Oh Doctor Freud, Oh Doctor Freud, how we wish that you'd been otherwise employed!
?Doctor Freud," David Lazar, 1951
It can be difficult to deal with the psychologically, philosophically, and historically laden terms such as conscious and unconscious that we use to describe aspects of the way our minds work. In an engineering context, it is useful to work with the more limited concepts of the cognitive conscious and the cognitive unconscious. More accurate would be the terms empirical conscious and empirical unconscious, but Kihlstrom's more euphonic coinage has priority (Cohen and Schooler 1997, p. 137). Understanding that we possess these two distinct sets of limited mental abilities and understanding how they work in relationship to human-machine interfaces is as essential to designing interfaces as is knowing the size and the strength of the human hand when we are designing a keyboard.
Here is a first-cut definition: Unconscious mental processes are those of which you are not aware at the time they occur. The cognitive unconscious is not the seething, mythic creature of Freudian psychology but rather a phenomenon that you can demonstrate with a straightforward experiment, which you will be asked to try shortly. Although a growing mountain of books discusses the questions and paradoxes of consciousness, following the approach taken in Bernard J. Baars's A Cognitive Theory of Consciousness (1988) a book that has broadly informed this chapter helps us to avoid the dilemmas and to deal only with what we can observe directly and produce concretely. As Baars says in his preface, "one time-honored strategy in science is to side-step philosophical issues for a time by focusing on empirically decidable ones." Cognetics is a practical discipline. Although theoretical studies can be illuminating and eventually may lead to firm and practical results, we avoid them until they do. (Analogously, although a study of human bone growth can inform ergonomics, such a study would fall within the purview of physiology rather than of ergonomics itself.)
Consciousness and Models of the Mind
In following Baars's useful treatment of the cognitive properties of consciousness, it is not necessary also to subscribe to his theory of mind, which uses contemporary digital computer structures as models. I am leery of that approach, especially because throughout the ages, thinkers have borrowed the latest technology as models for understanding humans only to abandon or to limit the models when technology advanced.
Don Norman, a cognitive psychologist who is especially conversant with computers, spoke of the mind in terms of computational units (Norman 1981). J. R. Anderson, beginning in 1976, based his model of mental operations on productions a tool prominent at the time for describing the syntax of computer languages (Anderson 1993). Although the analogies are usually enlightening, some scholars tend to overapply the metaphor of the moment. I predict a flowering of psychological theories in the next few years with the client/server architecture, the Internet, and the World Wide Web with its hypertext links and browsers appearing as models for how certain aspects of the mind work.
We must monitor this tendency carefully lest we reify the analogies without neurophysiological support. In the seventeenth century, the universe and its denizens were often spoken of in terms of clockwork (Dijksterhuis 1961, p. 495); with our present understanding of both clockwork and organisms, however, this metaphor has become pallid. In the nineteenth century, the metaphor of the steam engine permeated many philosophical musings on human function; now we know that the analogy's value is limited primarily to explaining metabolism, insofar as the metabolic system is a heat engine.
Two popular books that consider the subject of consciousness are Roger Penrose's The Emperor's New Mind (Penrose 1989) and Daniel Dennett's Consciousness Explained (Dennett 1991). These treatments, however fascinating to read, unfortunately turn out to be of no use in the design of human-machine interfaces. Without direct evidence of functional parallelism in hand, it is wise to avoid taking computer-brain metaphors too literally.
Because concerns about what is conscious and unconscious usually seem remote from our workaday world, let us tangibly demonstrate their reality in your life by means of a question: What is the final character in your first name? Until you read the previous sentence, you were probably not thinking about this alphabetic character and its relationship to your name. You know and have long known what that character is and where in your first name it lies, but you were not paying attention to that knowledge. You were not thinking of it; you were not considering it. Or, to use our preferred terminology, you were not conscious of it. The information was not being accessed, yet you could recover it on demand. We will call that place from which the character was fetched the cognitive unconscious. The cognitive unconscious may not be a physical place, although it must be represented by physical phenomena in the brain. To help dispel the notion that the unconscious or conscious must be places in the brain which is different from the notion that they might be we can think of possible alternative mechanisms. For example, when you became aware, or conscious, of the alphabetic character, this becoming might have been a change of state. Alternatively, perhaps our brains use a pointer mechanism, and a pointer was changed while the memory or thought was left where it was in your brain. It is possible that thoughts and memories could be distributed, like a holographic record of an image.
We could consider other mechanisms or descriptions, but we have no need to do so. For our purposes, all we need is to acknowledge that you were not conscious of the character at one moment and were conscious of it at another moment. I use a positional metaphor from time to time, speaking of a thought as moving from the conscious to the unconscious or back, but you should not think of this verbal convenience as denoting a model of how the brain works. (Research into the physical brain may show such a model to be valid, but that is not our concern here.)
When I use the terms conscious and unconscious in this book, I will generally intend them as abbreviations for the cognitive conscious and the cognitive unconscious. When you did think about the final character in your first name a thought triggered by a sentence in this book that thought became part of your conscious awareness. This change of state of your thought, from unconscious to conscious, demonstrates that you have at least two forms of knowing. To build a science of cognetics, we must banish solipsism and assume that other humans would make the same observations about their mental processes as you just did about yours.
