Zooming in with the Mind Another clever approach to the “how” of conscious- ness takes a different twist: Stephen Kosslyn found we can use our conscious minds to “zoom in,” camera-like, on the details of our mental images. To demonstrate this, Kosslyn (1976) first asked people to think of objects, such as an elephant or a cat or a chair. Then he asked questions about details of the imagined object (for example, “Is it a black cat?” or “Does it have a long tail?”), recording how long it took for people to answer. He discovered that the smaller the detail he asked for, the longer subjects needed for a response. People required extra time, Kosslyn proposed, to make a closer examination of their mental images.
Both these experiments suggest we consciously manipulate our visual images. And we do so in much the same way that we might manipulate physical objects in the outside world (Kosslyn, 1983). You can try this yourself with the demonstration in the box on the next page, Do It Yourself! Zooming in on Mental Images. As we prog- ress through the chapter, you will learn about other techniques used by neuroscientists to study consciousness and its allied mental processes. First, though, let’s look more closely at some models of the mind.
Models of the Conscious and Nonconscious Minds As psychologists have attempted to study and understand consciousness, several models have emerged that remain useful today. You might recall from Chapter 6 that searching for analogies can be a useful problem-solving strategy. Psychologists have employed a similar strategy in trying to nail down the essence of consciousness by searching for the best metaphor to represent this elusive concept. Let’s look at a few of these models.
Freud’s Levels of Consciousness Sigmund Freud originally suggested a notion many of us take for granted today: that our minds operate on several levels at once. The metaphor he developed as a model for consciousness compared it to the tip of an iceberg, suggesting a much larger presence beneath the surface. Freud saw this larger presence—the unconscious—as a reservoir of needs, desires, wishes, and traumatic memories. Moreover, he believed that processing in the unconscious—outside our awareness—could influence our conscious thoughts, feelings, dreams, fantasies, and actions. A large body of evidence now confirms Freud’s insight that much of the mind lurks and works out of sight, beneath the level of awareness.
The Preconscious Psychologists often use Freud’s term, the preconscious, in referring to memories of events (your birthday last year, for example) and facts (Salem is the
preconscious Freud’s notion that the mind has a special unconscious storehouse for information not currently in consciousness but readily available to con- sciousness. Example: your telephone number is stored in the preconscious.
States of Consciousness
capital of Oregon) that are not conscious but are readily accessible. These memories can cross over to consciousness with relative ease when something cues their recall. Otherwise, they lie in the background of the mind, just beyond the boundary of con- sciousness until needed. Thus, the preconscious, in the modern cognitive sense, is much the same as long-term memory.
Preconscious processing isn’t restricted to the serial, one-thing-at-a-time limi- tation of consciousness. That is, it can search for information in many places at once—an ability called parallel processing. On the other hand, the preconscious lacks the ability consciousness has for deliberate thinking. You might think of the preconscious as a memory storehouse, where the stock is constantly rotated so that the most recently used and most emotionally loaded information is most easily accessed.
The Unconscious A dictionary might define the term unconscious as the absence of all consciousness, as in one who has fainted, become comatose, or is under anesthe- sia. Freud, however, defined the unconscious as a reservoir of primitive motives and threatening memories hidden from awareness. And cognitive psychologists have still another meaning for unconscious that refers to any sort of nonconscious process (in- cluding breathing, turning your head, etc.) produced in the brain. Pulling these notions together, we will define the unconscious as a broad term that refers to many levels of processing below the level of awareness. These can range from preconscious memory to brain activity that controls basic body functions to the processes that operate in the background when we form a perception, say, of a table or a comment made by a friend. Such unconscious processes can be subtle—perhaps leading, without our realization, to anxiety or depression (Kihlstrom, 1987).
