摘要：@@ Continued from Issue 61rnTextual EnhancementrnThere are a number of studies that have investigated the effects of textual enhancement on drawing the learner's attention to grammar, and the method has been described as the least explicit and the least intrusive method of focus on form (Doughty & Varela, 1998). It involves highlighting certain features of input that might go unnoticed under normal circumstances by typographically manipulating them through boldfacing, italicizing, underlining, or capitalizing. The assumption is that such manipulations enhance the perceptual saliency of the target structures, and this, hence, increases their chance of being noticed. A related technique is the provision of numerous instances of target linguistic forms in the input, called an input flood (Trahey & While, 1993). Again,the assumption is that frequent exposure to target items enhances their saliency and hence results in noticing the forms (Schmidt, 1990; Sharwood Smith, 1993). Whereas studies by Doughty (1991) and Fotos (1994) reported positive results in terms of awareness of target structures and proficiency gains resulting from textually enhanced structures, a study by White (1998) did not show that learners who received textually enhanced input differed significantly in their ability to use the target structure compared with those who did not.White concluded that the method of enhancement may not have been sufficiently explicit to draw the learners' attention to the type of linguistic features that involved L1-L2 contrasts. Similarly, Leow (2001) investigated the effects of textual enhancement on learning Spanish formal imperatives and found no advantage for enhanced text over unenhanced text.Finally, Izumi (2001) compared two types of focus on form strategies, output and visual input enhancement, on the learning of English relativization by adult ESL learners, finding that those who produced output developed more than those merely received input. However, the visual enhancement did not result in gains in accuracy using the target form.
