What happens in the first 200 ms of word reading : ERP studies on visual word recognition with top-down and bottom-up approaches /

In this thesis, three main questions were addressed using event-related potentials (ERPs): (1) the timing of lexical semantic access, (2) the influence of "top-down" processes on visual word processing, and (3) the influence of "bottom-up" factors on visual word processing. The timing of lexical semantic access was investigated in two studies using different designs. In Study 1,14 participants completed two tasks: a standard lexical decision (LD) task which required a word/nonword decision to each target stimulus, and a semantically primed version (LS) of it using the same category of words (e.g., animal) within each block following which participants made a category judgment. In Study 2, another 12 participants performed a standard semantic priming task, where target stimulus words (e.g., nurse) could be either semantically related or unrelated to their primes (e.g., doctor, tree) but the order of presentation was randomized. We found evidence in both ERP studies that lexical semantic access might occur early within the first 200 ms (at about 170 ms for Study 1 and at about 160 ms for Study 2). Our results were consistent with more recent ERP and eye-tracking studies and are in contrast with the traditional research focus on the N400 component. "Top-down" processes, such as a person's expectation and strategic decisions, were possible in Study 1 because of the blocked design, but they were not for Study 2 with a randomized design. Comparing results from two studies, we found that visual word processing could be affected by a person's expectation and the effect occurred early at a sensory/perceptual stage: a semantic task effect in the PI component at about 100 ms in the ERP was found in Study 1 , but not in Study 2. Furthermore, we found that such "top-down" influence on visual word processing might be mediated through separate mechanisms depending on whether the stimulus was a word or a nonword. "Bottom-up" factors involve inherent characteristics of particular words, such as bigram frequency (the total frequency of two-letter combinations of a word), word frequency (the frequency of the written form of a word), and neighborhood density (the number of words that can be generated by changing one letter of an original word or nonword). A bigram frequency effect was found when comparing the results from Studies 1 and 2, but it was examined more closely in Study 3. Fourteen participants performed a similar standard lexical decision task but the words and nonwords were selected systematically to provide a greater range in the aforementioned factors. As a result, a total of 18 word conditions were created with 18 nonword conditions matched on neighborhood density and neighborhood frequency. Using multiple regression analyses, we foimd that the PI amplitude was significantly related to bigram frequency for both words and nonwords, consistent with results from Studies 1 and 2. In addition, word frequency and neighborhood frequency were also able to influence the PI amplitude separately for words and for nonwords and there appeared to be a spatial dissociation between the two effects: for words, the word frequency effect in PI was found at the left electrode site; for nonwords, the neighborhood frequency effect in PI was fovind at the right elecfrode site. The implications of otir findings are discussed.

Autonomic prediction of error-related ERP components in perceptual and conceptual tasks in older and younger adults

In studies of cognitive processing, the allocation of attention has been consistently linked to subtle, phasic adjustments in autonomic control. Both autonomic control of heart rate and control of the allocation of attention are known to decline with age. It is not known, however, whether characteristic individual differences in autonomic control and the ability to control attention are closely linked. To test this, a measure of parasympathetic function, vagal tone (VT) was computed from cardiac recordings from older and younger adults taken before and during performance of two attentiondemanding tasks - the Eriksen visual flanker task and the source memory task. Both tasks elicited event-related potentials (ERPs) that accompany errors, i.e., error-related negativities (ERNs) and error positivities (Pe's). The ERN is a negative deflection in the ERP signal, time-locked to responses made on incorrect trials, likely generated in the anterior cingulate. It is followed immediately by the Pe, a broad, positive deflection which may reflect conscious awareness of having committed an error. Age-attenuation ofERN amplitude has previously been found in paradigms with simple stimulus-response mappings, such as the flanker task, but has rarely been examined in more complex, conceptual tasks. Until now, there have been no reports of its being investigated in a source monitoring task. Age-attenuation of the ERN component was observed in both tasks. Results also indicated that the ERNs generated in these two tasks were generally comparable for young adults. For older adults, however, the ERN from the source monitoring task was not only shallower, but incorporated more frontal processing, apparently reflecting task demands. The error positivities elicited by 3 the two tasks were not comparable, however, and age-attenuation of the Pe was seen only in the more perceptual flanker task. For younger adults, it was Pe scalp topography that seemed to reflect task demands, being maximal over central parietal areas in the flanker task, but over very frontal areas in the source monitoring task. With respect to vagal tone, in the flanker task, neither the number of errors nor ERP amplitudes were predicted by baseline or on-task vagal tone measures. However, in the more difficult source memory task, lower VT was marginally associated with greater numbers of source memory errors in the older group. Thus, for older adults, relatively low levels of parasympathetic control over cardiac response coincided with poorer source memory discrimination. In both groups, lower levels of baseline VT were associated with larger amplitude ERNs, and smaller amplitude Pe's. Thus, low VT was associated in a conceptual task with a greater "emergency response" to errors, and at the same time, reduced awareness of having made them. The efficiency of an individual's complex cognitive processing was therefore associated with the flexibility of parasympathetic control of heart rate, in response to a cognitively challenging task.

