December 2002
Volume 43, Issue 13
Free
ARVO Annual Meeting Abstract  |   December 2002
External Noise Methods and Observer Models
Z-L Lu; BA Dosher
Author Affiliations & Notes
  • Z-L Lu
    LOBES Department of Psychology University of Southern CA Los Angeles CA
  • BA Dosher
    MAPL Department of Cognitive Science University of California Irvine CA
  • Footnotes
    Commercial Relationships   Z. Lu, None; B.A. Dosher, None. Grant Identification: AFOSR, NIMH, NSF
Investigative Ophthalmology & Visual Science December 2002, Vol.43, 2915. doi:
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      Z-L Lu, BA Dosher; External Noise Methods and Observer Models . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2915.

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Abstract

Abstract: : Purpose: The external noise method and the linear amplifier model (LAM) reveal inefficiencies of the perceptual system.1 The LAM models threshold vs external noise contrast (TVC) functions at a single performance level, but generally fails to account for TVCs at different performance levels.2 We proposed a perceptual template model (PTM), an LAM elaborated with a non-linear transducer and internal multiplicative noise/contrast gain control, to model TVCs at multiple performance levels or full psychometric functions.2 A"triple-TVC" method ---measuring TVCs at three performance levels--- provides necessary constraints on observer models including the PTM. A different "double-pass" test3 measures performance twice with identical stimuli (signal + external noise). Response consistency assays the ratio of internal and external noise amplitude and therefore estimates total (multiplicative and additive) noise. Method: We analyze the mathematical properties of three observer models, the LAM, the PTM and the EAW4 (LAM+multiplicative noise + uncertainty) in relation to both the triple-TVC and double-pass paradigms. Results: We show (1) LAM can accommodate neither multiple-TVCs nor response consistency; (2) LAMs with uncertainty and a max decision rule can accommodate multiple-TVCs, but not response consistency; (3) Both PTM and EAW with substantial uncertainty can accommodate both multiple-TVCs and response consistency. Conclusion: The triple-TVC and double-pass methods provide complementary constraints on observer models. Both multiplicative noise and some form of nonlinearity (either substantial uncertainty or a nonlinear transducer function) are necessary to model existing data from triple-TVC and double-pass measurements. Implications for models of the mechanisms of attention and/or perceptual learning are discussed. 1Pelli, Dissertaion, 1981. 2Lu & Dosher, JOSA, 1999. 3Burgess & Colborne, JOSA, 1988. 4Eckstein, Ahumada & Watson, JOSA, 1997.

Keywords: 509 pattern vision • 364 computational modeling 
© 2002, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.
Copyright © 2024 Association for Research in Vision and Ophthalmology.
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