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Endogenous and exogenous visual attention: the interaction between bottom-up and top-down mechanisms

Wednesday, 22 June, 2011 - 17:00
Campus: Brussels Humanities, Sciences & Engineering campus
Faculty: Psychology and Educational Sciences
David Henderickx
phd defence

The studies in this dissertation contribute to the further development of models of visual selective
attention. After a comprehensive introduction in visual attention in chapter one, the current dissertation
presents several studies exploring the interactions between bottom-up and top-down attentional
processes in visual orienting. In chapter two, a first experimental study examined to what extent attention
driven by external stimuli (exogenous attention) and attention guided by a person’s own volition
(endogenous attention) share the processes responsible for feature binding in visual perception. The
study in chapter three focuses on the attentional phenomenon of ‘Inhibition of Return’ (IOR), which has
often been found with exogenous attention, and usually not with endogenous orienting. With the
introduction of an ‘endogenous split-cue’ paradigm, the results of the study support the claim that no IOR
is found with endogenous cues, because no bottom-up saliency-based orienting processes are involved
in most endogenous attention studies. In a third chapter, the susceptibility of the bottom-up attentional
phenomenon IOR for top-down strategic modulation is explored in both easy and more demanding
perceptual tasks.

In a fourth and fifth chapter, the conclusions from the current experimental research, each approaching
the interaction between top-down and bottom-up attentional processes from a different angle, were
combined and integrated into some of the leading frameworks of visual selective attention. Ultimately, an
adapted two-component attentional framework is presented, that will also serve as a basis for the
development of a computational vision system for the humanoid “Probo” in a parallel interdisciplinary
research project at the VUB.

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