Factors affecting the comprehension of global and local main idea.(Report)

This study investigated factors that would affect a reader's understanding of the main idea at the global level and explicit and implicit main ideas at the local level. Fifty-seven first-year university students taking a college reading course took a comprehension test on an expository text. Statistical analyses revealed that text structure had a moderate effect on the reader's understanding of the global main idea; only a weak correlation existed between comprehension of the global main idea and local main ideas, particularly the explicit main idea. Analysis of the local main idea's textual features suggested that identification of the explicit main idea was affected by the degree of explicitness, which was measured in terms of sentence structure, position in the paragraph, and the number of points in the sentence. Analysis of textual features associated with implicit main ideas indicated the complex role of example in illustrating the main idea. The study offers some practical implications for college reading curriculum and instruction as well as textbook writing.

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It is generally agreed by researchers and theorists that the ability to identify and state the main idea is central to meaning construction (Broek, Lynch, Naslund, Ievers-Landis, & Verduin, 2003; Graesser, Pomeroy, & Craig, 2002; Pressley, 1998; Stevens, 1988; Williams, 1988). In view of the critical role of the main idea, it is hardly surprising that learning to identify the main idea has long been central to the elementary school reading curriculum and beyond (Graves, 1986; Jitendra, Cole, Hoppes, & Wilson, 1998). Moreover, "getting the main idea" has been regarded as a litmus test of successful reading comprehension and, therefore, taught as a major reading strategy to bridge the gap between less able readers and more able readers (Fielding & Pearson, 1994). In other words, the ability to identify the main idea delineated between strong and weak readers.

Over the years, the reading community has continued the inquiry into main idea comprehension, directing its attention to the reader's confidence and prior knowledge (Afflerbach, 1990; Davey & Miller, 1990; Pressley, Ghatala, Pirie, & Woloshyn, 1990); the number of examples and placement of the topic sentence in the text (Beishuizen, Asscher, Prinsen, & Elshout-Mohr, 2003; Day & Zajakowski, 1991; Harp & Mayer, 1998); and strategy instruction (Jitendra, Hoppes, & Xin, 2000). Given the extreme importance of reading comprehension in learning and the central role of the main idea in reading comprehension, it is only natural to predict that research into main idea comprehension will continue until national reading levels improve and college students are capable of understanding their textbooks at the level expected by their professors. In short, there is still much to be learned and understood about the main idea from the perspective of reading researchers, educators, and readers.

This study differentiated between main ideas on two levels: the global main idea at the text or discourse level, and the local main idea at the paragraph level. Furthermore, the local main idea was broken down into two categories: explicit and implicit. Due to the difference in text structure between narration and exposition, this study focused on expository text and its text structure. It examined to what extent the global main idea was related to the local main idea and text structure. It also took a closer look at the local main ideas in terms of their explicitness or implicitness, as determined by textual features. Specifically, three research questions guided this study:

1. Of the local main idea and text structure, which would better predict and account for students' ability to identify the global main idea?

2. What textual features would make the explicit main idea more explicit?