Every science has concepts so fundamental they are nearly impossible to define. Biologists agree on what is alive but not on precisely what life is. In physics, matter and energy elude simple definition. To psychologists, consciousness is similarly a fundamental yet slippery concept.

3-1 What is the place of consciousness in psychology’s history?

At its beginning, psychology was “the description and explanation of states of consciousness” (Ladd, 1887). But during the first half of the twentieth century, the difficulty of scientifically studying consciousness led many psychologists—including those in the emerging school of behaviorism (Chapter 7)—to turn to direct observations of behavior. By the 1960s, psychology had nearly lost consciousness and was defining itself as “the science of behavior.” Consciousness was likened to a car’s speedometer: “It doesn’t make the car go, it just reflects what’s happening” (Seligman, 1991, p. 24).

After 1960, mental concepts reemerged. Neuroscience advances linked brain activity to sleeping, dreaming, and other mental states. Researchers began studying consciousness altered by hypnosis, drugs, and meditation. Psychologists of all persuasions were affirming the importance of cognition, or mental processes. Psychology was regaining consciousness.

Most psychologists now define consciousness as our awareness of ourselves and our environment. This awareness allows us to assemble information from many sources as we reflect on our past and plan for our future. And it focuses our attention when we learn a complex concept or behavior. When learning to drive, we focus on the car and the traffic. With practice, driving becomes semiautomatic, freeing us to focus our attention on other things. Over time, we flit between different states of consciousness, including normal waking awareness and various altered states (FIGURE 3.1).

Today’s science explores the biology of consciousness. Evolutionary psychologists presume that consciousness offers a reproductive advantage (Barash, 2006; Murdik et al., 2011). Consciousness helps us cope with novel situations and act in our long-term interests, rather than merely seeking short-term pleasure and avoiding pain. Consciousness also promotes our survival by anticipating how we seem to others and helping us read their minds: “He looks really angry! I’d better run!”

Such explanations still leave us with the “hard problem”: How do brain cells jabbering to one another create our awareness of the taste of a taco, the idea of infinity, the feeling of fright? The question of how consciousness arises from the material brain is, for many scientists, one of life’s deepest mysteries.

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3-2 What is the “dual processing” being revealed by today’s cognitive neuroscience?

Scientists assume, in the words of neuroscientist Marvin Minsky (1986, p. 287), that “the mind is what the brain does.” We just don’t know how it does it. Even with all the world’s technology, we still don’t have a clue how to make a conscious robot. Yet today’s cognitive neuroscience—the interdisciplinary study of the brain activity linked with our mental processes—is relating specific brain states to conscious experiences.

A stunning demonstration of consciousness appeared in brain scans of a noncommunicative patient—a 23-year-old woman who had been in a car accident and showed no outward signs of conscious awareness (Owen, 2014; Owen et al., 2006). When researchers asked her to imagine playing tennis, fMRI scans revealed activity in a brain area that normally controls arm and leg movements (FIGURE 3.2). Even in a motionless body, the researchers concluded, the brain—and the mind—may still be active. A follow-up analysis of 42 behaviorally unresponsive patients revealed 13 more who also showed meaningful, though less than normal, brain responses to questions (Stender et al., 2014). But reanalysis of some of these EEG data found the positive results to be mere muscle twitches (Goldfine et al., 2013). So this research is an unfinished story.

Many cognitive neuroscientists are exploring and mapping the conscious functions of the cortex. Based on your cortical activation patterns, they can now, in limited ways, read your mind (Bor, 2010). They could, for example, tell which of 10 similar objects (hammer, drill, and so forth) you were viewing (Shinkareva et al., 2008).

Some neuroscientists believe that conscious experience arises from synchronized activity across the brain (Gaillard et al., 2009; Koch & Greenfield, 2007; Schurger et al., 2010). If a stimulus activates enough brain-wide coordinated neural activity—with strong signals in one brain area triggering activity elsewhere—it crosses a threshold for consciousness. A weaker stimulus—perhaps a word flashed too briefly to consciously perceive—may trigger localized visual cortex activity that quickly fades. A stronger stimulus will engage other brain areas, such as those involved with language, attention, and memory. Such reverberating activity (detected by brain scans) is a telltale sign of conscious awareness (Boly et al., 2011). How the synchronized activity produces awareness—how matter makes mind—remains a mystery.

Many cognitive neuroscience discoveries tell us of a particular brain region that becomes active with a particular conscious experience. Such findings strike many people as interesting but not mind blowing. (If everything psychological is simultaneously biological, then our ideas, emotions, and spirituality must all, somehow, be embodied.) What is mind blowing to many of us is the growing evidence that we have, so to speak, two minds, each supported by its own neural equipment.

