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CHARACTERIZING THE PERCEPTUAL PERFORMANCE
OF A HUMAN OBSERVER
AS A FUNCTION OF EXTERNAL NOISE AND TASK DIFFICULTY
by
Seong-Taek Jeon
____________________________________________________________________
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
(PSYCHOLOGY)
August 2007
Copyright 2007 Seong-Taek Jeon
Object Description
| Title | Characterizing the perceptual performance of a human obseerver as a function of external noise and task difficulty |
| Author | Jeon, Seong-Taek |
| Author email | seongtaj@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Psychology |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2007-06-28 |
| Date submitted | 2007 |
| Restricted until | Unrestricted |
| Date published | 2007-08-07 |
| Advisor (committee chair) | Lu, Zhong-Lin |
| Advisor (committee member) |
Tjan, Bosco S. Wilcox, Rand Grzywacz, Norberto |
| Abstract | Discrimination or identification task performance is the joint function of many components, including signal contrast, external noise potency, template overlap (degree in which target stimuli are similar), as well as the state of the observer. Many observer models, including the Linear Amplifier model, the Perceptual Template model, and the Eckstein-Ahumada-Watson model, were constructed for cases where any single stimulus plausibly activates only one perceptual template (e.g., Gabor orientations of ±45°). In this research, we developed and evaluated a model to handle cases when close to-be-discriminated stimuli activate overlapping perceptual templates (e.g., Gabors of ±3°). Therefore, the model can predict both contrast as well as feature thresholds.; First, contrast threshold versus external noise contrast (TvC) functions were measured in an orientation identification task at fovea for four orientation differences (±3°, ±6°, ±15°, and ±45° from the vertical) across a range of external noises, using the method of constant stimuli (MCS) for three observers. TvC functions at multiple performance levels (65, 75, and 85% correct) were obtained for each orientation separation condition. The model provided excellent fits to the data in all conditions with changes of a single parameter that characterized the overlap between perceptual templates in different stimulus conditions. In other words, the gain of the perceptual template, the internal noises, and the non-linear transducer remain the same across different orientation conditions. The current model provides a general functional description of identification task performance in different signal contrast, external noise contrast, as well template overlap conditions.; In principle, the model also supports the estimation of feature thresholds. As seen from the first experiment, unfortunately, to measure extra thresholds in several external noise contrast levels requires large investment in data collection. |
| Keyword | psychophysics; discrimination; bayesian |
| 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-m752 |
| Rights | Jeon, Seong-Taek |
| 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-Jeon-20070807 |
| Archival file | uscthesesreloadpub_Volume44/etd-Jeon-20070807.pdf |
Description
| Title | Page 1 |
| Full text | CHARACTERIZING THE PERCEPTUAL PERFORMANCE OF A HUMAN OBSERVER AS A FUNCTION OF EXTERNAL NOISE AND TASK DIFFICULTY by Seong-Taek Jeon ____________________________________________________________________ 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 (PSYCHOLOGY) August 2007 Copyright 2007 Seong-Taek Jeon |
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