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2. BACKGROUND2.1. MEDIA TECHNOLOGIES OVERVIEWIntegration possibilities other than ES/MM are also the subject of this overview. Additional media technologies to be combined with ES include hypermedia (HM) and intellimedia (IM), the latter being a new concept of intelligent MM. Figure 1 depicts a hierarchy and evolution of MM, HM, and IM. The area allocated to each represents the approximate extent of general research interest indicated in the popular press, research reports, and journal articles. As will be briefly discussed later, IM is a form of the emerging technology of dynamic intelligent agents.
2.1.1. Multimedia An earlier study of MM (Lougheed and Ragusa, 1992) found that there is no universally accepted definition of MM. Fermoyle (1990) best explained the difficulties in defining MM with the following statement:
In addition to presentation systems, definitions included orientations toward hardware, software, integrated platforms, standards, and user interaction. In an article describing MM as the next frontier for business, Raskin (1990) states, "MM is not a product, nor even a technology. It's better seen as a platform -- a combination of hardware and software elements that together support a multisensory information environment" (p. 152). Adding to this confusion has been a lack of standards, which initially delayed the full adoption of MM devices, software, and platforms. The situation has improved with the acceptance of industry standards, which is important for product and media consistency and user acceptance. Presently, industry standards exist for multimedia PC (MPC) hardware and software products and have been developed by the Joint Photographic Experts Group (JPEG) for the compression and decompression of color still images. Standards also exist for full-motion video and audio, which were developed by the international Motion Picture Experts Group (MPEG). For the purpose of this chapter, MM is defined as the computer-facilitated integration of multiple information formats. As such, MM includes the use of two or more media forms, including (1) static media: text, data, graphics, still images; and (2) dynamic or time-varying media: animation, full-motion video, speech, and nonspeech audio (Ragusa, 1994). MM application systems strive to take advantage of human senses in order to facilitate communication and have become an important method of effective and expressive communications. Contrary to earlier forms of audio-visual technology, computer-based MM is a powerful technology that (1) allows the presentation of several media formats separately or simultaneously, and (2) has the functionality to provide nonlinear links within and between these media formats. This latter feature relates to the more advanced media technology form of HM. 2.1.2. Hypermedia HM has evolved from an earlier concept of hypertext (HT), which was first defined by Nelson in the early 1960s to mean "nonsequential writing, text that branches and allows choices to the reader, best read at an interactive screen" (Paske, 1990, p. 54). Like MM, HT can be defined from various perspectives. HT can be viewed in the context of a new model for textbook material. It can also be thought of as a computerized network of nodes or database objects and links to traverse between nodes to create and browse through complex networks of linked text and documents. More recently, HT has been widely used and accepted as a context linking methodology. However, because HT is primarily a single media form (text), it is not included further in the discussion in this chapter. Nelson later coined the term "hypermedia" to describe a higher bandwidth technology (and extension of HT) that combines various media forms (including text) in a unified information delivery system centered around the personal computer (Paske, 1990). Thus, HM represents the marriage of HT and MM. Included in this union are MM components such as two- and three-dimensional structured graphics, spreadsheets, video, sound, and animation. Frequently, the terms MM and HM are used interchangeably; however, HM is defined as a kind of MM information management and delivery system that links two or more media in an associative, nonlinear (nonserial) way, usually through a software application program. Currently, associative links are established by the system developer. More on this subject later. HM has also been characterized as (1) having several information structures where links are explicit; (2) being a form of MM (e.g., text, presentation, graphics, animations, voice); and (3) allowing information to be linked by association. The latter is consistent with the belief that HM should be able to reflect the ever-changing connections inherent in all information. A true HM system, however, (1) allows the connection of any piece of information (often called a node) with any other piece in a logical and coherent way; (2) allows users to attach annotations to any piece of information; and (3) provides maps and other navigational aids so users do not become lost in its information space. Ideally, users are able to interactively navigate through an MM information base by using their intuition, memory, and interests as a guide while always maintaining control. If carefully developed, HM makes information from multiple perspectives more meaningful. In effect, the user becomes the "interactor." In this way, HM can be used for a fast search of specific information because it has an open architecture and can be used with relative ease by non-programmers. This is distinctly different from ES "navigation" where the system provides control through user prompts and the rule inferencing process.
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