At any moment, you and I are aware of little more than what’s on the screen of our consciousness. But beneath the surface, unconscious information processing occurs simultaneously on many parallel tracks. When we look at a bird flying, we are consciously aware of the result of our cognitive processing (“It’s a hummingbird!”) but not of our subprocessing of the bird’s color, form, movement, and distance. One of the grand ideas of recent cognitive neuroscience is that much of our brain work occurs off stage, out of sight. Perception, memory, thinking, language, and attitudes all operate on two levels—a conscious, deliberate “high road” and an unconscious, automatic “low road.” The high road is reflective, the low road is intuitive (Evans & Stanovich, 2013; Kahneman, 2011). Today’s researchers call this dual processing. We know more than we know we know.

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If you are a driver, consider how you move to the right lane. Drivers know this unconsciously but cannot accurately explain it (Eagleman, 2011). Most say they would bank to the right, then straighten out—a procedure that would actually steer them off the road. In reality, an experienced driver, after moving right, automatically reverses the steering wheel just as far to the left of center, and only then returns to the center position. The lesson: The human brain is a device for converting conscious into unconscious knowledge.

Or consider this story, which illustrates how science can be stranger than science fiction. During my sojourns at Scotland’s University of St. Andrews, I [DM] came to know cognitive neuroscientists David Milner and Melvyn Goodale (2008). A local woman, whom they call D.F., suffered brain damage when overcome by carbon monoxide, leaving her unable to recognize and discriminate objects visually. Consciously, D.F. could see nothing. Yet she exhibited blindsight—she acted as though she could see. Asked to slip a postcard into a vertical or horizontal mail slot, she could do so without error. Asked the width of a block in front of her, she was at a loss, but she could grasp it with just the right finger–thumb distance. Likewise, if your right and left eyes view different scenes, you will only be consciously aware of one at a time. Yet you will display some blindsight awareness of the other (Baker & Cass, 2013).

How could this be? Don’t we have one visual system? Goodale and Milner knew from animal research that the eye sends information simultaneously to different brain areas, which support different tasks (Weiskrantz, 2009, 2010). Sure enough, a scan of D.F.’s brain activity revealed normal activity in the area concerned with reaching for, grasping, and navigating objects, but damage in the area concerned with consciously recognizing objects.¹ (See another example in FIGURE 3.3.)

How strangely intricate is this thing we call vision, conclude Goodale and Milner in their aptly titled book, Sight Unseen. We may think of our vision as a single system that controls our visually guided actions. Actually, it is a dual-processing system. A visual perception track enables us “to think about the world”—to recognize things and to plan future actions. A visual action track guides our moment-to-moment movements. Some scientists have questioned whether blindsight patients are utterly without conscious vision (Himmelbach et al., 2012; Overgaard, 2012). But the big idea—that human perceptions, memories, thinking, language, and attitudes operate on both conscious and unconscious levels—stands as one of the great insights of today’s cognitive neuroscience.

The dual-track mind also appears in a patient who lost all of his left visual cortex, leaving him blind to objects and faces presented on the right side of his field of vision. He nevertheless can sense the emotion expressed in faces, which he does not consciously perceive (De Gelder, 2010). The same is true of normally sighted people whose visual cortex has been disabled with magnetic stimulation. Such findings suggest that brain areas below the cortex are processing emotion-related information.

People often have trouble accepting that much of our everyday thinking, feeling, and acting operates outside our conscious awareness (Bargh & Chartrand, 1999). We are understandably biased to believe that our intentions and deliberate choices rule our lives. But consciousness, though enabling us to exert voluntary control and to communicate our mental states to others, is but the tip of the information-processing iceberg. Being intensely focused on an activity (such as reading this chapter, we’d love to think) increases your total brain activity no more than 5 percent above its baseline rate. And even when you rest, “hubs of dark energy” are whirling inside your head (Raichle, 2010).

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Here’s another weird (and provocative) finding: Experiments show that when you move your wrist at will, you consciously experience the decision to move it about 0.2 seconds before the actual movement (Libet, 1985, 2004). No surprise there. But your brain waves jump about 0.35 seconds before you consciously perceive your decision to move (FIGURE 3.4)! The startling conclusion: Consciousness sometimes arrives late to the decision-making party.

