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Background: Previous research in the field of content and language integrated learning (CLIL) has not yet comprehensively investigated the interaction between learners' expertise and the instructional effectiveness. Aims: Taking cognitive load theory as the theoretical framework, a study was conducted to investigate the expertise reversal effect on learning English and mathematics simultaneously: whether an integrated approach (i.e. learning both English and mathematics simultaneously) could facilitate the acquisition of mathematic skills and English linguistic skills as a foreign language more effectively and efficiently than a separated learning approach (i.e. learning Mathematics and English separately). Materials: The materials for the integrated learning approach were in English‐only, and the materials for the separated learning approach were in English‐and‐Chinese. Both sets of materials were given as reading content for teaching mathematic skills and English as a foreign language. Methods: The study adopted a 2 (language expertise: low vs. high) × 2 (instruction: integrated vs. separated) between‐subject factorial design with instructional approaches and learners' expertise in English as independent variables, the learning performance in Mathematics and English with the cognitive load ratings as the dependent variables. Sixty‐five Year‐10 students with lower expertise in English and 56 Year‐2 college students with higher expertise in English in China were recruited and allocated to two instructional conditions respectively. Results: An expertise reversal effect was confirmed: the English and mathematics integrated learning approach was more effective for higher expertise learners while the English and mathematics separated learning condition was more beneficial for lower expertise learners. [ABSTRACT FROM AUTHOR]

High school students have been reported to have difficulties solving complex algebraic problems. This study therefore investigated the effects of worked example instruction on students' learning outcomes in solving complex algebraic problems. The study was a quasi-experiment that involved a pre-test, an intervention, a post-test, and a delay test. The responses of 72 students (aged 14 to 15 years) were scored following the structure of the observed learning outcomes (SOLO) model and analysed using the Rasch model and regression analysis. The results indicated a significant effect of worked examples from the pre-test to the post-test; however, this effect was not completely retained at the delay test. Also, worked examples had a larger effect on the low-ability students than the highability students, but student gender neither influenced nor interacted with learning outcomes at the post-test and delay test. Lastly, the results revealed an interaction between the worked example effects and students' expertise level, with the highability students experiencing a full reversal of the worked example effect. These results are explained with respect to element interactivity and expertise reversal effects, and inform mathematics educators and teachers of the conditions of the worked example effect and the implications for classroom practices. [ABSTRACT FROM AUTHOR]

Several studies highlight the importance of the order of different instructional methods when designing learning environments. Correct but also erroneous worked examples are frequently used methods to foster students' learning performance, especially in problem-solving. However, so far no study examined how the order of these example types affects learning. While the expertise reversal effect would suggest presenting correct examples first, the productive failure approach hypothesizes the reversed order to be learning-facilitating. In addition, congruency of subsequent exemplified problems was tested as a moderator of the effect of order on learning. For example, with arithmetic tasks, congruent problems target exactly the same calculation while incongruent problems refer to different calculations. Following cascade theory, a model of cognitive skill acquisition, presenting correct examples first should be more effective when the subsequent exemplified problems are different. To test the (conflicting) hypotheses, 83 university students were assigned to one of the four conditions in a 2 (correct vs. erroneous example first) x 2 (same vs. different exemplified problems) between-subject design. Learners navigated through a slideshow on the topic of Vedic mathematics consisting of explicit instruction, worked examples differing in terms of the experimental condition, and transfer problems. Although no main or interaction effects were found regarding students' learning performance, mediational analysis offered support for the expertise reversal effect, as it indicated that there is a significant indirect effect of order via mental load on learning. Presenting correct examples first and erroneous examples second resulted in a lower mental load, which in turn was associated with better learning performance. In contrast, presenting erroneous examples first and correct examples second resulted in a more accurate self-assessment of learning performance. These findings offer first insights into the question of how the presentation order of different example types impacts learning and provide practical recommendations for the design of educational media. Results are discussed in light of the ongoing debate regarding the question if less guided instructional methods should precede or succeed more guided methods. [ABSTRACT FROM AUTHOR]

