What is attention?

Introduction

Attention usually refers to concentration on a particular aspect of the external environment, although it is possible to attend to one’s own thoughts and other internal states. The flavor of the typical use of the term is captured in a statement by nineteenth-century German physiologist Hermann von Helmholtz, who noted that an observer who is steadily gazing at a fixation mark can, at the same time, concentrate attention on any given part of the visual field. The point in space to which one is directing one’s eyes and the point to which one is attending thus are not necessarily the same, and one does not have to move the eyes to shift visual attention.

Attention has been of interest for a long time. Helmholtz wrote about attention in an 1850 book on physiological optics. William James, a pioneer in the study of psychology, devoted much space to attention in his book
The Principles of Psychology
(1890), noting that it can be either involuntary and effortless or voluntary and effortful. According to James, attention allows people to perceive, conceive, distinguish, and remember better than they otherwise could. Edward Titchener, in his Lectures on the Elementary Psychology of Feeling and Attention (1908), reinforced this point by stating that attention determines what people are conscious of as well as the clarity of their conscious experience.

Other leading figures from the early history of psychology, such as Wilhelm Wundt, agreed with James that the issue of attention was of great importance. Titchener regarded the prominence of the topic as one of the major achievements of experimental psychology. Interest was maintained through the period following World War I; Karl Dallenbach noted in the late 1920s that more studies had been reported on attention in the preceding three years than in any comparable period in history. After World War II, the study of attention received an even greater boost with the increasing concern over human-machine interactions, especially in the military.

Attention can be drawn automatically (involuntarily and effortlessly) by certain characteristics of stimuli in the environment. These include abrupt brightness changes or vivid colors at particular locations; both intensity and clarity are important. Auditory attention is automatically drawn by changes in pitch or location. Such automatic attentional capture is often termed “bottom-up” or “data-driven.” A person readily attends to familiar stimuli, although these more often invoke voluntary and effortful processing, which is “top-down” or “internally driven.” A person can voluntarily attend to any aspect of the environment he or she chooses.

Attention Selection

How does a person select the things to which to attend? This question leads to a consideration of “early” (before meaning is analyzed) versus “late” selection. In 1958, Donald Broadbent championed the view that selection is made early through a process analogous to filtering incoming information according to its sensory properties. After a brief glimpse, a person can report the identity of items in the environment accurately if a cue indicating which items to report refers to their spatial location, but that person is much less accurate if the cue refers to semantic properties—for example, if it asks for only the letters from a display of several letters and digits intermixed.

Other researchers, such as J. Anthony Deutsch and Diana Deutsch, have argued that people unconsciously analyze all incoming information for its meaning, although selection cannot be made on this basis as easily as on a sensory basis. Support for this process, termed late selection, can be seen in tasks such as naming the ink colors of printed letters. J. Ridley Stroop
found that if a word that is the name of a color is printed in ink that is a different color from the one it names—for example, the word “blue” written in red ink—it takes much longer to name the ink color than if the combination of letters is meaningless, such as a row of red Xs. People cannot avoid reading the word, no matter how hard they try. Thus, word meaning appears to be activated automatically, and a person cannot selectively attend to the color. Nevertheless, if the color to be named appears as a patch, separated in space from the inconsistent color word, color naming is not slowed. Selection of what to attend to thus can be made easily on the basis of location, color, or brightness but not on the basis of meaning.

Visual, Sensory, and Spatial Attention

Attention is necessary because people do not have the capacity to be conscious of all aspects of their environment at once. Questions arise concerning the extent to which people can be conscious of more than one aspect simultaneously and of what aspects they can be simultaneously conscious. Because what is to be attended to can so easily be selected on the basis of its location, these questions often have been posed in relation to whether people can attend to nonadjacent areas simultaneously.

It is important first to point out that the observations of Helmholtz, James, and Titchener have been verified in sensitive laboratory experiments. Subjects gazing at the center of a computer screen were first given information about the spatial location on the screen of a target that would later appear away from fixation. The correct location usually was indicated, but sometimes an incorrect location was indicated. In comparison with instances when no location information was shown, detection of the target was aided by valid information but harmed by invalid information. If the target did not appear in the indicated location, however, detection was better when it appeared near the indicated location than when it appeared farther away. The edges of the attended area are thus vaguely rather than sharply defined. Yet can attention be split between nonadjacent locations? Most research has shown that this is not possible; people cannot attend to two separate areas simultaneously, although a few studies have indicated that they can attend to ringlike areas with attention devoted to the ring but not the surrounding area or the center.

In contrast to splitting visual attention between two separate locations, dividing attention between two different senses is possible. People can, for example, listen (attend) to a conversation while watching (attending to) the road when driving. Nevertheless, unless one of the tasks is very easy or highly practiced, performance still suffers in comparison to when attention is dedicated to one sense.

Directing attention on the basis of spatial location appears to be very important. Ulric Neisser described the visual determination of what is present as occurring rapidly in two stages. The first he called “preattentive” because it involves only a rough global analysis of information in the entire visual field, before attention is directed to any one location. People can detect simple visual features such as color, brightness, and the direction in which a straight line points on the basis of preattentive analysis. More precise determination of combinations of these simple features requires what is called focal attention, in which attention is focused on particular spatial locations containing the preattentively detected simple features. For example, seeing that a line in a particular orientation is of a certain color requires focal attention. Without it, a person could tell that the color is present somewhere, and that a line of that orientation is present somewhere, but not that the line is of that color. Focal attention is required to combine simple features. This process has been termed feature integration theory, and focused attention is described as the metaphorical glue that binds separate features into a unitary object.

