Scale-invariance for radial frequency patterns in peripheral vision.

Ania Zolubak, PhD candidate in Dr Garcia-Suarez’ Lab, presented a poster at the European Conference on Visual Perception in Trieste.

Scale-invariance for radial frequency patterns in peripheral vision.

Zolubak, A. B., Schmidtmann, G., Garcia-Suarez, L. 

Radial frequency (RF) patterns are sinusoidally modulated contours. Previous studies have shown that RF shape discrimination (RF vs circle) is scale-invariant, i.e. performance is independent of radius size when presented centrally.
This study aims to investigate scale-invariance in peripheral vision (0-20° nasal visual field, radius 1°, RF=6, SF=1 or 5cpd) by scaling radii according to the Cortical Magnification Factor (CMF) and its fractions (MF1=½, MF2=¼, MF3=1/8).
Results show that performance remains constant with eccentricity for CMF, MF1, MF2 and for two observers (N=4) for MF3. However, the average performance for MF2 was twice and for MF3 four times worse compared to CMF and MF1.
The scale-invariance found for larger stimuli indicates the involvement of global shape processing in the periphery. The higher, yet constant thresholds for smaller patterns suggest that the resolvability of the contours limits peripheral performance and may elicit processing by low-level mechanisms.