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Acquisition Order (acquisition + order)
Selected AbstractsIs the Acquisition Order of Grammatical Morphemes Impervious to L1 Knowledge?LANGUAGE LEARNING, Issue 4 2009Articles, Evidence From the Acquisition of Plural - s, Possessive 's In SLA, it has been often assumed that the effect of the first language (L1) is not very strong in the acquisition of grammatical morphemes (e.g., Ellis, 1994; Mitchell & Myles, 2004). However, such an assumption has not been systematically examined in the literature. This article reviews the morpheme studies conducted with native speakers of Japanese, Korean, Chinese, and Spanish to test the effect of the L1 in the acquisition of grammatical morphemes. The review reveals that although Spanish L1 learners' acquisition order generally conforms to the "so-called" natural order (Krashen, 1977), native speakers of Japanese, Korean, and Chinese mostly acquire plural ,s,and articles later than, and possessive,'s,earlier than, is predicted by the natural order. This indicates that learners can acquire a grammatical morpheme later or earlier than predicted by the natural order, depending on the presence or absence of the equivalent category in their L1. This suggests that L1 transfer is much stronger than is portrayed in many SLA textbooks and that the role of L1 in morpheme acquisition must be reconsidered. [source] Explaining the "Natural Order of L2 Morpheme Acquisition" in English: A Meta-analysis of Multiple DeterminantsLANGUAGE LEARNING, Issue S1 2005Jennifer M. Goldschneider This meta-analysis pools data from 25 years of research on the order of acquisition of English grammatical morphemes by students of English as a second language (ESL). Some researchers have posited a "natural" order of acquisition common to all ESL learners, but no single cause has been shown for this phenomenon. Our study investigated whether a combination of 5 determinants (perceptual salience, semantic complexity, morphophonological regularity, syntactic category, and frequency) accounts for the variance in acquisition order. Oral production data from 12 studies, together involving 924 participants, were pooled to obtain weighted accuracy scores for each of 6 grammatical functors. Results of a multiple-regression analysis showed that a large portion of the total variance in acquisition order was explained by the combination of the 5 determinants. Several of these determinants, it was argued, can be seen as part of a broad conceptualization of salience. Since the article was originally published, a number of meta-analyses have appeared in the applied linguistics literature (e.g., Masgoret & Gardner, 2003; Norris & Ortega, 2000; Ortega, 2003), and a book on meta-analysis in applied linguistics research is forthcoming (Norris & Ortega, in press). Meanwhile, research on the acquisition of Hebrew as a second language has begun to provide cross-linguistic evidence for how different aspects of salience contribute to ease or difficulty of second language acquisition (DeKeyser, Alfi-Shabtay, Ravid, & Shi, 2005) and how salience interacts with age of learning (DeKeyser, Ravid, & Alfi-Shabtay, 2005). [source] Explaining the "Natural Order of L2 Morpheme Acquisition" in English: A Meta-analysis of Multiple DeterminantsLANGUAGE LEARNING, Issue 1 2001Jennifer M. Goldschneider Some researchers have posited a &;ldquo;natural&;rdquo; order of acquisition of English grammatical morphemes common to all learners of English as a second language, but no single cause has been shown for this phenomenon. This meta-analysis investigated whether a combination of five determinants (perceptual salience, semantic complexity, morphophonological regularity, syntactic category, and frequency) accounts for a large part of the total variance found in acquisition order. Oral production data from 12 studies over almost 25 years, together involving 924 subjects, were pooled. Multiple regression analysis showed that a very large portion of the total variance in acquisition order is explained by the combination of the five determinants. We suggest research on other potential contributing factors and discuss the need for similar research in other languages. [source] Self-navigated motion correction using moments of spatial projections in radial MRIMAGNETIC RESONANCE IN MEDICINE, Issue 2 2004Edward Brian Welch Abstract Interest in radial MRI (also known as projection reconstruction (PR) MRI) has increased recently for uses such as fast scanning and undersampled acquisitions. Additionally, PR acquisitions offer intrinsic advantages over standard two-dimensional Fourier transform (2DFT) imaging with respect to motion of the imaged object. It is well known that aligning each spatial domain projection's center of mass (calculated using the 0th and 1st moments) to the center of the field of view (FOV) corrects shifts caused by in-plane translation. In this work, a previously unrealized ability to determine the in-plane rotational motion of an imaged object using the 2nd moments of the spatial domain projections in conjunction with a specific projection angle acquisition time order is reported. We performed the correction using only the PR data itself acquired with the newly proposed projection angle acquisition time order. With the proposed view angle acquisition order, the acquisition is "self-navigating" with respect to both in-plane translation and rotation. We reconstructed the images using the aligned projections and detected acquisition angles to significantly reduce image artifacts due to such motion. The theory of the correction technique is described, and its effectiveness is demonstrated in phantom and in vivo experiments. Magn Reson Med 52:337,345, 2004. © 2004 Wiley-Liss, Inc. [source] Optimal acquisition orders of diffusion-weighted MRI measurementsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2007Philip A. Cook PhD Abstract Purpose To propose a new method to optimize the ordering of gradient directions in diffusion-weighted MRI so that partial scans have the best spherical coverage. Materials and Methods Diffusion-weighted MRI often uses a spherical sampling scheme, which acquires images sequentially with diffusion-weighting gradients in unique directions distributed isotropically on the hemisphere. If not all of the measurements can be completed, the quality of diffusion tensors fitted to the partial scan is sensitive to the order of the gradient directions in the scanner protocol. If the directions are in a random order, then a partial scan may cover some parts of the hemisphere densely but other parts sparsely and thus provide poor spherical coverage. We compare the results of ordering with previously published methods for optimizing the acquisition in simulation. Results Results show that all methods produce similar results and all improve the accuracy of the estimated diffusion tensors significantly over unordered acquisitions. Conclusion The new ordering method improves the spherical coverage of partial scans and has the advantage of maintaining the optimal coverage of the complete scan. J. Magn. Reson. Imaging 2007;25:1051,1058. © 2007 Wiley-Liss, Inc. [source] | ||||||||||