That inference has triggered more research and much debate. Does our brain really make decisions before we know about them? If so, is free will an illusion? Using fMRI scans, EEG recordings, or implanted electrodes, some studies seem to confirm that brain activity precedes—and helps predict—people’s decisions to press a button or to choose a card in a simplified poker game (Carter et al., 2012; Fried et al., 2011; Soon et al., 2008). However, other studies indicate that brain activity continuously ebbs and flows, including during the experiments’ predecision phase—regardless of whether the decision is made and executed (Schurger et al., 2012). The actual decision to move occurs when the brain activity crosses a threshold, which happens to coincide with the average “time of awareness of intention to move” (about 0.15 second before the movement). This view sees the mind’s decision and the brain’s activity, like a computer’s problem solving and its electronic activity, as simultaneous and parallel.

Running on automatic pilot allows our consciousness—our mind’s CEO—to monitor the whole system and deal with new challenges, while neural assistants automatically take care of routine business. A skilled tennis player’s brain and body respond automatically to an oncoming serve before becoming consciously aware of the ball’s trajectory (which takes about three-tenths of a second). Ditto for other skilled athletes, for whom action precedes awareness. The bottom line: In everyday life, we mostly function like an automatic camera, but with a manual (conscious) override.

Great myths often engage simple pairs: good Cinderella and the evil stepmother, the slow Tortoise and fast Hare, the logical Sherlock Holmes and emotional Dr. Watson. The myths have enduring power because they express our human reality. Dualities are us.

3-3 How does selective attention direct our perceptions?

Unconscious parallel processing is faster than sequential conscious processing, but both are essential. Parallel processing enables your mind to take care of routine business. Sequential processing is best for solving new problems, which requires our focused attention. Try this: If you are right-handed, move your right foot in a smooth counterclockwise circle and write the number 3 repeatedly with your right hand—at the same time. Try something equally difficult: Tap a steady three times with your left hand while tapping four times with your right hand. Both tasks require conscious attention, which can be in only one place at a time. If time is nature’s way of keeping everything from happening at once, then consciousness is nature’s way of keeping us from thinking and doing everything at once.

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Through selective attention, your awareness focuses, like a flashlight beam, on a minute aspect of all that you experience. By one estimate, your five senses take in 11,000,000 bits of information per second, of which you consciously process about 40 (Wilson, 2002). Yet your mind’s unconscious track intuitively makes great use of the other 10,999,960 bits. Until reading this sentence, for example, you have been unaware of the chair pressing against your bottom or that your nose is in your line of vision. Now, suddenly, your attentional spotlight shifts. Your feel the chair, your nose stubbornly intrudes on the words before you. While focusing on these words, you’ve also been blocking other parts of your environment from awareness, though your peripheral vision would let you see them easily. You can change that. As you stare at the X below, notice what surrounds these sentences.

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A classic example of selective attention is the cocktail party effect—your ability to attend to only one voice among many. Let another voice speak your name and your cognitive radar, operating on your mind’s other track, will instantly bring that unattended voice into consciousness. This effect might have prevented an embarrassing and dangerous situation in 2009, when two Northwest Airlines pilots “lost track of time.” Focused on their laptops and in conversation, they ignored alarmed air traffic controllers’ attempts to reach them and overflew their Minneapolis destination by 150 miles. If only the controllers had known and spoken the pilots’ names.

Talk or text while driving, or attend to music selection or route planning, and your selective attention will shift back and forth between the road and its electronic competition. Indeed, it shifts more often than we realize. One study left people in a room free to surf the Internet and to control and watch a TV. On average, they guessed their attention switched 14.8 times during the 27.5 minute session. But they were not even close. Eye-tracking revealed eight times that many attentional switches—120 in all (Brasel & Gips, 2011). Such “rapid toggling” between activities is today’s great enemy of sustained, focused attention.

We pay a toll for switching attentional gears, especially when we shift to complex tasks, like noticing and avoiding cars around us. The toll is a slight and sometimes fatal delay in coping (Rubenstein et al., 2001). About 28 percent of traffic accidents occur when people are chatting or texting on cell phones (National Safety Council, 2010). One study tracked long-haul truck drivers for 18 months. The video cameras mounted in their cabs showed they were at 23 times greater risk of a collision while texting (VTTI, 2009). Mindful of such findings, the United States in 2010 banned truckers and bus drivers from texting while driving (Halsey, 2010).

