Abstract
Studies of symmetry perception have generally used two stimulus types: figural and dot patterns. While figural patterns are more ecologically valid as they contain both position and orientation information consistent with a figure, dot patterns allow for tighter control of positional information in the absence of orientation. Here we designed a novel stimulus – a wedge pattern – made of centrally aligned but randomly-positioned wedges that is object-like but also allows for full randomization of element locations. Using a 2IFC task, we examined symmetry detection in wedge patterns made of different number of wedges (Experiment 1). The wedge patterns contained either two (red, green) or three (red, green, yellow) colours, with respectively 50% and 33% wedges arranged symmetrically, the remaining wedges being randomly positioned. Stimulus conditions were: segregated (i.e., position-symmetric wedges were of one colour), non-segregated (i.e., symmetric wedges were of all colours, in equal number), and anti-symmetric (i.e., symmetric wedges mismatched in colour). In Experiment 2, we directly compared performance for our wedge patterns alongside dot-patterns previously used by Gheorghiu et al. (2016, Sci Reports, 6, 29287) on an age-diverse sample of participants. In both experiments we used two perceptual conditions: without and with attention-to-colour. We found that (a) performance was independent of the number of wedges, in line with findings from dot patterns. (b) Attention to colour greatly increased accuracy for the segregated condition in both wedge and dot patterns, and significatly decreased it for anti-symmetric wedge-patterns, but not for dot patterns. (c) Accuracy was lower for older than younger adults (67% vs. 73%) in the no-attention condition but comparable in the attention-to-colour condition. In conclusion, symmetry seems to be processed in a very similar way for wedge and dot patterns. Stronger effects of attention to colour for wedge patterns are most likely due to their figural status.