Several studies highlight the importance of the order of different instructional methods when designing learning environments. Correct but also erroneous worked examples are frequently used methods to foster students’ learning performance, especially in problem-solving. However, so far no study examined how the order of these example types affects learning. While the expertise reversal effect would suggest presenting correct examples first, the productive failure approach hypothesizes the reversed order to be learning-facilitating. In addition, congruency of subsequent exemplified problems was tested as a moderator of the effect of order on learning. For example, with arithmetic tasks, congruent problems target exactly the same calculation while incongruent problems refer to different calculations. Following cascade theory, a model of cognitive skill acquisition, presenting correct examples first should be more effective when the subsequent exemplified problems are different. To test the (conflicting) hypotheses, 83 university students were assigned to one of the four conditions in a 2 (correct vs. erroneous example first) × 2 (same vs. different exemplified problems) between-subject design. Learners navigated through a slideshow on the topic of Vedic mathematics consisting of explicit instruction, worked examples differing in terms of the experimental condition, and transfer problems. Although no main or interaction effects were found regarding students’ learning performance, mediational analysis offered support for the expertise reversal effect, as it indicated that there is a significant indirect effect of order via mental load on learning. Presenting correct examples first and erroneous examples second resulted in a lower mental load, which in turn was associated with better learning performance. In contrast, presenting erroneous examples first and correct examples second resulted in a more accurate self-assessment of learning performance. These findings offer first insights into the question of how the presentation order of different example types impacts learning and provide practical recommendations for the design of educational media. Results are discussed in light of the ongoing debate regarding the question if less guided instructional methods should precede or succeed more guided methods.

Purpose: Guided by cognitive load theory and cognitive theory of multimedia learning, the purpose of this study was to evaluate players' ability to integrate dynamic information presented under different conditions: a verbal condition, in which instructions were given orally; a visual condition, in which instructions were shown using arrow symbols; and a redundant condition, in which both visual and verbal instructions were presented simultaneously. Method: In a 2 × 3 design, we asked basketball players with varied levels of skill (less-skilled, skilled) to rate their invested mental effort and to perform a recall test after learning from either the verbal, visual or redundant condition. Results: Results demonstrated that the less-skilled players benefited more from the redundant condition, whereas the skilled participants benefited more from the visual condition. Conclusion: Recommendations for improving instructional design techniques aimed at the transmission of tactical instructions in team games are proposed. [ABSTRACT FROM AUTHOR]

The concept of productive failure posits that a problem-solving phase prior to explicit instruction is more effective than explicit instruction followed by problem-solving. This prediction was tested with Year 5 primary school students learning about light energy efficiency. Two, fully randomised, controlled experiments were conducted. In the first experiment (N = 64), explicit instruction followed by problem-solving was found to be superior to the reverse order for performance on problems similar to those used during instruction, with no difference on transfer problems. In the second experiment, where element interactivity was increased (N = 71), explicit instruction followed by problem-solving was found to be superior to the reverse order for performance on both similar and transfer problems. The contradictory predictions and results of a productive failure approach and cognitive load theory are discussed using the concept of element interactivity. Specifically, for learning where element interactivity is high, explicit instruction should precede problem-solving. [ABSTRACT FROM AUTHOR]

Based on cognitive load theory, this paper reports on two experiments investigating the variability effect that occurs when learners' exposure to highly variable tasks results in superior test performance. It was hypothesised that the effect was more likely to occur using high rather than low levels of guidance and testing more knowledgeable than less knowledgeable learners. Experiment 1, which tested 103 adults studying pre-university mathematics, showed no interaction between levels of variability (high vs. low) and levels of instructional guidance (worked examples vs. unguided problem solving). The significant main effect of variability indicated a variability effect regardless of levels of instructional guidance. Experiment 2, which tested another group of 56 adults enrolled in the same mathematics program, showed an interaction between levels of variability (high vs. low) and levels of learner expertise (novices vs. experts). More experienced learners learned more from high rather than low variability tasks demonstrating the variability effect, while less experienced learners learned more from low rather than high variability tasks demonstrating a reverse variability effect. It was suggested that more experienced learners had sufficient available working memory capacity to process high variability information while less experienced learners were overwhelmed by high variability and learned more using low variability information. Subjective ratings of difficulty supported the assumptions based on cognitive load theory. The major educational implication is that learners should initially be presented with low variability or easier tasks, and as they gain more experience in the task domain, variability or task difficulty should increase. [ABSTRACT FROM AUTHOR]

