[Effects of symmetry groups on complexity and goodness in visual pattern].

Two experiments were performed to investigate stimulus determinants of pattern complexity and pattern goodness. Two hundred and ninety-six undergraduates rated complexity and goodness of two-dimensional patterns, which consisted of solid and/or open circles. The patterns were invariant under transformations of reflection or rotation, and they formed cyclic groups or dihedral ones. The results were summarized as follows. (1) Goodness of patterns increased with the order of cyclic and dihedral groups with different weights. (2) Complexity of patterns having line-segments decreased with the order of cyclic and dihedral groups with equal weights, whereas that of patterns having no line-segments was medium regardless of the order. (3) Simplicity and goodness of patterns with a vertical axis of reflection were higher than those with the other orientation axes. (4) Patterns consisting of solid circles were rated more complex than those of open ones. (5) Complexity increased as a positively accelerated function of the number of circles, whereas goodness increased as a negatively accelerated function. It was concluded that complexity and goodness were determined by compound factors, which are processed at different stages of human visual system.