The following is a summary of “Contribution of higher-order structure to perception of mirror symmetry: Role of shapes and corners,” published in the January 2023 issue of Ophthalmology by Bellagarda, et al.


Visual mirror symmetry is a universal property that depends on certain low-level interactions between constituent parts. Higher-order structure between pairs of symmetric components that create virtual four-cornered forms may also be significant for supporting the perception of mirror symmetry. Originally envisioned as virtual lines between paired elements, the suggestion had been made. 

In a temporal integration paradigm, humans use corner elements created by connecting two Gabor elements along a central midline, producing vertices with varied internal angles. In patterns with symmetrically arranged pieces, it enabled them to explicitly modify the kind and degree of higher-order structure compared to the lower-order structure. 

Compared to patterns with just lower-order structures, they demonstrated a considerable contribution of higher-order structure to the prominence of visual symmetries. The temporal processing of higher-order vs lower-order patterns was shown to be the same, despite the fact that they are more sensitive to patterns with higher-order structures. 

The findings underscored the necessity for intricate models that can more easily reflect the complexity of real-world symmetries and have substantial implications for existing spatial filter models of symmetry perception that solely depend on lower-order structures.

Reference: jov.arvojournals.org/article.aspx?articleid=2785255