Contributions to unsupervised and supervised learning with applications in digital image processing

311 p. : il.

Incidental Memory of Younger and Older Adults for Objects Encountered in a Real World Context

Effects of context on the perception of, and incidental memory for, real-world objects have predominantly been investigated in younger individuals, under conditions involving a single static viewpoint. We examined the effects of prior object context and object familiarity on both older and younger adults' incidental memory for real objects encountered while they traversed a conference room. Recognition memory for context-typical and context-atypical objects was compared with a third group of unfamiliar objects that were not readily named and that had no strongly associated context. Both older and younger adults demonstrated a typicality effect, showing significantly lower 2-alternative-forced-choice recognition of context-typical than context-atypical objects; for these objects, the recognition of older adults either significantly exceeded, or numerically surpassed, that of younger adults. Testing-awareness elevated recognition but did not interact with age or with object type. Older adults showed significantly higher recognition for context-atypical objects than for unfamiliar objects that had no prior strongly associated context. The observation of a typicality effect in both age groups is consistent with preserved semantic schemata processing in aging. The incidental recognition advantage of older over younger adults for the context-typical and context-atypical objects may reflect aging-related differences in goal-related processing, with older adults under comparatively more novel circumstances being more likely to direct their attention to the external environment, or age-related differences in top-down effortful distraction regulation, with older individuals' attention more readily captured by salient objects in the environment. Older adults' reduced recognition of unfamiliar objects compared to context-atypical objects may reflect possible age differences in contextually driven expectancy violations. The latter finding underscores the theoretical and methodological value of including a third type of objects-that are comparatively neutral with respect to their contextual associations-to help differentiate between contextual integration effects (for schema-consistent objects) and expectancy violations (for schema-inconsistent objects).

Do laptop ao jogo interacional: sentidos circulantes no Fórum de discussão do Programa Conexão Professor (2008-2010)

Esta pesquisa analisa os sentidos circulantes nos textos publicados (postagens) por professores e Moderadora no Fórum de discussão online do Programa Conexão Professor, desenvolvido pela Secretaria de Estado de Educação do Rio de Janeiro (SEEDUC). Parte de dois modos de objetivação das tecnologias da informação e da comunicação (TIC): uma, em que as TIC são apontadas como revolução tecnológica no contexto da sociedade da informação; e outra centrada na recontextualização educacional das TIC. Situa a distribuição de laptops para os professores da rede estadual de ensino no contexto do Programa citado, buscando apreender ambos nos termos do ciclo contínuo de políticas, de Richard Bowe e Stephen Ball. Trata o Fórum de discussão online como locus privilegiado e os textos nele produzidos, entre dezembro de 2008 e julho de 2010, como corpus. Assume como alternativa teórico-metodológica a Análise Crítica do Discurso (ACD), formulada por Norman Fairclough, elegendo como pontos de entrada: o controle interacional, as escolhas lexicais e a modalidade. Investiga, a partir das pistas discursivas detectadas nas postagens, as relações estabelecidas entre a proposta de incorporação das TIC e a totalidade do trabalho docente. Conclui que os sentidos postos em circulação contestam a centralidade atribuída às TIC, apontando a substituição tecnológica como tendência política atual, expressa pelo deslocamento da ênfase na discussão para o fornecimento de materiais prontos, denominados objetos de aprendizagem

Learning shape priors for single view reconstruction

In this paper, we aim to reconstruct free-from 3D models from a single view by learning the prior knowledge of a specific class of objects. Instead of heuristically proposing specific regularities and defining parametric models as previous research, our shape prior is learned directly from existing 3D models under a framework based on the Gaussian Process Latent Variable Model (GPLVM). The major contributions of the paper include: 1) a probabilistic framework for prior-based reconstruction we propose, which requires no heuristic of the object, and can be easily generalized to handle various categories of 3D objects, and 2) an attempt at automatic reconstruction of more complex 3D shapes, like human bodies, from 2D silhouettes only. Qualitative and quantitative experimental results on both synthetic and real data demonstrate the efficacy of our new approach. ©2009 IEEE.

Single trial learning of external dynamics: What can the brain teach us about learning mechanisms?

Humans have exceptional abilities to learn new skills, manipulate tools and objects, and interact with our environment. In order to be successful at these tasks, our brain has developed learning mechanisms to deal with and compensate for the constantly changing dynamics of the world. If this mechanism or mechanisms can be understood from a computational point of view, then they can also be used to drive the adaptability and learning of robots. In this paper, we will present a new technique for examining changes in the feedforward motor command due to adaptation. This technique can then be utilized for examining motor adaptation in humans and determining a computational algorithm which explains motor learning. © 2007.