Existing observer models developed for studies with the external noise paradigm are strictly applicable only to target detection or identification/discrimination of orthogonal target(s). We elaborated the perceptual template model (PTM) to account for contrast thresholds in identifying nonorthogonal targets. Full contrast psychometric functions were measured in an orientation identification task with four orientation differences across a wide range of external noise levels. We showed that observer performance can be modeled by the elaborated PTM with two templates that correspond to the two stimulus categories. Sampling efficiencies of the human observers were also estimated. The elaborated PTM provides a theoretical framework for characterizing joint feature and contrast sensitivity of human observers.
© 2009 Optical Society of America
Original Manuscript: December 18, 2008
Revised Manuscript: August 19, 2009
Manuscript Accepted: August 27, 2009
Published: October 5, 2009
Vol. 4, Iss. 13 Virtual Journal for Biomedical Optics
Seong-Taek Jeon, Zhong-Lin Lu, and Barbara Anne Dosher, "Characterizing perceptual performance at multiple discrimination precisions in external noise," J. Opt. Soc. Am. A 26, B43-B58 (2009)