagues at the University of Michigan found that irrelevant cues introduced when a person was concentrating on relevant information literally hijacked the attention systems, causing resources to be diverted to processing the unrelated items.⁴ Amazingly, these constant interruptions can have a lasting effect on our brainpower.

       Attempts at Multitasking Can Dumb You Down

      Research studies at the Institute of Psychiatry of King’s College London, led by Glenn Wilson, looked at the mental concentration levels of 1,100 office workers.⁵ They found that excessive use of technology actually reduced workers’ intelligence. Individuals who were distracted by incoming phone calls or emails had an astounding ten-point drop in their IQ—more than twice that found in studies of the impact of marijuana use on intelligence. Participants who had a lack of discipline in handling emails had the largest IQ loss. Many workers had an almost addictive compulsion to reply to each new message, resulting in constant changes in focus and the eventual fatigue of the prefrontal cortex. Their attempts at being more productive were, in reality, seriously undermining their productivity. Curiously, 90 percent of the participants agreed that it was rude to receive and handle messages during office meetings or face-to-face conversations. Nonetheless, about a third of them said that this had become an acceptable practice because they believed their supervisors interpreted their behavior as a sign of diligence and efficiency.

       Attempts at Multitasking Adversely Affect Long-Term Memory

      There is growing research evidence that consistent attempts at multitasking affect our brain’s ability to encode information into long-term memory. Psychologist Karin Foerde and her colleagues at the University of California, Los Angeles used fMRI scans to observe the brains of participants as they were learning and trying to remember numerous tasks.⁶ One group learned their tasks without distractions, whereas the other group had their learning interrupted with distracting beeps—not unlike those we hear from cell phones or arriving emails. Later, the researchers asked both groups to recall what they had learned. The undistracted group was able to recall significantly more of what they learned than the distracted group, an indication that distractions interfere with learning and memory. Looking at brain scans while both groups were engaged in learning revealed that the part of the brain responsible for encoding long-term memories (the hippocampus) was active in the undistracted group but inactive in the distracted group. The researchers concluded that attempts at multitasking change the way we learn and diminish what we remember.

       Attempts at Multitasking Hinder Working Memory in Older People

      One of the more disturbing research findings on how multitasking might affect the brain comes from a study comparing how the working memories of older and younger individuals respond to interruptions in their work. Wesley Clapp, Adam Gazzaley, and their colleagues, neurologists at the University of California, San Francisco, found that attempts at multitasking took a significantly greater toll on the working memory of the older participants (ages sixty to eighty) than the younger ones (in their twenties and thirties).⁷ Their study examined how long it took the participants to remember and refocus on a task after a brief interruption. Older participants found it much more difficult to disengage from the interruption and reestablish contact with their original task. This may partially explain why older folks can walk to the refrigerator and then stand at the door trying to remember what they were going to get or go to the supermarket for bread and come back with twenty other items but not bread.