We therefore wished to determine the peripheral scaling properties for symmetry detection in terms of both peak sensitivity and spatial tuning range. Corballis and Roldan (1974), for example, found little difference between symmetry detectability at 0° and at about 6° eccentric. Most of these studies found, by various methods, that sensitivity declined with eccentricity by various methods, but the declines reported were surprisingly gradual if symmetry detection is considered as a position-based task. Previous studies have reported reduced detectability for static symmetry when the axis is placed in eccentric vision ( Julesz, 1971 Corballis & Roldan, 1974 Saarinen, 1988 Herbert & Humphrey, 1993 Saarinen, Rovamo, & Virsu, 1989 Barrett, Whitaker, McGraw, & Herbert, 1999).
![noise mapping and symetry noise mapping and symetry](https://www.mdpi.com/symmetry/symmetry-13-01748/article_deploy/html/images/symmetry-13-01748-g001.png)
In the current study, we provide more detailed analysis of the eccentricity properties and compare the eccentricity functions for static and dynamic reflection symmetry, again using unscaled noise. In a further exploration of unscaled noise, it was found that symmetry detection did not show the expected decline with eccentricity, either in sensitivity or summation width ( Tyler, 1999). Symmetry detection in dynamic noise showed a much narrower summation width with a noise mask ( Tyler et al., 1995). Tyler, Hardage, and Miller (1995) found that detection of static targets was possible for widths up to 6 arcmin for unscaled targets and with up to 64° of separation by a blank mask for eccentricity-scaled targets ( Tyler & Hardage, 1996). The function of separation represents the summation range over which symmetry can be perceived, and its width provides a measure of the symmetry summation width. In previous studies, we have investigated the detectability of static and dynamic symmetry around a central axis across varying distances of separation of the symmetric regions by a noise mask.
![noise mapping and symetry noise mapping and symetry](https://www.mdpi.com/symmetry/symmetry-12-01857/article_deploy/html/images/symmetry-12-01857-g011.png)
There has been extensive interest in the mechanisms of human symmetry processing ( Wagemans, 1995 Tyler, 1996b).
![noise mapping and symetry noise mapping and symetry](http://www.amzsaki.com/wp-content/uploads/2015/11/perlin_noise03_RENDEREDcrop.jpg)
Reflection symmetry is a visual property of relevance to humans because other humans and most animals have pronounced bilateral symmetry, while inanimate objects in the natural environment typically do not have obvious symmetry ( Julesz, 1971 Barlow & Reeves, 1979 Tyler, 1996a). These findings suggest that static and dynamic symmetry detection are supported by different neural mechanisms and that these mechanisms are relatively invariant across the retina, unlike known mechanisms of spatial processing. For long duration stimuli, the summation width was substantially greater in central vision but decreased with eccentricity, the first known visual function to exhibit such reverse magnification behavior (Tyler, 1999). The estimated summation width for static symmetry detection was approximately constant with eccentricity for short duration stimuli. The spatial summation width for symmetry processing was evaluated with randomization around the axis of symmetry. Duration thresholds for symmetry in dynamic noise fields were significantly higher (about 100 ms) than those for static symmetry detection (about 40 ms), despite the fact that the information was refreshed many times during the threshold presentation period.
![noise mapping and symetry noise mapping and symetry](https://d3i71xaburhd42.cloudfront.net/da776d80076cfc56a106089d6e1fe3a2579798b7/4-Figure3-1.png)
At a low detection criterion (60% correct), peak duration sensitivities were high and varied little (<0.2 log units) from 0° eccentricity to 10° eccentricity for either static or dynamic targets. Detection of the presence of bilateral symmetry was investigated at various retinal eccentricities for static and dynamic noise reflected around a vertical axis.