Media Research Center

About: Media Research Center is a based out in . It is known for research contribution in the topics: Collaborative learning & Educational technology. The organization has 491 authors who have published 950 publications receiving 28581 citations. The organization is also known as: MRC.

A neural disconnection hypothesis on impaired numerical processing.

Abstract: In recent years the number of fMRI studies aiming to pinpoint the neural substrates of number processing increased steadily (e.g., Dehaene et al., 2003; see Dehaene, 2009; Nieder and Dehaene, 2009 for reviews; see Arsalidou and Taylor, 2010 for a meta-analysis). Nevertheless, while considerable progress has been made, the neural correlates and cognitive mechanisms involved in the retrieval of arithmetic facts such as for multiplication (e.g., 2 × 3 = 6) or for addition (e.g., 2 + 3 = 5) fact knowledge is still a matter of debate. According to the currently most influential model of numerical cognition, the Triple Code Model by Dehaene and colleagues (Dehaene and Cohen, 1995, 1997; Dehaene et al., 2003) the retrieval of arithmetic fact knowledge is verbally mediated and subserved by a neural system relying on left-hemispheric perisylvian language areas and the angular gyrus. It is thus assumed that arithmetic facts are retrieved directly from long-term memory without the need of any magnitude manipulations. Instead, the verbally mediated representation format is claimed to trigger the retrieval of a word sequence from memory, which is associated with the AG (e.g., “two times three equals six”). Consistent with this prediction of the Triple Code Model, evidence from neuroimaging (e.g., Rickard et al., 2000; Delazer et al., 2003, 2005; Ischebeck et al., 2006, 2007; Grabner et al., 2009; Zamarian et al., 2009) as well as single-case studies with brain damaged patients (e.g., Hittmair-Delazer et al., 1994; Lee, 2000; Cohen et al., 2000) point to an involvement of the left angular gyrus (AG) in the retrieval of arithmetic facts. Compelling evidence for a functional involvement of the left AG comes from a training study by Delazer et al. (2003). In their study adults were trained on complex multiplication problems (e.g., 17 × 26 =) over 5 days. In a subsequent fMRI session, contrasts between trained and untrained problems revealed stronger activation in the left angular gyrus for the trained than the untrained set interpreted to indicate increased reliance on fact-retrieval to solve trained problems. In contrast, higher activation in frontal cortices and in the lPS for the untrained problems was suggested to reflect higher demands on executive functions and magnitude manipulations, respectively. In sum, these activation differences, in particular between the IPS and the angular gyrus for trained vs. untrained problems indicated a transition from quantity-based processing to direct fact retrieval (for similar results, see Ischebeck et al., 2007). However, there is also contradictory evidence in the literature. For instance, Van Harskamp et al. (2005) reported a patient with a severe multiplication fact-retrieval deficit, although his brain lesion did not involve the left AG. More particularly, a detailed review of single-case studies of patients, for whom neuroradiological images are available, revealed that also the lesion of patient BOO (Dehaene and Cohen, 1997), who presented with a selective impairment for multiplication, did not involve the AG, the supramarginal gyrus (SMG) or perisylvian language areas. This can be seen from the axial lesion drawings in Figure 3 (p. 226). Moreover, in patient ATH who also exhibited a severe impairment for rote multiplication (Cohen and Dehaene, 2000), the posterior part of the angular gyrus seemed spared. Additionally, Van Harskamp and Cipolotti (2001) reported a patient VP who presented with a selective impairment for simple multiplication problems and extended atrophy due to Alzheimer's disease, while the left angular gyrus was relatively spared. Finally, Zaunmueller et al. (2009) reported a patient with a severe multiplication fact-retrieval deficit although his brain lesion did neither involve the left AG or even left-hemispheric language areas. Thus, at a first glance these results do not seem to be in concordance with the notion that the left AG is critical for the retrieval of arithmetic (multiplication) facts nor that this structure in conjunction with temporal, frontal and subcortical areas is indeed critical for arithmetic (multiplication) fact knowledge as suggested by the Triple Code Model.

Visual inspection of 3-D surface and refractive-index profiles of microscopic lenses using a single-arm off-axis holographic interferometer.

Abstract: A single-arm off-axis holographic interferometer (SA-OHI) system for visual inspection of the three-dimensional (3-D) surfaces and refractive-index profiles of micrometer-scale optical lenses is proposed. In this system, a couple of pellicle beam splitters and optical mirrors are employed to generate two sheared off-axis beams from the single object beam by controlling the tilted angle of the optical mirror. Each sheared beam is divided into two areas with and without object data, which are called half-object and half-reference beams, respectively. These sub-divided object and reference beams then make interference patterns, just like the conventional two-arm holographic interferometer. This holographic interferometer system, called SA-OHI, can solve the DC bias, virtual and duplicated image problems occurred in most lateral shearing interferometers, which allow extraction of the hologram data only related to the target object. The operational principle of the proposed system is analyzed based on ray-optics. To confirm the feasibility of the proposed system in the practical application fields, experiments with test lenses are also carried out and the results are comparatively discussed with those of the conventional system.

Integrating information from two pictorial animations: Complexity and cognitive prerequisites influence performance

Abstract: Dividing visual attention between spatially distinct sources of information could either be beneficial (if there is too much information for a single visualization) or detrimental (if interrelated information has to be mentally re-integrated) for learning. We present a new display technology allowing for the presentation of two distinct animations by avoiding split foci of visual attention: learners are able to switch between animations by moving their head. We examined how 84 naive learners integrated information in three presentation modes: the ‘vexing-image’ mode displaying two animations, participants being able to switch between them without shifting the visual focus, a classical ‘split-screen’ and an ‘overlaid’ condition. Results showed that reduced complexity led to higher performance. Further, we showed that participants with high mental rotation abilities were best in the ‘split-screen’ mode, whereas participants with low mental rotation abilities benefited most from the ‘vexing-image’. Theoretical and instructional consequences of these findings are discussed. Copyright © 2010 John Wiley & Sons, Ltd.