You can get some idea of how unconscious processes can affect us if you think about how you often follow a familiar route to work or school without apparent thought—even when you are driving! Unconscious processing can also be studied in the laboratory, as you will see in the following demonstration. Try filling in the blanks to make a word from the following stem:
unconscious In classic Freudian theory, a part of the mind that houses emotional memories, desires, and feelings that would be threatening if brought to consciousness. Many modern cognitive psychologists, however, view the unconscious in less sinister terms, as including all nonconscious mental processes.
Ask a friend to close his or her eyes and imagine a house. Then ask your friend to describe the color of the roof, the front door, and doorbell button. Using a watch or clock that displays seconds, record the amount of time it takes to get each answer. Based on Kosslyn’s research, which item would you predict would require the longest response time? The shortest?
You will probably find that the smaller the detail you ask for, the longer it takes your friend to respond. Kosslyn interpreted this to mean that people need the extra time to “zoom in” on a mental image to resolve smaller features. In other words, we examine our mental im- ages in the same way that we examine physical objects in the external world in order to perceive the “big picture” or the details.
How Is Consciousness Related to Other Mental Processes?
Using a technique called priming, psychologists can influence the answers people give to such problems—without their being conscious that they were influenced. In the example just given, there are a number of possible ways to complete the word stem, including defend, defeat, defect, defile, deform, defray, and defuse. We don’t know for sure what your answer was, but we did set you up to think of the word define. How? We deliberately “primed” your response by using the word define several times in the previous paragraph. (There is no certainty, of course, that you would respond as predicted—merely an increased probability.) With methods such as this, psychologists have a powerful tool for probing the interaction of conscious and unconscious processes.
James’ Stream of Consciousness William James offered a different metaphor for consciousness, likening ordinary waking consciousness to a flowing stream carrying ever-changing sensations, perceptions, thoughts, memories, feelings, motives, and de- sires. This “stream of consciousness” includes awareness of ourselves and of stimula- tion from our environment. According to James, it can also include physical sensations from within, such as hunger, thirst, pain, and pleasure.
Part of James’ theory was somewhat similar to Freud’s distinction between the con- scious and the preconscious. For James, consciousness had two levels: an area of focus, which included whatever we are attending closely to at any given time, and a peripheral consciousness encompassing the feelings and associations that give meaning and context to our focus. So, for example, when you attend the wedding of a friend, your focus is on the couple getting married and the guests with whom you are interacting. The feelings you have about the marriage, all the things you know about what led the couple to this pivotal moment in their lives, and whatever other memories the event triggers for you are all part of the peripheral conscious, like the supporting actors in a drama. In this way, we might use vision as another metaphor to describe James’ model of consciousness: Like our peripheral vision, our peripheral consciousness is not the subject of our focus, but lends meaning and context to it.
The Modern Cognitive Perspective The final metaphor we offer for consciousness comes from cognitive psychology. The computer metaphor likens consciousness to the information and images that appear on a computer screen, while nonconscious processes are like the electronic activity behind the scenes, deep inside the computer. Most of the time, our nonconscious machinery quietly operates in parallel with consciousness, but occasion- ally a nonconscious motive or emotion becomes so strong it erupts into consciousness— as when a peculiar odor associated with an emotional memory suddenly brings that emotion to the forefront, or when a growing hunger drive bursts into awareness.
All these metaphors can help us grasp the nature of consciousness, and we will re- turn to them periodically throughout the chapter as we develop our understanding of this fascinating process. Before leaving this section, though, let’s ask one more impor- tant question: Why is consciousness important?
What Does Consciousness Do for Us?
At this moment, your consciousness is focused on these words, written in black letters on a white page. But the words don’t stand alone. Like James suggested in his discus- sion of peripheral consciousness, the words also have meaning, which flows through consciousness as you read. You can, of course, shift the spotlight of your attention to something else—music in the background, perhaps—and, as you do so, the words on the page slip into the fringes of awareness. You may be moving your eyes across the page, but the meaning does not really register. (Every student has had this experience.)