The expertise reversal effect occurs when instruction that is effective for novice learners is ineffective or even counterproductive for more expert learners. Four experiments designed to explore the expertise reversal effect in the field of teaching and learning foreign language listening skills were conducted. Three instructional formats (read-only, listen-only, and read-and-listen) were designed to teach native Chinese students English (experiments 1-3) or French (experiment 4) listening skills. Experiment 1 found a significant interaction with no effect for learners with lower levels of listening expertise but a significant effect for learners with higher levels of listening expertise favoring the read-only approach. The results of experiment 2 replicated the counterintuitive findings of experiment 1. Experiment 3 testing less knowledgeable students than experiments 1 and 2 indicated that the read-and-listen condition was more effective for novice learners. Experiment 4 testing beginner-level learners of French as a foreign language obtained results consistent with those of experiment 3 in that lower expertise learners gained greater benefits from the read-and-listen than the read-only or listen-only teaching approaches. It is concluded that the read-and-listen approach benefitted novice learners but more expert learners could benefit more from the read-only approach. [ABSTRACT FROM AUTHOR]

In the traditional framework of cognitive load theory, it is assumed that the acquisition of domain-specific knowledge structures (or schemas) is the only instructional goal, and therefore, the theory is applicable to any instructional task. Accordingly, the basic concepts of intrinsic (productive) and extraneous (unproductive) types of cognitive load were defined based on the relevance (or irrelevance) of the corresponding cognitive processes that impose the load to achieving this universal instructional goal, and the instructional methods advocated by this theory are aimed at enhancing the acquisition of domain-specific schemas. The paper suggests considering this goal within the whole variety of possible specific goals of different learner activities that could be involved in complex learning. This would result in narrowing down of boundaries of cognitive load theory and have implications for distinguishing types of cognitive load, sequencing different goals and instructional tasks, considering the role of learner expertise, and other aspects of complex learning. One of the consequences of this reconceptualization is abandoning the rigid explicit instruction versus minimal guidance dichotomy and replacing it with a more flexible approach based on differentiating specific goals of various learner activities in complex learning. In particular, it may allow reconciling seemingly contradictory results from studies of the effectiveness of worked examples in cognitive load theory (supporting the initial fully guided explicit instruction for novice learners) and studies within the frameworks of productive failure and invention learning that have reportedly demonstrated that minimally guided tasks provided prior to explicit instruction might benefit novice learners. [ABSTRACT FROM AUTHOR]

Element interactivity is a central concept of cognitive load theory that defines the complexity of a learning task. The reduction of task complexity through a temporary segmentation or isolation of interacting elements was investigated with 104 students randomly assigned to an interacting elements group, where participants were required to deal with complex accounting problems in their entirety, or an isolated elements group, where the task was broken down into constituent components. The results provide strong support for the expertise reversal effect with isolated elements beneficial for novices, while interacting elements were appropriate for more knowledgeable learners. Critically, these results only were obtained for high rather than low element interactivity materials. It was concluded that segmentation or element isolation should consider the expertise of the learner in conjunction with the complexity of the learning material. [ABSTRACT FROM AUTHOR]

The aim of this paper is to examine the effects of sequencing instructional materials and learners' prior knowledge on learning ESL (English as a second language) through an online learning course. 121 fifth-grade students from an elementary school in Korea participated in the study. Each participant was allocated to one cell of a 2 × 2 between-subjects factorial design, with an instructional format (i.e. sequential or concurrent) as a first factor, and prior knowledge (i.e. high or low) as a second factor. Instructions of the words and grammar rules were allocated to each page for the sequential group, whereas integrated on a single page for the concurrent group. The result indicates that the sequential instruction of words followed by grammar explanations was more effective for the students with higher levels of prior knowledge than the concurrent presentation. The reverse was also found for the students with lower levels of prior knowledge in English. There are four possible explanations for the results. First, split-attention effect, temporal-contiguity effect, or transient information effect might occur. Second, worked-example effect might occur and over-ride the effect of sequencing. Third, intrinsic and extraneous cognitive load might intertwine each other. Last, the levels of element interactivity in two instructional formats might be different from each other. The implications for instructional designers and future research are discussed. [ABSTRACT FROM PUBLISHER]