Electrophysiological constituents of the P100 and N170 ERP complex: De-constructing of face processing using independent component analysis and robust estimation.

The initial timing of face-specific effects in event-related potentials (ERPs) is a point of contention in face processing research. Although effects during the time of the N170 are robust in the literature, inconsistent effects during the time of the P100 challenge the interpretation of the N170 as being the initial face-specific ERP effect. The interpretation of the early P100 effects are often attributed to low-level differences between face stimuli and a host of other image categories. Research using sophisticated controls for low-level stimulus characteristics (Rousselet, Husk, Bennett, & Sekuler, 2008) report robust face effects starting at around 130 ms following stimulus onset. The present study examines the independent components (ICs) of the P100 and N170 complex in the context of a minimally controlled low-level stimulus set and a clear P100 effect for faces versus houses at the scalp. Results indicate that four ICs account for the ERPs to faces and houses in the first 200ms following stimulus onset. The IC that accounts for the majority of the scalp N170 (icNla) begins dissociating stimulus conditions at approximately 130 ms, closely replicating the scalp results of Rousselet et al. (2008). The scalp effects at the time of the P100 are accounted for by two constituent ICs (icP1a and icP1b). The IC that projects the greatest voltage at the scalp during the P100 (icP1a) shows a face-minus-house effect over the period of the P100 that is less robust than the N 170 effect of icN 1 a when measured as the average of single subject differential activation robustness. The second constituent process of the P100 (icP1b), although projecting a smaller voltage to the scalp than icP1a, shows a more robust effect for the face-minus-house contrast starting prior to 100 ms following stimulus onset. Further, the effect expressed by icP1 b takes the form of a larger negative projection to medial occipital sites for houses over faces partially canceling the larger projection of icP1a, thereby enhancing the face positivity at this time. These findings have three main implications for ERP research on face processing: First, the ICs that constitute the face-minus-house P100 effect are independent from the ICs that constitute the N170 effect. This suggests that the P100 effect and the N170 effect are anatomically independent. Second, the timing of the N170 effect can be recovered from scalp ERPs that have spatio-temporally overlapping effects possibly associated with low-level stimulus characteristics. This unmixing of the EEG signals may reduce the need for highly constrained stimulus sets, a characteristic that is not always desirable for a topic that is highly coupled to ecological validity. Third, by unmixing the constituent processes of the EEG signals new analysis strategies are made available. In particular the exploration of the relationship between cortical processes over the period of the P100 and N170 ERP complex (and beyond) may provide previously unaccessible answers to questions such as: Is the face effect a special relationship between low-level and high-level processes along the visual stream?

Blocking Top-down awareness of Kanizsa Figures: An ERP Investigation into Bottom-up Processing of Illusory Contours

Neural models of the processing of illusory contour (ICs) diverge from one another in terms of their emphasis on bottom-up versus top-down constituents. The current study uses a dichoptic fusion paradigm to block top-down awareness of ICs in order to examine possible bottom-up effects. Group results indicate that the N170 ERP component is particularly sensitive to ICs at central occipital sites when top-down awareness of the stimulus is permitted. Furthermore, single-subject statistics reveal that the IC N170 ERP effect is highly variable across individuals in terms of timing and topographical spread. The results suggest that the ubiquitous N170 effect to ICs found in the literature depends, at least in part, on participants’ awareness of the stimulus. Therefore a strong bottom-up model of IC processing at the time of the N170 is unlikely.

