Abstract/Details

Three studies on perception of texture -defined form and depth cue combination


2003 2003

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Abstract (summary)

In this thesis three studies are presented. The first study (Chapter 1) investigates the properties of 2nd-order spatial frequency channels. Here, the stimulus is a 2nd-order sine wave grating (or a sum of sine waves) formed by a pair of vertically and horizontally oriented texture images. We find modulation contrast sensitivity to be nearly flat over a five-octave range of spatial frequency, but band pass when stated as efficiency (relative to an idealized observer confronted with the same task). Increment threshold shows the improved performance with a sub-threshold pedestal seen in the “dipper effect,” but the typical Weber's law behavior at higher pedestal contrasts is not observed at the highest pedestal modulation contrasts achievable with our stimuli. Subthreshold summation experiments indicate that 2nd-order filters have a moderate bandwidth. The second study (Chapter 2) involves identification of 2nd-order letters. Using a critical-band masking paradigm we investigate the channels underlying identification of 2nd-order letters. We find that 2 nd-order letters are identified with a single, approximately 1.5 octave wide channel. This channel is fixed across different noise conditions indicating the inability of observers to look off-frequency. When the experiment is repeated at different viewing distances, we find that the channel frequency used to identify the letters changes proportionally with the letter frequency. In other words, scale invariance holds for 2nd-order letter identification. The third study is on depth cue combination. Through a slant adjustment task we investigate how two pictorial cues, linear perspective and texture, are combined allowing for the possibility of correlation between the two cues. Eight observers participated in this study. We find all observers' performance to be consistent with a weighted linear combination of the two cues. Further, we find three observers to be optimal, with uncorrelated cues, three other observers to be optimal with positive correlation among the two cues. The performance of the remaining two observers were consistent with suboptimal combination.

Indexing (details)


Subject
Psychology;
Experiments;
Ophthalmology
Classification
0623: Psychology
0623: Experiments
0381: Ophthalmology
Identifier / keyword
Health and environmental sciences; Psychology; Cue combination; Depth perception; Letter recognition; Spatial vision
Title
Three studies on perception of texture -defined form and depth cue combination
Author
Oruc, Ipek
Number of pages
165
Publication year
2003
Degree date
2003
School code
0146
Source
DAI-B 64/09, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Advisor
Landy, Michael S.
University/institution
New York University
University location
United States -- New York
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3105903
ProQuest document ID
305314143
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/305314143
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