A stimulus, such as reading a particular portion of this book, can trigger the migration of not only an item of information but also a sensation, a feeling, or another aspect of your memory or knowledge from the unconscious, where it is stored, to the conscious, where you are aware of it. Notice how your clothes feel: where they are tight and where they are loose. Until you came across the sentence that directed your attention to your clothes, you probably were not consciously aware of the various pressures that your clothes were putting on portions of your body. You can also call up memories say, of a recent happy event and perhaps can even retrieve a bit of the accompanying emotion from your cognitive unconscious and can bring the memories into your cognitive conscious. Now pay attention to the feel of this book in your hand if you are reading this text in book form or to the input device that you are using to control your computer if you are reading from a display. I trust that these experiments on your part have convinced you that you have a cognitive unconscious and a cognitive conscious and that a stimulus can bring a mental construct from the former to the latter.
By definition, you cannot experience, or be conscious of, any unconscious process. An unconscious process, such as the one that monitors your bladder pressure, can be a stimulus, whereupon the need to relieve yourself becomes conscious.
A bothersome philosophical question in connection with the previous sentence is: Who is the "you" about whom I am talking? Can I distinguish between you and your conscious? Taking an engineering perspective, I sidestep this question, saying simply that the "you" in this case is the union of your physical self and all of the physical and mental phenomena that your physical self manifests. We do not have to address the question of the possible distinctions among you, your conscious, and your unconscious to understand interface-design principles.
It seems likely that memories or keys to memories are stored in physical places in the brain, because in some cases, direct electrical stimulation of parts of the brain, as is sometimes done during brain surgery, can evoke a memory that is, can make that memory conscious. Stimulating one place may reproducibly call up a particular memory, feeling, or sensation; stimulating another place may reproducibly evoke a different experience. Studies of the brain performed with such techniques as magnetic-resonance imaging (MRI) and positron-emission tomography (PET) are helping researchers to elucidate the physical correlates of various mental activities. These technologies are mentioned because they may, at a future time, be directly helpful in the design and, especially, in the testing of interfaces. For example, there is an inverse correlation between a person's localized glucose uptake an indicator of how much energy the brain is using in a particular physical structure and the ease with which that person uses a tested interface feature. Interface testing in the future may well make increasing use of direct measures of brain activity, but a further exploration of these methods lies outside the scope of this book.
Our examples so far have followed mental constructs from unconscious to conscious. Here is an example moving the other way: A sudden noise or other unexpected event can pull your attention away from what you are doing for example, reading this book and to the question of what caused the sound; the sound of a lamp falling from a shelf (what was your cat doing up there?) is an example. After you return to reading, your knowledge of the event will move from the cognitive conscious to the cognitive unconscious.
There are borderline cases, and there is much that we do not understand about the conscious and the unconscious. For example, you sometimes feel that someone's name is on "the tip of your tongue"; you can almost think of the name, but you cannot quite do so. Sometimes, the memory becomes fully conscious and you recall the name. Other times, the memory remains elusive. Is there a state between the conscious and the unconscious? Have we caught the mind in the middle of "moving" the information about the name from one region of the brain to another? Is an almost remembered name evidence for a link partially formed or intermittently connected, sputtering like a loose electrical contact? Such open questions are interesting, but we do not need to answer them, just as in cosmology, we can understand that the universe is expanding, without having a clue about what happened before the expansion started, that is, before the big-bang event that most cosmologists believe was the raising of the curtain on our universe.
As I have said, I do not want to reify any particular metaphor of how the brain works. However, we cannot avoid building mental models of our brain: We build these models of our brain in our brain, a mind-boggling thought. For the time being, then, picture the conscious and the unconscious as separate compartments. These compartments are more than just different places or states for storing thoughts or memories: They have different ways of interacting with the world and with concepts. As has been elucidated by cognitive psychologists over the past century, the cognitive conscious and the cognitive unconscious have properties beyond our awareness and unawareness of them.
Table 2.1 summarizes the differences between the cognitive conscious and the cognitive unconscious. The table tells us that the cognitive conscious is brought into play whenever you encounter a situation that seems new or threatening and whenever you have to make a nonroutine decision that is, one based on what is happening in the here and now. Only when you are conscious of a proposition can you determine whether it is logically consistent. The cognitive conscious operates sequentially and can consider only one question or control only one action at a time. You can be conscious of only between four and eight distinct thoughts or things at once. Your conscious memory fades in, at most, a few seconds.
The conscious is invoked in branching tasks. It is sometimes difficult to distinguish a branching task from a nonbranching task. For example, braking for a traffic light may be either. It is nonbranching and is handled by the cognitive unconscious if you are simply reacting to a red light by pressing the brake pedal. However, if a light that you are approaching turns yellow, such that you have to decide whether to continue through the intersection without pause or to stop, your cognitive conscious comes into play. While you are learning a task, you may see and react to it as a branching event requiring conscious attention. With repetition, your execution of the task may become nonbranching and automatic. In Section 2-3, we start looking into these properties and their implications for interface design.
Table 2.1. Properties of the Cognitive Conscious and the Cognitive Unconscious
Logic or inconsistencies
Tenths of seconds