ILLUSTRATIONS ARE FOUND IN INSTRUCTIONAL MATERIALS FOR A WIDE VARIETY OF SUBJECTS. Pictures, charts, graphs, and diagrams are all examples of illustrations employed in educational fields. When properly utilized, static and dynamic illustrations can enhance instruction and facilitate learning. As potential benefits can be high, it is important for designers of instructional messages to think carefully about how and when they will use visual illustrations in instructional materials. This article presents some guidelines for the instructional use of still and moving images, indicating situations for which research has shown them to be most effective.

Illustrations in instructional materials serve different types of functional roles. Depending on the context, images can be used to: 

•Attract learners' attention 

•Help learners recall information (for example, pictures representing content from a text provide memory cues for readers.) 

•Visually explain information that would be difficult to convey using only verbal or written terms (Duchastel & Waller, 1979). For instance, data displayed in bar graphs is easier to follow and understand then the same data in text-only form.

Research indicates that static (still) visual illustrations can facilitate knowledge acquisition when they are presented with texts. However, the positive effects of illustrations vary, and are not found in all learning situations. The following broad guidelines (Anglin, Towers, & Levie, 1996) may help designers of instructional messages:

• Consider using illustrated visuals that contain text-redundant information, as these can facilitate learning in various subjects. 
• Illustration variables (cueing) such as size, page position, style, color, and degree of realism may direct attention, but might not significantly increase learning. 
• There is a curvilinear relationship between the degree of realism in illustrations and subsequent learning. Therefore, producing costly, highly-realistic illustrations might not be worthwhile in some situations. 
• Illustrations which are not text-redundant neither help nor hinder learning. 
  

Dynamic (moving) images, such as animated sequences, are typically more difficult to produce than still images. Though they attract more attention than still images, their high costs suggest that their use be limited to situations in which at least one of the following criteria apply:

• Motion and movement are important attributes of the instructional content being presented. For example, moving images would be well-suited for lessons on velocity.
• Dynamic images can be used to facilitate explanations and learning of complex procedural tasks or processes. For instance, this dynamic visual helps illustrate the process by which atoms form molecules.
  

If either of the above factors hold, then using dynamic images for instruction may be justifiable and beneficial. However, research has not yet demonstrated advantages for using dynamic images in other instructional situations. In cases where animations are incidental to learning (such as in many computer-based instructional programs), their relatively high production costs make it difficult to recommend them. Production of dynamic images can only be recommended when their unique qualities make moving images the most effective means of teaching a subject.

Joseph Sherman