Journal article

The Use of the Cancellation Technique to Quantify the Hermann Grid Illusion

Piers DL Howe, Margaret S Livingstone



When observers view a grid of mid-gray lines superimposed on a black background, they report seeing illusory dark gray smudges at the grid intersections, an effect known as the Hermann grid illusion. The strength of the illusion is often measured using the cancellation technique: A white disk is placed over one of these intersections and the luminance of the disk is reduced until the disk disappears. Its luminance at this point, i.e., the disk's detection threshold, is taken to be a measure of the strength of the illusion. Our experiments showed that some distortions of the Hermann grid, which were sufficient to completely disrupt the illusion, did not reduce the disk's detection threshold. ..

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Awarded by NIH

Awarded by ARO

Funding Acknowledgements

This work was supported by a Helen Hay Whitney Foundation grant to P. H., and an NIH grant EY 13135 and an ARO grant 46961 to M. L. None of these sponsors played any role in the any part of the experiment or the manuscript preparation.