Método para la evaluación de riesgos en la implantación de un ERP

Tesis (Maestría en Informática Administrativa con Especialidad en Procesos Administrativos) U.A.N.L.

Procedimientos de implementación de un sistema ERP para la empresa que utiliza sistemas tradicionales

Tesis ( Maestría en Informática Administrativa) U.A.N.L.

Experiencias de una implantación exitosa en un sistema ERP R

Tesis (Maestría en Informática Administrativa con Especialidad en Administración de Información) U.A.N.L.

Attention! Prêt? On s’enTraine! Étude d’efficacité d’un programme d’entraînement intensif des processus attentionnels chez des jeunes ayant subi un traumatisme craniocérébral

Les dysfonctions attentionnelles suivant un traumatisme craniocérébral (TCC) compliquent souvent la reprise des activités de la vie quotidienne et influencent négativement le pronostic de réinsertion socio-académique et professionnelle. Or, les cliniciens de réadaptation disposent d’un nombre limité d’outils de remédiation cognitive dont l’efficacité est démontrée et qui sont adaptés à une population francophone. Cette étude vise à démontrer l’efficacité d’un protocole d’entrainement intensif des fonctions attentionnelles : « Attention! Prêt? On s’enTraine! » (Séguin, Lahaie & Beauchamp, 2012), basé sur une adaptation française de l’« Attention Process Training-I » (APT-I; Sohlberg & Mateer, 1987). Dix-sept participants ayant subi un TCC et présentant des déficits attentionnels ont reçu 15 séances d’entrainement attentionnel avec le programme « Attention! Prêt? On s’enTraine! » (n = 8) ou de l’aide aux devoirs (n = 9). Suite à l’intervention, les participants du groupe expérimental ont amélioré leur rendement dans plusieurs fonctions ciblées par l’intervention attentionnelle, notamment au niveau du balayage visuel, de l’attention sélective et de l’alternance attentionnelle. De plus, les gains se sont généralisés à des fonctions connexes, puisqu’une meilleure performance a été retrouvée dans des tâches de mémoire de travail, d’inhibition, de flexibilité cognitive et de planification visuoconstructive. La démonstration de l’effet positif d’un entrainement intensif sur le rendement attentionnel pourrait inciter les cliniciens et chercheurs à développer et à valider d’autres protocoles de remédiation cognitive francophones, pour les fonctions attentionnelles ou d’autres sphères de la cognition. Par le fait même, le pronostic fonctionnel de la clientèle pédiatrique en traumatologie en sera potentialisé.

Los beneficios de implementar un sistema ERP en las empresas colombianas – estudio de caso

El objeto de este trabajo es establecer, mediante el método de estudio de caso, los beneficios tangibles que para las empresas colombianas puede generar la implantación de un sistema ERP. Se inicia con la revisión del concepto de información, tecnología de información y sistemas de información. En esta parte se efectúa un recorrido teórico de la importancia de los sistemas de información y el diferente tratamiento que se ha dado a este concepto. En la segunda parte, se exploran los sistemas ERP, sus principales características, beneficios, factores críticos de éxito y costos de implantación. Finalmente, en la tercera parte, se presentan los resultados del estudio de caso sobre cinco empresas colombianas, que implementaron sistemas ERP, observando su desempeño individual y frente a las empresas de su subsector económico mediante el uso de 36 indicadores clasificados para medir liquidez, endeudamiento, rentabilidad, actividad y crecimiento.

Enseñanza de la pronunciación del español rioplatense (ERP) a hablantes de inglés americano general (IAG) : una propuesta innovadora.

