The missing-fundamental illusion at isoluminance

Kingdom, F.A. and Simmons, D.R. (1998) The missing-fundamental illusion at isoluminance. Perception, 27(12), pp. 1451-1460.

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The missing-fundamental illusion describes how a square wave with its fundamental Fourier component removed appears as a square wave. This illusion is normally explained with reference to the bandpass nature of the luminance-contrast-sensitivity function, together with a 'default-to-square-wave' rule. Since the chromatic-contrast-sensitivity function is low-pass, we should not expect a missing-fundamental illusion at isoluminance. Using a simultaneous-detection-and-identification paradigm to eliminate contrast as a cue to discrimination, we nevertheless found that chromatic missing fundamentals and square waves could not be separately identified at detection threshold: just under twice the contrast required to detect the stimuli was needed to identify them. To test whether this was due to insufficiently narrow chromatic-channel bandwidths, we measured detection and identification thresholds for chromatic F and 3F sine-wave gratings. In this case identification was possible almost at detection threshold, suggesting that channel bandwidth limitations were not the critical factor. It is suggested that the weak missing-fundamental illusion observed at isoluminance probably reflects the operation of mechanisms similar to those that are responsible for the chromatic Craik-Cornsweet illusion.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Simmons, Dr David
Authors: Kingdom, F.A., and Simmons, D.R.
College/School:College of Science and Engineering > School of Psychology
Journal Name:Perception

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