Response normalization and blur adaptation:data and multi-scale model


Adapting to blurred or sharpened images alters perceived blur of a focused image (M. A. Webster, M. A. Georgeson, & S. M. Webster, 2002). We asked whether blur adaptation results in (a) renormalization of perceived focus or (b) a repulsion aftereffect. Images were checkerboards or 2-D Gaussian noise, whose amplitude spectra had (log-log) slopes from -2 (strongly blurred) to 0 (strongly sharpened). Observers adjusted the spectral slope of a comparison image to match different test slopes after adaptation to blurred or sharpened images. Results did not show repulsion effects but were consistent with some renormalization. Test blur levels at and near a blurred or sharpened adaptation level were matched by more focused slopes (closer to 1/f) but with little or no change in appearance after adaptation to focused (1/f) images. A model of contrast adaptation and blur coding by multiple-scale spatial filters predicts these blur aftereffects and those of Webster et al. (2002). A key proposal is that observers are pre-adapted to natural spectra, and blurred or sharpened spectra induce changes in the state of adaptation. The model illustrates how norms might be encoded and recalibrated in the visual system even when they are represented only implicitly by the distribution of responses across multiple channels.

Publication DOI:
Divisions: College of Health & Life Sciences > School of Optometry > Optometry
Additional Information: © ARVO. Creative Commons Attribution Non-Commercial No Derivatives License
Uncontrolled Keywords: physiological adaptation,adult,afterimage,astigmatism,contrast sensitivity,female,cular fixation,humans,biological models,photic stimulation,psychophysics,Ophthalmology,Sensory Systems
Last Modified: 06 Jun 2024 07:08
Date Deposited: 18 Apr 2012 13:06
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
http://www.jour ... /content/11/2/7 (Publisher URL)
PURE Output Type: Article
Published Date: 2011-02-09
Authors: Elliott, Sarah L.
Georgeson, Mark A (ORCID Profile 0000-0002-8173-9522)
Webster, Michael A.

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