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PERCEPTUAL AND COMPUTATIONAL MECHANISMS OF
FEATURE-BASED ATTENTION
by
Jianwei Lu
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(NEUROSCIENCE)
December 2006
Copyright 2006 Jianwei Lu
Object Description
| Title | Perceptual and computational mechanisms of feature-based attention |
| Author | Lu, Jianwei |
| Author email | jianweil@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Thesis |
| Degree program | Neuroscience |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2006-10-12 |
| Date submitted | 2006 |
| Restricted until | Unrestricted |
| Date published | 2006-11-21 |
| Advisor (committee chair) | Itti, Laurent |
| Advisor (committee member) |
Biederman, Irving Qin, Peter |
| Abstract | Visual attention modulates visual processing along at least three dimensions: A spatial dimension which enhances the representation of stimuli within the focus of attention, a feature dimension thought to enhance attended visual features throughout the visual field and an object dimension by which attention enhance the whole object as a unit. In this thesis, we focus on the feature dimension by studying the feature-based attention.We investigated the overall perceptual consequences of feature-based attention, by using dual-task human psychophysics and two distant drifting Gabor stimuli to systematically explore 64 combinations of visual features (orientation and drift speed) and tasks (discriminating orientation or drift speed). The resulting single, consistent dataset suggests a functional model, which predicts a maximum-rule by which only the dominant product of feature enhancement and feature benefit by feature relevance may benefit perception. We also used fMRI to investigate whether feature-based attention is a specific form of object-based attention or a new type of lower feature based attentional selection. We studied the feature-based attentional enhancement in two conditions: either the two stimuli appeared to belong to same object or as two different objects. Results showed both in same-object condition and in different-object condition the four subjects consistently had significant enhancement of the ignored stimulus in early visual areas. Hence it indicated feature-based attentional enhancement exists even when two stimuli belong to two different objects, suggesting it is a new type of attentional selection which takes place in the low feature levels, not dependent on the objectness of the two features. We also present two unpublished studies showing that Gabor stimuli are not the suitable stimuli to trigger the feature-based attentional enhancement using fMRI.; In summary, this thesis provides a functional model to explain the overall psychophysical perceptual mechanism of the feature-based attention, and evidence that the feature-based attention is new kind of attentional selection biasing on the lower feature level. |
| Keyword | attention; psychophysics; fMRI; feature-based attention; object-based attention |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m186 |
| Rights | Lu, Jianwei |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Lu-20061121 |
| Archival file | uscthesesreloadpub_Volume14/etd-Lu-20061121.pdf |
Description
| Title | Page 1 |
| Full text | PERCEPTUAL AND COMPUTATIONAL MECHANISMS OF FEATURE-BASED ATTENTION by Jianwei Lu A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (NEUROSCIENCE) December 2006 Copyright 2006 Jianwei Lu |
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