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Figure 1.1: The three major parts of the brain and the prefrontal cortex.

      Just above the brainstem is the next oldest area, known as the limbic system, responsible for processing emotional information and generating emotional responses. This area is often referred to as the emotional brain. Because emotions play an important role in maintaining family and community bonds, as well as in securing a mate, outside stimuli that contain emotional information have the next highest priority.

      Finally, the last and largest area of the brain to develop (and thus the newest) is the cortex, or the rational brain. It makes up about 85 percent of the human brain’s weight. Most reasoning occurs in the forward part of this region, called the prefrontal cortex, located just behind the forehead. The prefrontal cortex is responsible for solving problems, making decisions, and controlling emotions. Any incoming cognitive information not vital to survival or wrapped in strong emotion ends up here.

      Whenever we respond emotionally to a situation, the limbic system plays a major role. Sometimes the emotional response is so intense that the more rational cognitive processes are suppressed or suspended. We have all experienced situations in which joy, anger, or fear of the unknown overcame our rational thoughts. Such a scene may result in us losing our ability to move (“I froze”) or to speak (“I was dumbfounded”). Alternatively, it can lead us to do or say something that we regret later on when our rational brain perks up and remarks, “I can’t believe you did that!” So how do the information-processing hierarchy and the touchy relationship between our rational and emotional brains explain why consumers who based their choice on feelings were more satisfied with their final selection than those who relied mainly on information? Did emotions take over and the rational brain toss all that information aside? Not exactly.

The Limited Capacity of Working Memory

      Psychologists have known for a long time that our short-term memory (now called working memory), located in the prefrontal cortex, has a limited capacity. Back in the 1950s, George Miller from Princeton University’s psychology department suggested that the maximum number of items an individual could hold in working memory was seven, plus or minus two.³ (Perhaps that limit explains classic heptads, such as the seven deadly sins, seven seas, seven wonders of the world, and seven-digit telephone numbers.) However, recent research by Michael Kane (University of North Carolina, Greensboro), Randall Engle (Georgia Institute of Technology), and others suggests that this number is overstated and that our current capacity is closer to three to four items.⁴ Nonetheless, when working memory capacity is reached, something has to happen.

      Get a pencil and a piece of paper. Stare at the number below for seven seconds, then look away and write it down. Ready? Go.

      3521904

      Compare the number you wrote down to the number above. Chances are high that you got it right. Now, let’s try that again, using another number and the same rules. Stare at the number below for seven seconds, look away, and write it down.

      9237546302

      Check what you wrote down. How did you do this time? Chances are you left out some digits. That’s because your brain treated each digit as a separate item, so your working memory got overloaded and simply ran out of capacity. This can also happen when you include too many variables when making an important business or personal decision. Items can slip out of working memory and not be considered as part of the decision at all. And this might be a good thing.

      Dijksterhuis’ studies found that when people were faced with purchasing decisions involving just a few variables, they took time to mull over the options before deciding and were satisfied with their choice.⁵ For those who made impulsive decisions, regret set in as they soon realized they didn’t really want or like what they bought. The results changed considerably when the purchasing decision involved a large number of variables—for instance, buying furniture or a new car. Working memory could not focus on so much information and often chose to focus on just one variable, such as color or size. The end result was that the longer people analyzed their choices, the less satisfied they were with their purchasing decisions. Who were the most satisfied? Those who didn’t spend much time thinking about all the information and just let their emotional brain make the selection.

      Researchers in this area are not suggesting that the emotional brain entirely co-opts the decision-making process when working memory is overloaded. Rather, they suggest that just a few salient facts and feelings are processed over time below the level of consciousness—in unconscious thought—while the individual is engaged in unrelated conscious activities. Eventually, this unconscious process renders a decision that we recall and act on.

      Exactly what happens in the brain during working memory overload has been the interest of researcher Angelika Dimoka at Temple University’s Center for Neural Decision Making.⁶ She has studied the effects of too much information by working with bidders who are involved in a complex marketing frenzy called combinatorial auctions. These are bidding wars for numerous items that people can buy alone or bundled, such as landing slots at a busy metropolitan airport. The vast number of variables that the bidders need to consider eventually leads to information overload. Dimoka used a brain imaging technique known as functional magnetic resonance imaging (fMRI) to measure brain activity in the prefrontal cortex.

      As the bidders received more and more information, Dimoka noticed that activity in the prefrontal cortex decreased quickly (see fig. 1.2, page 8). Working memory was getting full and rebelling. The bidders began to make dumb mistakes and bad choices because the prefrontal cortex essentially abandoned its role as the reasoned decision maker. Furthermore, without the prefrontal cortex exerting its control over the limbic system, emotions began to run rampant, causing a rise in the bidders’ anxiety and frustration. This combined effect resulted in many bad decisions or no decision at all. Apparently, if a little knowledge is a dangerous thing, too much knowledge can be paralyzing.