Memoria de máster (Universidad de León, 2009). Incluye apéndices. Resumen basado en el de la publicación

Evaluación del mejoramiento del desempeño en los procesos financieros, administrativos, mediante la implementación de un sistema ERP empresarial

Este trabajo de investigación lo he realizado en cinco capítulos, los mismos que se resumen a continuación: En el primer capítulo se puede encontrar el marco conceptual donde se plantea un conocimiento del ERP como herramienta de control de recursos así también: el concepto, la base metodológica sobre el cual fue creado, la evolución de este tipo de sistemas. Abarcamos las razones del porque es importante el implementar este tipo de sistemas, describimos las ventajas y desventajas de su aplicación. El segundo capítulo se enfoca en determinar los factores que las empresas deben considerar como alertas para optar por la implementación de un ERP para el control de su información, la evaluación de las principales áreas financieras administrativas como son: ventas, compras, inventarios, activos fijos, flujos de caja, dentro de una organización excluyendo de este análisis al área de recursos humanos por tratarse de una área que abarca varias aristas que deben ser analizadas independientemente a detalle, vamos a evaluar los sistemas utilizados en cada área y las actividades básicas que las empresas mantienen en la actualidad para el control de sus operaciones. El tercer capítulo demuestra cómo se debe evaluar la implementación de un sistema ERP considerando un esquema de plan estratégico y utilizando la herramienta de mapas ubicar dentro de los procesos a la correcta implementación del sistema como base de la productividad, desarrollo y optimización de las áreas funcionales de la empresa. El cuarto capítulo analiza la mejora que se obtiene en cada área por la implementación, así como indicadores que permiten hacer seguimiento a todas las etapas del proyecto que permiten controlar las actividades realizadas. Además se realiza un análisis costo beneficio enfocándonos en los beneficios no tangibles que son parte de la implementación En el quinto capítulo tenemos las conclusiones y recomendaciones aplicables a este trabajo de investigación.

Análisis de la factibilidad de implementación de un sistema ERP, para el mejoramiento de los procesos empresariales. Caso: GGTUSA

El presente trabajo ha sido desarrollado con el propósito de establecer la factibilidad de implementar un sistema integrado ERP para la gestión operativa de la empresa GGTUSA, para lo cual se ha realizado un estudio, con el apoyo de todos los trabajadores de la compañía, conociendo cuales son los mecanismos de funcionamiento de cada una de las actividades desarrolladas en los diferentes procesos de la compañía. Partiendo de ese análisis interno de la compañía fue posible determinar cuáles son las necesidades más importantes para la automatización de sus procesos, en función de lo cual, se establecieron los lineamientos básicos para la selección de un sistema ERP, que se adapte a los requerimientos de la compañía. Considerando que la implementación de un sistema en una empresa es un tema que debe ser debidamente planificado, se han establecido los lineamientos básicos para la ejecución del “Proyecto de Implementación del Sistema ERP”, los cuales servirán a la Gerencia como estándares para ejecución planificada de la puesta en marcha del proyecto. El estudio de factibilidad del proyecto no podía concluir sin el análisis y evaluación financiera del mismo, estableciendo detalles como fuentes de financiamiento, definición de la inversión requerida o flujos de efectivo, análisis a través del cual fue posible determinar la rentabilidad del proyecto. Finalmente, una vez terminado el estudio, se ha podido concluir la factibilidad de implementación del sistema Integrado ERP, para la empresa GGTUSA.

Name agreement in picture naming: An ERP study

Name agreement is the extent to which different people agree on a name for a particular picture. Previous studies have found that it takes longer to name low name agreement pictures than high name agreement pictures. To examine the effect of name agreement in the online process of picture naming, we compared event-related potentials (ERPs) recorded whilst 19 healthy, native English speakers silently named pictures which had either high or low name agreement. A series of ERP components was examined: P1 approximately 120ms from picture onset, N1 around 170ms, P2 around 220ms, N2 around 290ms, and P3 around 400ms. Additionally, a late time window from 800 to 900ms was considered. Name agreement had an early effect, starting at P1 and possibly resulting from uncertainty of picture identity, and continuing into N2, possibly resulting from alternative names for pictures. These results support the idea that name agreement affects two consecutive processes: first, object recognition, and second, lexical selection and/or phonological encoding.