City Research Online

Perceived pattern regularity computed as a summary statistic: implications for camouflage

Morgan, M. J., Mareschal, I., Chubb, C. and Solomon, J. A. (2012). Perceived pattern regularity computed as a summary statistic: implications for camouflage. Proceedings of the Royal Society B: Biological Sciences, 279(1739), pp. 2754-2760. doi: 10.1098/rspb.2011.2645

Abstract

Why do the equally spaced dots in figure 1 appear regularly spaced? The answer ‘because they are’ is naive and ignores the existence of sensory noise, which is known to limit the accuracy of positional localization. Actually, all the dots in figure 1 have been physically perturbed, but in the case of the apparently regular patterns to an extent that is below threshold for reliable detection. Only when retinal pathology causes severe distortions do regular grids appear perturbed. Here, we present evidence that low-level sensory noise does indeed corrupt the encoding of relative spatial position, and limits the accuracy with which observers can detect real distortions. The noise is equivalent to a Gaussian random variable with a standard deviation of approximately 5 per cent of the inter-element spacing. The just-noticeable difference in positional distortion between two patterns is smallest when neither of them is perfectly regular. The computation of variance is statistically inefficient, typically using only five or six of the available dots.

Publication Type: Article
Additional Information: Published in Proceedings of the Royal Society B: Biological Sciences.
Subjects: R Medicine > RE Ophthalmology
Departments: School of Health Sciences > Optometry & Visual Science
URI: http://openaccess.city.ac.uk/id/eprint/14136
[img]
Preview
Text - Accepted Version
Download (1MB) | Preview

Export

Downloads

Downloads per month over past year

View more statistics

Actions (login required)

Admin Login Admin Login