Putting things into perspective: Which visual cues facilitate automatic extraretinal symmetry representation?

Objects project different images when viewed from varying locations, but the visual system can correct perspective distortions and identify objects across viewpoints. This study investigated the conditions under which the visual system allocates computational resources to construct view-invariant, extraretinal representations, focusing on planar symmetry. When a symmetrical pattern lies on a plane, its symmetry in the retinal image is degraded by perspective. Visual symmetry activates the extrastriate visual cortex and generates an Event Related Potential (ERP) called Sustained Posterior Negativity (SPN). Previous research has shown that the SPN is reduced for perspective symmetry during secondary tasks. We hypothesized that perspective cost would decrease when visual cues support extraretinal representation. To test this, 120 participants viewed symmetrical and asymmetrical stimuli presented in a frontoparallel or perspective view. The task did not explicitly involve symmetry; partici...