Tailoring of instructional methods to learner levels of expertise may reduce extraneous cognitive load and improve learning. Contemporary technology-based learning environments have the potential to substantially enable learner-adapted instruction. This paper investigates the effects of adaptive instruction based on using the isolated-interactive elements effect that occurs when learners who are initially presented with elements of information in an isolated, non-interactive form (followed by a fully interactive form) outperform those who are presented with the same information only in a fully interactive form. Cognitive load theory explains the effect for novice learners by their potential cognitive overload when dealing with a fully interactive form of instruction from the beginning. However, according to the expertise reversal effect in cognitive load theory, the effect may reverse for relatively more knowledgeable learners. Experiment 1 found that more knowledgeable accounting students performed better with interactive rather than isolated presentations. For less knowledgeable learners, there was no statistically significant performance difference between the presentation formats. Thus, there was a significant interaction between the instructional procedures and levels of learner prior knowledge as an indicator of an expertise reversal effect. In one of the two conditions used in Experiment 2, information was adaptively presented in isolated form to less knowledgeable learners but in interactive form to more knowledgeable learners (based on the pre-tests of learner prior knowledge). In another (control) group, students were randomly allocated to isolated and interactive instructional formats irrespective of levels of their prior knowledge. As expected, the adaptive instruction group was superior to the non-adaptive group. The paper concludes with implications for the technology enabled design of learner-tailored instructional presentations. [ABSTRACT FROM AUTHOR]

Based on cognitive load theory, the effect of different levels of instructional detail and expertise in a simulation-based environment on learning about concepts of correlation was investigated. Separate versions of the learning environment were designed for the four experimental conditions which differed only with regard to the levels of written instructional detail. One hundred and forty Grade 10 (lower-expertise) and Grade 11 (higher-expertise) students participated in this experiment. In accord with the expertise reversal effect, the results supported the hypothesis that higher levels of instructional detail benefited learning for lower-expertise learners, whereas lower levels of detail facilitated learning for higher-expertise learners. It was concluded that the level of instructional guidance needed to match learners' levels of expertise. [ABSTRACT FROM AUTHOR]

The effect of instructional fading on student performance in online accounting instruction using completion problems was investigated in this study. Instructional fading, defined as the gradual decreasing of prompts or cues, was used as a strategy to create germane cognitive load. The Instructional Fading Tool for Accounting Practice, a web-based application developed by the researchers, provided the instructional fading and sequencing of the information. The researchers created control and treatment groups based on low and high prior knowledge of accounting. Results indicated that the treatment group had a higher percentage of an increase in performance than the control group. In addition, students within the low-prior knowledge treatment group outperformed students in the other treatment group and two control groups. These findings suggest that using instructional fading along with completion problems in accounting instruction had a positive effect on performance especially for students with low levels of prior knowledge. [ABSTRACT FROM AUTHOR]

The worked example effect indicates that examples providing full guidance on how to solve a problem result in better test performance than a problem-solving condition with no guidance. The generation effect occurs when learners generating responses demonstrate better test performance than learners in a presentation condition that provides an answer. This contradiction may be resolved by the suggestion that the worked example effect occurs for complex, high-element interactivity materials that impose a heavy working memory load whereas the generation effect is applicable for low-element interactivity materials. Two experiments tested this hypothesis in the area of geometry instruction using students with different levels of prior knowledge in geometry. The results of Experiment 1 indicated a worked example effect obtained for materials high in element interactivity and a generation effect for materials low in element interactivity. As levels of expertise increased in Experiment 2, thus reducing effective complexity, this interaction was replaced by a generation effect for all materials. These results suggest that when students need to learn low-element interactivity material, learning will be enhanced if they generate rather than study responses but if students need to learn high-element interactivity material, study may be preferable to generating responses. [ABSTRACT FROM AUTHOR]

Research has demonstrated that instruction that relies heavily on studying worked examples is more effective for less experienced learners compared to instruction emphasizing problem solving. However, the guidance associated with studying some worked examples may reduce the performance of more experienced learners. This study investigated categories of guidance using geometry worked examples. Three conditions were used. In the theorem and step guidance condition, students were provided with the solution steps required to reach the answer and the theorems used to justify the steps. In the step guidance condition, learners were only provided with the sequence of steps needed to reach the answer but not with the theorems explaining the steps. The problem-solving condition required learners to solve problems without any guidance. It was hypothesized that for students who had already learned the relevant theorems, the major task was to learn to recognize problem states and their associated solution moves. The step guidance condition should best facilitate such knowledge, compared to a problem-solving or a theorem and step guidance approach. For students who had not yet fully learned the theorems, the theorem and step guidance approach should be superior. Two geometry instruction experiments supported these hypotheses. Information concerning theorems should only be provided if students have yet to learn and automate theorem schemas. [ABSTRACT FROM PUBLISHER]

