In describing graphics, most of us use terms such as line art or photograph that refer to their surface features. But for learning purposes, the functional characteristics that affect how the illustration communicates information or how it facilitates psychological learning processes are more important than its surface features. Therefore we present three different views of visuals based on their (1) surface features that focus on what they look like and how they are created, (2) communication functions that focus on how they convey information, and (3) psychological functions that focus on how they facilitate human learning processes. Table 1.2 summarizes these three views.

Psychological Functions of Visuals.

In addition to communicating effectively, your visuals also must support critical psychological learning processes. Visuals that disrupt these processes have been shown to depress learning. For example, Harp and Mayer (1998) found that adding visuals and text that were topically related to the lesson but extraneous to the lesson goal depressed learning. They created two versions of a lesson that taught the process of lightning formation. The basic lesson version used words and relevant visuals to depict the process. The enhanced lesson version added short vignettes with visuals such as a video of lightning striking trees, an ambulance arriving near the trees, and a lightning victim being carried in a stretcher to the ambulance. At the same time, the narrator said: "Approximately 10,000 Americans are injured by lightning every year...." (p. 415). Learning was about 30 percent better for students using the basic lesson version lacking the graphic enhancements. The enhancements actually depressed learning because they interfered with the psychological processes involved in learning how lightning forms.

Figure 1.2. Three Representations of a Simple Procedure.

Table 1.3. Communication Functions of Graphics.

Function	A Graphic Used to	Examples
Decorative	Add aesthetic appeal or humor	Art on the cover of a book Visual of a general in a military lesson on ammunition
Representational	Depict an object in a realistic fashion	A screen capture of a software screen A photograph of equipment
Mnemonic	Provide retrieval cues for factual information	A picture of a stamped letter in a shopping cart to recall the meaning of the Spanish word, Carta (letter)
Organizational	Show qualitative relationships among content	A two-dimensional course map A concept map
Relational	Show quantitative relationships among two or more variables	A line graph A pie chart
Transformational	Show changes in objects over time or space	An animation of the weather cycle A video showing how to operate equipment
Interpretive	Illustrate a theory, principle, or cause-and-effect relationships	A schematic diagram of equipment An animation of molecular movement

To promote the design and planning of graphics that work with rather than against human learning processes, we describe a third way to catalog illustrations based on learning processes. This classification system summarized in Table 1.4 organizes graphics according to how they support the six psychological events of learning that are overviewed later in this chapter and described in greater detail in Chapter Three.

Table 1.4. Psychological Functions of Graphics.

Instructional Event	Definition	Example
Support Attention	Graphics and graphic design that draw attention to important elements in an instructional display and that minimize divided attention	An arrow to point out the relevant part of a computer screen Placement of graphic close to text that describes it
Activate or Build Prior Knowledge	Graphics that engage existing mental models or provide high-level content overview to support acquisition of new information	Visual analogy between new content and familiar knowledge Graphic overview of new content
Minimize Cognitive Load	Graphics and graphic design that minimize extraneous mental work imposed on working memory during learning	Line art versus photograph Relevant graphic versus decorative graphic
Build Mental Models	Graphics that help learners construct new memories in long-term memory that support deeper understanding of content	A schematic diagram to illustrate how equipment works A visual simulation of how genes are transmitted from parents to offspring
Support Transfer of Learning	Graphics that incorporate key features of the work environment; graphics that promote deeper understanding	Use of software screen simulation that looks and acts like actual software Use of a visual simulation to build a cause-and-effect mental model
Support Motivation	Graphics that make material interesting and at the same time do not depress learning	A graphic that makes the relevance of the skills to the job obvious An organizing visual that clarifies the structure of the material

The goal of the training is a second factor that influences the value of a given graphic. Certain kinds of visuals support memory for content. Other kinds of visuals help learners see the relationships among information in a lesson and in turn help learners build mental models that are the basis for higherlevel thinking and problem solving. Therefore, the value of a particular visual depends on your instructional goal.

In addition, visuals should be selected based on the type of content included in your learning materials. In Section Three of this book, we describe the selection of visuals to support five content types that make up much of the information included in training for work settings.