It’s not just truck drivers who are at risk. One in four drivers admit to texting while driving (Pew, 2011). Multitasking comes at a cost: fMRI scans offer a biological account of how multitasking distracts from brain resources allocated to driving. In areas vital to driving, brain activity decreases an average 37 percent when a driver is attending to conversation (Just et al., 2008). To demonstrate the impossibility of simultaneous multitasking, try mentally multiplying 18 × 42 while passing a truck in busy traffic. (Actually, don’t try this.)

Even hands-free cell-phone talking is more distracting than chatting with passengers, who can see the driving demands, pause the conversation, and alert the driver to risks:

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Most European countries and some American states now ban hand-held cell phones while driving (Rosenthal, 2009). Engineers are also devising ways to monitor drivers’ gaze and to direct their attention back to the road (Lee, 2009).

At the level of conscious awareness, we are “blind” to all but a tiny sliver of visual stimuli. Ulric Neisser (1979) and Robert Becklen and Daniel Cervone (1983) demonstrated this inattentional blindness dramatically by showing people a one-minute video in which images of three black-shirted men tossing a basketball were superimposed over the images of three white-shirted players. The viewers’ supposed task was to press a key every time a black-shirted player passed the ball. Most focused their attention so completely on the game that they failed to notice a young woman carrying an umbrella saunter across the screen midway through the video (FIGURE 3.5). Seeing a replay of the video, viewers were astonished to see her (Mack & Rock, 2000). This inattentional blindness is a by-product of what we are really good at: focusing attention on some part of our environment.

In a repeat of the experiment, smart-aleck researchers sent a gorilla-suited assistant through the swirl of players (Simons & Chabris, 1999). During its 5- to 9-second cameo appearance, the gorilla paused to thump its chest. Still, half the conscientious pass-counting viewers failed to see it. Psychologists have continued to have fun with invisible gorillas. One study of “inattentional deafness” delivered, separately to each ear, a recording of men talking and of women talking. When volunteers were assigned to pay attention to the women, 70 percent failed to hear one of the men saying, over and over for 19 seconds, “I’m a gorilla” (Dalton & Fraenkel, 2012). And when 24 radiologists were looking for cancer nodules in lung scans, 20 of them missed the gorilla superimposed in the upper right FIGURE 3.6—though, to their credit, they were able to see what they were looking for, the much tinier cancer tissue (Drew et al., 2013). The serious point to this psychological mischief: Attention is powerfully selective. Your conscious mind is in one place at a time.

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Given that most people miss someone in a gorilla suit while their attention is riveted elsewhere, imagine the fun that magicians can have by manipulating our selective attention. Misdirect people’s attention and they will miss the hand slipping into the pocket. “Every time you perform a magic trick, you’re engaging in experimental psychology,” says magician Teller, a master of mind-messing methods (2009). One Swedish psychologist was surprised in Stockholm by a woman exposing herself, only later realizing that he had been pickpocketed (Gallace, 2012).

In other experiments, people exhibited a form of inattentional blindness called change blindness. In laboratory experiments, viewers didn’t notice that, after a brief visual interruption, a big Coke bottle had disappeared, a railing had risen, or clothing color had changed (Chabris & Simons, 2010; Resnick et al., 1997). Focused on giving directions to a construction worker, two out of three people also failed to notice when he was replaced by another worker during a staged interruption (FIGURE 3.7). Out of sight, out of mind.

A Swedish research team discovered that people’s blindness extends to their own choices. Petter Johansson and his colleagues (2005, 2014) showed 120 volunteers two female faces and asked which face was more attractive. After putting both photos face down, they handed viewers the one chosen and invited them to explain why they preferred it. But on 3 of 15 occasions, the researchers used sleight-of-hand to switch the photos—showing viewers the face they had not chosen (FIGURE 3.8). People noticed the switch only 13 percent of the time, and readily explained why they preferred the face they had actually rejected. “I chose her because she smiled,” said one person (after picking the solemn-faced one). Asked later whether they would notice such a switch in a “hypothetical experiment,” 84 percent insisted they would.

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Change deafness can also occur. In one experiment, 40 percent of people focused on repeating a list of words that someone spoke failed to notice a change in the person speaking (Vitevitch, 2003). In two follow-up phone interview experiments, only 2 of 40 people noticed that the female interviewer changed after the third question (a change that was noticeable if people were forewarned of a possible interviewer change) (Fenn et al., 2011). Some stimuli, however, are so powerful, so strikingly distinct, that we experience popout, as with the only smiling face in FIGURE 3.9 We don’t choose to attend to these stimuli; they draw our eye and demand our attention. Likewise, when the female phone interviewer changed to a male interviewer, virtually everyone noticed.

The dual-track mind is active even during sleep, as we will see next.