Providing prompts to induce focused processing of the central contents of instructional explanations is a promising instructional means to support novice learners in learning from instructional explanations. However, within research on the expertise reversal effect it has been shown that instructional means that are beneficial for novices can be detrimental for learners with more expertise if the instructional means provide guidance that overlaps with the internal guidance provided by the prior knowledge of learners with more expertise. Under such circumstances, prompts to induce focused processing might even be detrimental for learners with expertise whose prior knowledge already provides internal guidance to learn from explanations. On this basis, we aimed at experimentally varying expertise by developing prior knowledge. Specifically, we used a preparation intervention with contrasting cases to enhance learners' prior knowledge (expertise). Against this background, we tested 71 university students in a 2 × 2 factorial experimental design: (a) Factor of expertise. Working with contrasting cases to develop prior knowledge and expertise to provide internal guidance to learn from instructional explanations (with vs. without), (b) Factor of prompts. Prompts to induce focused processing of the explanations (with vs. without). The results showed that prompts to induce focused processing fostered conceptual knowledge for novice learners whereas prompts hindered the acquisition of conceptual knowledge for learners with expertise that was developed by working with contrasting cases beforehand. Moreover, measures of subjective cognitive load and learning processes suggest that the instructional guidance provided by prompts compensated for the low internal guidance of novice learners and overlapped with the internal guidance of learners with expertise. [ABSTRACT FROM AUTHOR]

The expertise reversal effect occurs when learner's expertise moderates design principles derived from cognitive load theory. Although this effect is supported by numerous empirical studies, indicating an overall large effect size, the effect was never tested by inducing expertise experimentally and using instructional explanations in a computer-based environment. The present experiment used an illustrated introductory text and a computer program about statistical data analyses with 93 students. Retention and transfer tests were employed as dependent measures. Each learner was randomly assigned to one condition of a 2 × 2 between subjects factorial design with the two factors expertise (novices vs. 'experts') and explanations (with vs. without). Expertise was induced by adding expository examples and illustrations to the introductory text to enhance text coherence and facilitate text comprehension. The expertise reversal effect was replicated for the dependent measure transfer, but not for retention. Results and implications for adaptive learning environments are discussed. [ABSTRACT FROM AUTHOR]

There have been several rather counterintuitive phenomena observed in different fields of research that compared the performance of experts and novices. For example, studies of medical expertise demonstrated that less experienced medical students may in some situations outperform seasoned medical practitioners on recall of specific cases. Studies of cognitive load aspects of complex skill acquisition in technical and academic domains demonstrated that more experienced technical trainees or students may learn less than expected from instructions that are very effective for novices. Finally, research in the execution of movements in sports showed that, while novice players performed well under skill-focused and accuracy conditions, such conditions inhibited performance of experts who benefitted from speed conditions. Apparently, in each of those phenomena, there is a mechanism that disrupted successful expert performance while, at the same time, enhanced performance of less experienced individuals. This paper presents a review of the expertise reversal effects that have been found in the different fields and identifies their specific underlying mechanisms and common origins. Knowledge of theoretical models and empirical findings in one of those fields could enrich research ideas and approaches in others. The implications of these ideas for research aimed at improving learning and instruction are discussed. [ABSTRACT FROM AUTHOR]

Two experiments using the science topics of Magnetism and Light were conducted with younger learners (Year 5) who had no prior knowledge of the topics, and older learners (Year 6) who had studied the topics previously. Half of the learners were presented the information in auditory form only while the other half were presented the auditory information simultaneously with a visual presentation. Results indicated that older students with prior knowledge of the topic learned more from the auditory only presentation. For these students, the addition of visual information was redundant and so they were disadvantaged by the use of an audio-visual presentation. However, for younger students with no prior knowledge of the topic, the difference between means reversed. Some of these students might require a visual presentation to make sense of the auditory explanation. These two sets of results were discussed in the context of the redundancy and the expertise reversal effect. [ABSTRACT FROM AUTHOR]