The same visual treatment may be more helpful to some learners than to others, depending on their prior knowledge and on their spatial abilities. For example, Gyselinck and her colleagues (2002) compared the learning of high and low spatial ability students from physics lessons that distributed explanatory text with and without illustrations over several screens. To learn the lesson concepts, students needed to integrate the information spread among the screens.

The researchers found that adding relevant illustrations to the text significantly increased learning of high but not low spatial ability students. Figure 1.3 summarizes part of their results. They conclude that "altogether, these results suggest that a high spatial capacity could help subjects integrate pictorial and verbal information efficiently" (p. 675). In Chapter Ten we summarize what is known about individual differences in the processing of and learning from graphics.

In summary, we see that several factors interact to determine the influence of any given visual on learning. These include the surface and functional features of the graphics, the intended learning outcome (such as memory for content or application of content), as well as the type of content taught and the learners' profile, including their prior knowledge of the lesson content and their spatial abilities. Because it is the interplay of these various elements that determines the instructional effectiveness of a graphic, there are no simple rules for deciding on the best visual for your training materials. Throughout the book we provide guidelines that will help you plan or select visuals that are likely to improve learning. You will need to adapt these guidelines to your own unique mix of learners, learning goals, and lesson content.

Figure 1.3. Mean Percentage Correct Responses of High and Low Spatial Learners Studying Lessons With and Without Graphics.

Decorative graphics like the one shown in the Introduction (Figure I.3) are added to instruction for aesthetic, humorous, or motivational purposes. Although they may be related topically to the content of the lesson, they are largely extraneous to its goals. Often, decorative graphics are included to add visual appeal or interest to a lesson.

Self-paced multimedia lessons, in particular, are subject to high learner attrition, so decorative eye candy is often added to spice up the materials. However, excessive use of decorative graphics risks interfering with essential cognitive learning processes needed to promote learning. Therefore, we discourage their use.

Representational visuals portray the appearance of lesson content. The goal is to illustrate what the content looks like in a realistic manner. Some examples include illustrations of a keyboard, a new DVD player, or a software application screen. These kinds of visuals often have a high degree of fidelity as in photographs or screen captures. They can also omit extraneous detail as in a line drawing. The key to representational graphics is that they are intended to faithfully represent the "real" object.

Mnemonic visuals aid in the recall of lesson facts and concepts. For example, Figure 1.4 shows a visual mnemonic used to illustrate the concepts of three types of columns: Doric, Ionic, and Corinthian.

Mnemonic graphics capture the meaning of facts or concepts and link them visually to a different concept that provides a bridge to their meaning, a visual analogy. Thus, we see the visual representation of a "door" in the mnemonic visual that leads you to the name and look of a Doric column. Mnemonics have proved to be very powerful memory retrieval devices (Carney and Levin, 2002). One limitation to mnemonics is their cultural or linguistic specificity. This specificity makes many mnemonic treatments difficult to disseminate to a global audience.

Figure 1.4. A Visual Mnemonic.

Organizational visuals illustrate qualitative relationships among lesson content. They are typically represented in trees, organizational charts, or in knowledge maps made up of nodes and links. Figure 1.5 shows an organizational graphic used to illustrate the relationship among major functions of a new software system.

Another common type of organizational visual is representation of lesson structure in a two-dimensional menu that communicates not only the topics but the relationship of topics to one another. Robinson and Molina (2002) report that some organizational visuals actually improve learning of conceptual relations better than do outlines that include the same information but lack the two-dimensional spatial representations.

Figure 1.5. An Organizational Graphic from a Software Lesson.

Relational visuals are used to communicate quantitative relationships among two or more variables and include charts and diagrams such as pie charts, line graphs, and bar charts. Figure 1.3 is a typical example. The use of relational graphics has grown from 900 billion in 1983 to 2.2 trillion in 1994 (Jones and Careras, 1994). However, only recently has controlled research focused on the kinds of graphs and charts that are most effective for specific purposes.

Transformational visuals communicate movement and change over time or over space. The surface features of transformational graphics can include animations, video, or line drawings with movement indicators. The visuals shown in Figure 1.2 are all examples of transformational visuals with different surface features.

