An ERP component called the Sustained Posterior Negativity (SPN) indexes the brain response to regularity in visual patterns (e.g. vertical reflectional symmetry, horizontal reflectional symmetry or rotational symmetry). However it is unclear if different regularities are coded by independent or overlapping neural populations. Previous work has successfully exploited repetition effects to assess representational independence, and we adapted this approach to investigate visual regularity. Experiment 1 (N = 48) found that SPN amplitude increased when three reflectional symmetry patterns were presented sequentially. This SPN priming effect did not survive changes in retinal location (Experiment 2, N = 48) or non-orthogonal changes in axis orientation (Experiment 3, N= 48). However, SPN priming transferred between vertical and horizontal axis orientation (Experiment 4, N= 48) and between reflectional and rotational symmetry (Experiment 5, N= 48). We conclude that visual regularities at different retinal locations are coded independently. However, there is some overlap between different regularities presented at the same retinal location.

Here we consider reflectional (mirror) symmetry only, although it not the only type (Mach, 1886). In reflectional symmetry, there is a correlation between element position on either side of the axis (Barlow & Reeves, 1979). Therefore models of symmetry perception consider how local element position signals are integrated to

It is now possible for scientists to publicly catalogue all the data they have ever collected on one phenomenon. For a decade, we have been measuring a brain response to visual symmetry called the sustained posterior negativity (SPN). Here we report how we have made a total of 6674 individual SPNs from 2215 participants publicly available, along with data extraction and visualization tools (https://osf.io/2sncj/). We also report how re-analysis of the SPN catalogue has shed light on aspects of the scientific process, such as statistical power and publication bias, and revealed new scientific insights.

An Event Related Potential (ERP) component called the Sustained Posterior Negativity (SPN) is generated by regular visual patterns (e.g. vertical reflectional symmetry, horizontal reflectional symmetry or rotational symmetry). Behavioural studies suggest symmetry becomes increasingly salient when the exemplars update rapidly. In line with this, Experiment 1 (N = 48) found that SPN amplitude increased when three different reflectional symmetry patterns were presented sequentially. We call this effect ‘SPN priming’. We then exploited SPN priming to investigate independence of different symmetry representations. SPN priming did not survive changes in retinal location (Experiment 2, N = 48) or non-orthogonal changes in axis orientation (Experiment 3, N = 48). However, SPN priming transferred between vertical and horizontal axis orientations (Experiment 4, N = 48) and between reflectional and rotational symmetry (Experiment 5, N = 48). SPN priming is interesting in itself, and a useful new method for identifying functional boundaries of the symmetry response. We conclude that visual regularities at different retinal locations are coded independently. However, there is some overlap between different regularities presented at the same retinal location.