In addition to aiding in overcoming memory limitations and facilitating learning through various semantic "chunking" and organizing devices, the properties of light are extensively used to aid attention during information processing. Bold print may be used to call attention to certain information and color can guide information processing, as when a red line is used in an electronics diagram to permit a particular circuit to be traced in an array of circuits printed in black.

Learning strategies instruction may include pre-reading activities in which bold faced, italicized, or segregated (as by white space) words or phrases are first surveyed to activate prior knowledge about what is to be read in greater detail. This is done to increase comprehension and make learning more effective.

Study techniques such as highlighting or underlining with colored pens use the electromagnetic spectrum as tools for focussing attention and reducing the amount of information that must be processed in a second reading (itself a learning strategy made possible by the permanence feature of graphics technology).

As with all technology, the power of graphics technology arises from its use to develop tools for amplifying and extending human capabilities.4 However, unlike hammers, sewing machines, automobiles, and other technologies that extend human strength, dexterity, or locomotion abilities, graphic technologies gain their power from their application to the extension of human cognition and the ability to manipulate information in symbolic form.

In particular, the merging of graphics technology with spoken language, itself a form of human technology for communicating with symbols, produces the power behind, and the awe and appreciation of, literacy.

The Graphic Representation of Spoken Language. The capstone achievement in graphics technology was the development of the alphabet, a relatively simple technology by means of which a few graphic marks can represent enough aspects of the oral language that the marks permit a reader to reconstruct a language-based message from the graphic display .6 The importance of this is that it permits graphic language to draw on the power of oral language for representing and communicating knowledge, while bringing the power of the three features of graphics technology to bear on the development of new knowledge and tools for thinking and problem solving.

Knowledge, The Human Cognitive System, and Reading. Just as the oral language is used to represent knowledge (ideas; thoughts) in the acoustic medium, the alphabetic writing system is used to represent knowledge in the graphic medium. In both these cases, knowledge is both the beginning and end product of communication.

Because knowledge can be represented in different modes, as in drawings, speech, written language, dance, and so forth, it is useful to consider the person as possessing a knowledge base that can be operated on by different sets of procedural rules (themselves a part of the knowledge base) to represent the knowledge. In a very simplified model of a human cognitive system (HCS) the system has a long term memory in which the knowledge base is stored, a short term or working memory that is actively involved in processing information, and a sensory/perceptual system for picking-up and placing information in the environment.

When the person is listening to speech, the HCS is picking up information in the acoustic medium and simultaneously picking up information from the internal knowledge base and merging the two to comprehend the message. Similarly, in reading, the person picks-up information from an external store of knowledge (a book; sign; list; table; etc.) and merges it with knowledge picked-up simultaneously from the internal knowledge base.