Now, if we can have your attention again, we’d like to remind you that conscious- ness has many functions. Three especially important ones were illustrated by the sce- nario in the previous paragraph (Solso, 2001; Tononi & Edelman, 1998):
• Consciousness restricts our attention. Because consciousness processes information serially, it limits what you notice and think about. In this way, consciousness
Both James and Freud theorized that we have two levels of consciousness. The focus of our consciousness, like the focus of our attention on the singer in the spotlight, takes center stage. Equally important, however, is what James called our peripheral conscious: Just as the band adds richness to the singer’s performance, our peripheral consciousness adds rich contextual detail to our area of focus.
William James spoke of the “stream of consciousness,” which portrayed con- sciousness as an active, ever-changing process. (Courtesy Susan Dupor.)
States of Consciousness keeps your brain from being overwhelmed by stimulation. Unfortunately, the one-thing-at-a-time property of consciousness will not let you concentrate on what you are reading when you shift your attention to music playing in the background.
• Consciousness provides a mental “meeting place,” where sensation can combine with memory, emotions, motives, and a host of other psychological processes in the process we have called perception. Consciousness, then, is the canvas on which we customarily create a meaningful picture from the palette of stimula- tion offered by our internal and external worlds. This is the aspect of conscious- ness that links meaning to words on a page or connects the emotion of joy to the sight of an old friend’s face. Indeed, neuroimaging research indicates that the essence of consciousness is to make linkages among different parts of the brain (Massimini et al., 2005). Consciousness, therefore, lies at the very heart of cognition.
• Consciousness allows us to create a mental model of the world—a model we can manipulate in our minds. Unlike simpler organisms, consciousness frees us from being prisoners of the moment: We don’t just react reflexively to stimulation. Instead, we use a conscious model of our world that draws on memory and fore- thought, bringing both the past and the future into awareness. With this model, we can think and plan by manipulating our mental world to evaluate alternative responses and imagine how effective they will be. It is this feature of conscious- ness that, for example, helps you make associations between concepts in this text and your own experiences, or keeps you from being brutally honest with a friend wearing clothes you don’t like.
These three features—restriction, combination, and manipulation—apply in varying degrees to all states of consciousness, whether dreaming, hypnosis, meditation, a drug- induced state, or our “normal” waking state. But what about the condition known as a coma: Where does it fit into our study of consciousness?
Coma and Related States The general public profoundly misunderstands what it means to be in a coma. This misunderstanding stems, in part, from a few highly publicized and emotional cases that provoked heated discussion about the ethics of discontinuing life support in se- verely brain-injured patients (Meyers, 2007). The flames are fanned, too, by reports of “miraculous” recoveries. So what are the facts?
Comas are not stable, long-term states. Rather, they usually last only a few days— up to about two weeks—after brain injury. In a comatose state, patients lack the nor- mal cycles of sleep and wakefulness, their eyes usually remain closed, and they cannot be aroused. Those who improve transition to a minimally conscious state, during which they may have limited awareness and a functioning brain. Recovery is usually gradual (National Institute of Neurological Disorders and Stroke, 2007). Those who do not improve deteriorate into a persistent vegetative state. In this condition, they may open their eyes periodically, and they pass in and out of normal sleep cycles, but they have only minimal brain activity and basic reflexes. Chances for full recovery from a persistent vegetative state are slim.
But diagnosis of a persistent vegetative state is sometimes inaccurate, as the measurement of brain activity is not a perfect science. And such a mistake could potentially be fatal when the diagnosis is used to make decisions about whether or not to continue life support. Promising new brain imaging techniques are being discovered, however, that can more accurately identify the level of brain activ- ity and awareness in patients who appear to be in persistent vegetative states. Advances in PET and MRI technology have recently enabled researchers to predict successfully which patients in persistent vegetative state would improve and tran- sition into minimally conscious states (Owen et al., 2009). Stay tuned for further developments.