Year: 2012
Type: dissertation
Abstract: We live in a visually rich environment yet our brains are only equipped to process a\nsmall fraction of all available information at any point in time. For successful and\nefficient perception, the brain relies on attention to differentiate and select specific\nstimuli for further analysis. Attention can be directed to features – feature based\nattention – which enhances the processing of other similar features independent of\nspatial location. I have recently shown that the benefits of feature-based attention not\nonly apply to lower-level features, but also to processes of object perception. The aim of\nthe thesis was to examine the behavioural and electrophysiological correlates\nunderlying the influence of feature-based attention on object perception. Chapter 1\nmeasured the electric field activity associated with attending to higher-level features\n(object contours) and comparing it with the neural activity while attending to motion\nstimuli. We found temporally later effects for contours relative to motion, suggesting that\nfeature-based attention to objects might be mediated by higher-tier visual areas, such\nas the lateral occipital cortex. In Chapter 2, I describe a study designed to investigate\nthe time course of neural activity while cueing attention within the feature dimension of\nshape that more directly targets higher-tier visual areas. Consistent with Chapter 1, I\niii\nfound temporally late modulation, but behavioural effects that were weaker than\nexpected. To account for these findings, I proposed a “wrong-turn” model which\nexplains the perceptual benefits and costs coupled to expecting the correct or incorrect\nfeature by taking into consideration the hierarchical structure of the visual system.\nMoreover, the model also makes specific predictions about the pattern of behavioural\nand electrophysiological activity while attending to features of varying complexity during\nobject perception. The aim of Chapter 3 was to test the predictions of the model; I cued\nattention to colour, a lower-level feature essential to perceiving the object. I found much\nstronger behavioural cueing effects, and a biphasic pattern (early and late) electric brain\nactivity that confirmed the predictions of the model. Together the results indicate that\nfeature-based attention plays an important role in object perception that is mediated by\na flexible perceptual system.
Source: TSpace (University of Toronto)
Author: Boge Stojanoski
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2761678020