Interpretive graphics help learners build mental models of events or processes that are invisible, abstract, or both. Figure 1.6 shows an interpretive visual in the form of a schematic diagram illustrating the functionality of a mechanical control panel. Kieras and Bovair (1984) showed that a lesson using this schematic to teach how equipment worked resulted in faster and more accurate job performance compared with lessons that taught only the procedures. The schematic helped learners build a mental model of how the equipment functioned. This mental model then supported more efficient use of the equipment and better troubleshooting.

Throughout the book we will summarize research that supports the use of these functional categories of visuals for specific instructional purposes. However, we anticipate that over time, additional studies will lead to updated guidelines. We offer this taxonomy as a starting point to help you plan graphics based on how they communicate your lesson content.

Figure 1.6. An Interpretive Graphic.

Learning is based on a transformation of new information from the environment into long-term memory as summarized in Figure 1.7. Two central memories are involved in this process: working memory and long-term memory. If attention is directed toward new incoming information, the information is stored in a visual and auditory storage area in working memory. Working memory is the center of human thought and active processing. Although it's a powerful processor, its storage capacity for information is quite limited. You may be familiar with the expression 7 plus or minus 2. This expression refers to the limits of working memory. Learning takes place when new content stored in the visual and in the phonetic components of working memory are integrated. First, the visual and phonetic information must be organized to form a cohesive idea. Then this idea must be integrated with activated prior knowledge from long-term memory. The outcome is an updated mental model stored in long-term memory.

Figure 1.7. Human Psychological Learning Process Overview.

Good instructional methods promote the processes that mediate the transformation of environmental information into new knowledge and skills in long-term memory. In Chapter Three we describe these events in greater detail.

First we emphasize selection and design of graphics based on their communication and psychological functions—not as commonly done, solely on their surface features. To guide you toward the communication and psychological functions of graphics, we will refer to categories from all three views of graphics summarized in Table 1.2. These taxonomies will provide you with an expanded way to think about and invest resources in graphics that will provide the most cost-effective outcomes for your instructional goals. We recommend that you make a copy of the tables in this chapter from our CD-ROM to use as a convenient memory aid as you read the book.

Second, we draw our recommendations from research evidence. We believe that the training and human performance field is moving toward a professional practice in which decisions will be based on scientific evidence as well as on pragmatic, technical, and political factors. Throughout the book we summarize what recent research tells us about how best to use visuals to support learning processes and communicate information needed to teach lesson content.

Most of the research we include is recent and drawn from experimental studies conducted with adult learners. In an experimental study, a large group is randomly assigned to a control condition and a treatment condition. For example, twenty-five individuals are randomly assigned to read a lesson consisting of just text (the control group) and another twenty-five are assigned to read the same lesson with graphics added (the treatment group). The random assignment of a large number of individuals to the control and experimental groups ensures that individual differences such as specific interests or abilities are evenly distributed between control and treatment groups and thus are not a factor in the results. After completing the lesson assignment, the subjects are tested. For the most part we have reported transfer test results rather than memory test results. That's because workers in organizations must be able to apply information—not just memorize it—and therefore application tests are more relevant to the instructional goals of organizations.

Keep in mind that most of the research we report has been conducted with college-age subjects. Although research on the impact of visuals on children's learning does exist, for the most part, we have excluded it. Also most of the graphic treatments used in the research studies are quite simple—often just line drawings like the ones illustrated in Figure 1.2A. and B. Because research that showed that different surface features for example—animated versus static versions—did not affect learning outcomes, we feel confident in making generalizations about graphics based on the visuals used in these studies. Naturally we will need to update our guidelines in the future based on emerging research.

Third, we recognize that decisions about graphics cannot be made independently of the entire instructional context. The selection or design of graphics is influenced by decisions regarding whether words will be included and in what format, for example, text or audio, and the delivery medium such as computers or books. Likewise pragmatic factors including project deadlines and budgets will influence visual treatments. In Section Four of this book we summarize a systematic process for design of graphics as part of an instructional landscape that must factor in these types of variables.

If you are responsible for planning or designing visuals for an instructional product—whether on your own or as part of a production team—you will be interested in Chapter Two. Here we overview a graphics design model that summarizes the various stages needed to plan and design visuals for instructional products. This model is expanded in Section Four. If you are not involved in the production of visuals, you may want to bypass Chapter Two and move to either Sections Two or Three that provide guidelines for selection of visuals based on their psychological functionality (Section Two) and on the content included in the lesson (Section Three).