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Expert-Novice Differences and Adaptive Multimedia 209 Copyright 2006, Idea Group Inc. Copying or distributing in print or electronic forms without written permission of Idea Group Inc. is prohibited. in long-term memory highly automated due to extensive practice. To emphasize the decisive role of long-term memory in expert performance, Ericsson and Kintsch (1995) proposed the theory of long-term working memory (LTWM). According to this theory, long-term memory structures associated with components of working memory create a LTWM structure that is capable of holding virtually unlimited amounts of information. Recent studies of the expertise reversal effect (see Kalyuga, 2005; Kalyuga, Ayres, Chandler, & Sweller, 2003, for an overview) have demonstrated that information or a learning procedure that is beneficial for novice learners may become redundant for more knowledgeable learners. The expertise reversal effect can be related to research on aptitude-treatment interactions (e.g., Cronbach & Snow, 1977; Shute, 1992) that occur when different instructional treatments result in different learning outcomes depending on student aptitudes (knowledge, skills, learning styles, personality characteristics, etc.). In the expertise reversal effect, prior knowledge is the aptitude of interest. The effect can be explained by assuming that for more knowledgeable learners, the redundant material or instructional guidance overloads working memory relative to information without redundancy because resources are required for cross-referencing presented and previously-learned information. Accordingly, cognitive efficiency of multimedia presentations is relative to levels of user proficiency in a domain. Using appropriate procedures and removing redundant information at each level of user expertise, thus minimizing interfering cognitive load, is necessary for optimizing cognitive resources when designing multimedia presentations. For example, in a set of studies conducted with technical apprentices of a manufacturing company (Kalyuga, Chandler, & Sweller, 2000), detailed auditory explanations of procedures for using specific types of diagrammatic representations (cutting speed nomograms) that were presented simultaneously with animated diagrams were cognitively optimal multimedia instructional formats for novice trainees. However, at higher levels of expertise achieved after a series of intensive training sessions, when cognitive activities of the same users were based on well-learned schematic procedures, presenting a slightly different type of nomograms with detailed auditory explanations was suboptimal. Explanations designed to support construction of schematic knowledge structures that had already been acquired by trainees were redundant and inefficient. According to cognitive theories of multimedia learning (Mayer, 2001, 2005; Sweller, 1999), when text and pictures are not synchronized in space (located separately) or time (presented after or before each other), the integration process may increase cognitive load due to cross-referencing different representations. Physically integrating verbal and pictorial representations may eliminate this split-attention effect (Mayer & Gallini, 1990; Sweller, Chandler, Tierney, & Cooper, 1990). Therefore, a cognitively-optimal design of multimedia presentations for novice users usually requires eliminating situations when attention is split between multiple complementing information representations (e.g., on-screen text and diagrams) by embedding sections of textual explanations directly into the diagram in close proximity to relevant components of the diagram. Alternatively, dual-modality formats should be used with segments of narrated text presented simultaneously with the diagram (or relevant animation frames). Also, providing detailed instructional guidance by using plenty of fully worked-out examples at the initial stages of learning is required for novice learners (Sweller, et al., 1998). On the other

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