Feature integration theory has received experimental confirmation in the work of Anne Treisman and her colleagues. They found that when focal attention is diverted or cannot be applied because of an interfering task, simple features are often matched incorrectly to produce what they termed “illusory conjunctions.” For example, when a red horizontal line and a green vertical one are shown, in the absence of focal attention, a subject is likely to be conscious of the horizontal line as green and the vertical line as red.

Use of Schemata

A person can direct attention on bases other than a spatial one. That is, even overlapping shapes can be selectively attended. Neisser has described a study in which a basketball game and a hand-slapping game were shown simultaneously in outline form in the same location on a television screen. Observers could attend to only one game and were largely unaware of events occurring in the unattended game, but they were just as able to indicate each occurrence of some event in the game being attended, such as a throw of the ball from one player to another, as they were when that game was shown alone. The inability to divide attention between two games is due to expectations inherent in the way people understand and mentally represent each game. These mental representations are called schemata. Through them, attention has its effects as an alerting and sustaining process whereby receptivity to certain information can be maintained over the short or long term.

One additional phenomenon involves what Colin Cherry referred to as the “cocktail party phenomenon.” The setting is a cocktail party or any gathering where people are engaged simultaneously in different conversations. A person can listen selectively to one conversation and apparently not be conscious of others. Auditory attention therefore seems fully focused on only one conversation. However, the listener might hear his or her name mentioned in any one of a number of other conversations and immediately shift attention to it. How can people attend fully to one source of information, yet simultaneously be sensitive to important information from other sources? Can their attention be focused and yet divided among a number of possible sources of information at the same time? The answer lies in the fact that stimuli outside the focus of attention are sometimes processed to the level of meaning, especially if they correspond to active and important schemata such as one’s name.

Practical Uses of Research

Understanding how attention operates makes it possible to design environments that enable people to better attend to important characteristics. For example, hunters often are cautioned to wear a piece of clothing colored “blaze orange.” A bright color is a simple feature that draws attention automatically. Another hunter’s attention will be drawn to the blaze orange, and focusing attention on the color will allow it to be conjoined with other simple features, such as shape. The second hunter thus will almost immediately be conscious of the hunter wearing the blaze orange as a hunter and will be unlikely to misperceive this hunter as game (in addition, the color of game is never blaze orange). The same principle is applied when emergency vehicles such as fire trucks are painted bright red or yellow.

Principles stemming from basic research on attention have been applied in the development of what is known as head-up displays (HUDs) in aircraft such as helicopters. Typically, a pilot faces a windscreen through which the environment can be seen, with a cluster of instruments designating altitude, speed, and so on nearby. With this configuration, the pilot must look away from the windscreen and at the instruments to check them. As helicopters are capable of traveling at high speeds and often are flown close to the earth and to objects into which they might crash, it is important that looking away from the windscreen be minimized. In a HUD, the data from the instruments is projected onto the windscreen so that the pilot can see the information without having to divert his or her eyes from the windscreen.

Can the pilot attend to the instruments and the environment outside the windscreen simultaneously? They spatially overlap and thus are visible at the same time, yet studies of attention indicate that the pilot cannot attend to them both at once. The experiment described by Neisser in which two games were superimposed on a screen is relevant here. An observer could attend to one game or the other but not to both at the same time. This does not mean that HUDs are without value. Attention can be directed from the instruments to the environment or vice versa without the pilot moving his or her head or eyes, and either type of physical movement is much more time consuming than a relatively rapid shift of attention.

Shadowing

One popular laboratory task is to have listeners “shadow” material presented to them. In shadowing, the listener hears a series of words spoken at a normal conversational rate and tries to repeat aloud each word as it is heard. The task is difficult, and subjects must devote considerable attention to the shadowing. Often a listener is asked to shadow material played with a tape recorder to one ear while different material is played by another tape recorder to the other ear (earphones are used). Certain characteristics of the material not being shadowed can be varied. After the task, the listener can be asked a number of questions regarding what he or she was conscious of in the unshadowed message.

Consistent with Cherry’s cocktail party phenomenon, listeners are conscious of the presence of the unshadowed message and of whether there is an abrupt change of pitch (as in a change of voice from a man’s to a woman’s, or the introduction of a whistle). These global physical characteristics of the unshadowed message can be determined preattentively. Listeners are not conscious, however, of the contents or the language of the unshadowed message, of whether the language changed during the message, or even of whether speech or nonsense sounds were presented, unless a change of pitch occurred. Many variations of this experiment have been performed, and all have produced the same results: consciousness of the unshadowed material is limited to information that could be detected preattentively. There is no consciousness of the meaning of the unshadowed message, except that listeners sometimes are conscious of their own name if it appears, as a result of powerful schemata for something as important as one’s own name. The results are exactly what would be expected from what has been shown to be true of attention thus far and from the original description of the cocktail party problem.

Emergence of Attention Theories

The first complete theory of attention was not proposed until 1958, when Broadbent introduced his concept of attention as a filter that admitted only certain information, selected on the basis of sensory characteristics, into the limited-capacity system. This marked the continuation of interest in attention by researchers in England, beginning with Cherry in 1953. In 1963, J. Anthony and Diana Deutsch proposed that all incoming information is analyzed to the level of meaning.

Many of the fundamental issues in attention have been recast somewhat in an information-processing mode, beginning in the late 1960s. For example, attention is described in terms of “selection,” “resources,” “features,” “input,” and so on. Whereas the emphasis had previously been on hearing, visual attention began to receive more emphasis. Many of the findings were like those on hearing, although factors such as color and brightness were considered.

Attention remains central to the study of consciousness and cognitive psychology. As Michael Posner noted in 1975, “Attention is not a single concept, but the name of a complex field of study.” Accordingly, questions about early versus late selection, automatic processing, and other issues in the control of attention have not yet been fully answered.

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