Every aspect of our lives plays out in two versions: one conscious, which we are constantly aware of, and the other unconscious, which remains hidden from us. Over the past two decades, researchers have developed remarkable new tools for probing the subliminal processes of our unconscious mind. This explosion of research has led to a sea change in our understanding of how the mind affects the way we live. As a result, scientists are becoming increasingly convinced that how we experience the world - our perception, behavior, memory, and social judgment - is largely driven by the mind's subliminal processes and not by the conscious ones, as we have long believed.
As neuroscientists have probed the human brain, they have catalogued a collection of many parallel modules, with complex interactions, most of which operate outside consciousness. Our subliminal mental processes operate outside awareness because they arise in these portions of our mind that are inaccessible to our conscious self; their inaccessibility is due to the architecture of the brain, rather than because they have been subject to Freudian motivational forces like repression.
We all make personal, financial and business decisions, confident that we have properly weighed all the important factors and acted accordingly - and that we know how we came to those decisions. But since we know only our conscious influences, we have only partial information. As a result, our view of ourselves and our motivations, and of society, is like a jigsaw puzzle with most of the pieces missing. We fill in blanks and make guesses, but the truth about us is far more complex and subtle than that which can be understood as the straightforward calculation of conscious and rational minds.
We perceive, we remember our experiences, we make judgments, we act - and in all of these endeavors we are influenced by factors that we aren't aware of. The truth is that our unconscious minds are active, purposeful, and independent. Hidden they may be, but their effects are anything but, for they play a critical role in shaping the way our conscious minds experience and respond to the world.
Leonard Mlodinow is the author of Subliminal: How Your Unconscious Mind Rules Your Behavior [Pantheon, $25.95]
Here are some examples of the power of the subconscious mind:
Faces play a special role in human behavior. As a result there is a discrete part of the brain - the fusiform face area - that is used to analyze faces, and much of the processing is outside our awareness. Look at these photos of President Barack Obama. The top pair looks like two upside-down shots of the President, but the photo on the left of the right-side up pair looks horribly distorted. In reality the bottom pair is identical to the top pair, except that the top photos have been flipped. Your brain devotes special attention (and neural real estate) to faces - but not upside down faces, since we rarely encounter those, except when performing headstands in a yoga class. That's why we are far better at detecting the distortion on the face that is right-side-up.
How do I love thee? Elizabeth Barrett Browning felt she could count the ways, but chances are, she couldn't accurately list the reasons. Today we are beginning to be able to do just that - and the answer is surprising. For example, we have a natural subliminal affinity for - and bias toward - anything having to do with ourselves. Have a look at the following table. It shows who has been marrying whom in three states of the Southeastern United States. Listed along the horizontal and vertical axes are the five most common U.S. surnames. The numbers in the table represent how many marriages occurred between bride and groom with the corresponding names. The largest numbers, by far, occur along the diagonal - that is, Smiths marry other Smiths and so on.
The science of the mind has been remade by a tool that emerged in the 1990s, functional magnetic resonance imaging, or fMRI. fMRI offers 3-dimensional pictures of the working brain, inside and out, mapping to a resolution of about a millimeter, the level of activity throughout. To get an idea of what fMRI can do, consider this: scientists can now use data collected from your brain to reconstruct an image of what you are looking at. Look at the pictures below. In each case, the image on the left is the actual image a subject was gazing at, and the image on the right is the computer's reconstruction, based on the fMRI's electromagnetic readings of the subject's brain activity.
We all know how it effects us when a lover strokes our skin, but studies show that even a brief, light touch that we hardly notice - and quickly forget - can exert a powerful unconscious influence on our behavior toward the person who touched us. Touching has been found to increase the fraction of single women in a night club who would agree to a request to dance, the number of people agreeing to sign a petition, and the average tip given servers in a restaurant. We are now beginning to understand how touch works its magic: a particular kind of nerve fiber in people's skin - especially in the face and arms - transmits the pleasantness of social touch. Those nerve fibers are connected directly to areas of the brain associated with emotion.
Pepsi consistently beats Coke in blind taste tests, although people seem to prefer Coke when they know what they are drinking, an effect called the "Pepsi paradox". New brain imaging studies found that an area of the brain called the ventromedial prefrontal cortex, or VMPC, is the seat of the good feelings we experience when we contemplate a familiar brand-name product. And so in 2007, researchers recruited a group of participants whose brain scans showed significant VMPC damage, and also a group whose VMPC was healthy. Those with healthy brains indeed preferred Coke when they knew what they were drinking. But those who had damage to their VMPC - their brain's "brand appreciation" module - preferred Pepsi, just as they did in the blind taste tests. Apparently it is the unconscious warm and fuzzy feeling people have toward the brand Coke that explains the Pepsi paradox.
The experience of feeling socially connected to others starts very early in life. Even 6-month-olds make judgments based on what they observe of social behavior. In one study infants watched as a "climber", a disk of wood with large eyes glued onto its circular "face," started at the bottom of a hill, and repeatedly tried but failed to make its way to the top. After a while, a "helper," a triangle with similar eyes glued on, would approach from further downhill and help the climber with an upward push. Other times a square "hinderer" would approach from uphill and shove the circular disk back down. The infants, unaffected and uninvolved bystanders, copped an attitude toward the hinderer squares: when offered a chance to play with the objects, they avoided the squares, and chose the helper triangles. Flickr photo courtesy of Pink Sherbet Photography
Vested interest plays a powerful unconscious role in determining our "sincere" social judgments. In one experiment researchers randomly assigned volunteers to the role of plaintiff or defendant in a reenactment of a lawsuit. Both sides received documents regarding a real case involving an injured motorcyclist and the driver who hit him. The volunteers were paired up and asked to negotiate their own version of a settlement. They were also offered a cash bonus if they could guess - within $5000 - what the judge had actually awarded the plaintiff. Could they ignore their assigned role as advocates, and make an objective guess? No: On average, the volunteers assigned to represent the plaintiff's estimates were double those made by those assigned to represent the defendant.