Although exploratory (inquiry-based, discovery, problem-based) learning environments have been effective for certain categories of learners and instructional situations, they could also be very cognitively demanding, especially for novice learners. Such forms of instruction may generate a heavy working memory load caused by intensive unguided search processes and result in reduced learning outcomes for these learners. This paper considers this situation as an example of the expertise reversal effect in cognitive load theory. It reviews relevant previous studies within this theoretical framework that compared exploratory and direct forms of instruction with learners at different levels of prior knowledge. Even though most of these studies have been conducted in well-defined areas, a of some recent studies in ill-defined domains is also provided. Implications for the design of learning environments with learner-tailored levels of instructional guidance are discussed in the concluding sections. [ABSTRACT FROM AUTHOR]

Abstract: Self-explanation prompts are considered to be an important form of scaffolding in the comprehension of complex multimedia materials. However, there is little theoretical understanding to date of self-explaining prompt formats tailored to different expertise levels of learners to help them fully exploit the advantages of dynamic multi-representational materials. To address this issue, this study designed two types of self-explaining prompts: the reasoning-based prompts asked the learners to reason the action run of the animation; the predicting-based prompts asked the learners to predict the upcoming action of the animation, and then asked for reasoning if they made a wrong prediction. Furthermore, multiple indicators including learning outcome, cognitive load demand, learning time, and learning efficiency were used to interpret the prompts’ effects on different expertise levels of learners. A total of 244 undergraduate students were randomly assigned to one of the three conditions: a control and two different self-explaining prompt conditions. The results indicate that the learning effects of self-explaining prompts depend on levels of learner expertise. Based on the results, this study makes recommendations for adaptive self-explaining prompt design. [Copyright &y& Elsevier]

This study investigated interactions between the isolated–interactive elements effect and levels of learner expertise with first year undergraduate university accounting students. The isolated–interactive elements effect occurs when learning is facilitated by initially presenting elements of information sequentially in an isolated form rather than in a fully interactive form. The expertise reversal effect occurs when the relevant advantage of one instructional technique over another reverses depending on the learner’s level of expertise. The results provided support for the predicted interaction with lower expertise students benefitting from the isolated elements instructional method, while students with more expertise learned more from the interacting elements format. [ABSTRACT FROM AUTHOR]

The reported study compared the instructional effectiveness of Modern English explanatory interpretations of Shakespearean play extracts integrated line by line into original Elizabethan English text, with a conventional unguided original text condition. Experiment 1 demonstrated that the explanatory notes group reported a lower cognitive load and performed better in a comprehension test than the control group when students had no prior knowledge of the text. In Experiment 2, a reverse effect occurred when the same material was presented to a group of Shakespearean experts. Experiment 3 replicated the results of Experiment 1 using a different Shakespearean play. The study demonstrated that the relative effectiveness of instructional conditions depended on learner levels of expertise. In accordance with the expertise reversal effect, the benefits of guided instruction reversed and became detrimental for learners with high prior knowledge levels. Retrospective verbal protocols indicated that the explanations were redundant for expert readers. [ABSTRACT FROM AUTHOR]

The effectiveness of mixed sensory mode presentation for beginning and experienced learners of Chinese characters as second language was investigated. Experiment 1 found that inexperienced 7th graders performed better on meaning recall in the mixed visual–audio mode than the visual mode presentation, but the superiority of these two formats was reversed for pronunciation. Experiment 2 revealed that 2 years later, the same learners performed better on both pronunciation and meaning in the mixed mode than the single mode presentation. The mixed format enhanced experienced learners'' learning and different modes of presentation should be taken into account for second language instruction. [Copyright &y& Elsevier]

The interactions between levels of learner prior knowledge and effectiveness of different instructional techniques and procedures have been intensively investigated within a cognitive load framework since mid-90s. This line of research has become known as the expertise reversal effect. Apart from their cognitive load theory-based prediction and explanation, patterns of empirical findings on the effect fit well those in studies of Aptitude Treatment Interactions (ATI) that were originally initiated in mid-60s. This paper reviews recent empirical findings associated with the expertise reversal effect, their interpretation within cognitive load theory, relations to ATI studies, implications for the design of learner-tailored instructional systems, and some recent experimental attempts of implementing these findings into realistic adaptive learning environments. [ABSTRACT FROM AUTHOR]