ERP evidence for human early visual sensitivity to co-linearity compared to co-circularity

•We report behavioural and ERP measures to target detection.•Targets in co-linear sequences enhanced detection time and ERP peak latencies.•Targets in co-circular sequences enhanced ERP latencies at later processing stages.•The human brain optimises the processing of common natural geometric regularities.

Our complex visual environment is constrained by natural geometric regularities, including spatiotemporal regularity, co-linearity and co-circularity. To investigate human visual processing associated with these regularities we directly compared the neural processes in encoding dynamic co-linearity and co-circularity using event-related potentials (ERPs). By recording ERPs to a target bar presented alone (no context) or in a dynamic sequence of bars following a co-linear or co-circular path, we observed earlier ERPs to targets embedded in co-linear sequence at early (66 ms) and later stages (197 ms) of post-target processing. In contrast, targets in co-circular sequence only modulated ERPs at later stages of processing. It is proposed that early visual processing may have adapted to efficiently process co-linearity to improve target identification, whereas sensitivity to co-circularity does not occur until later stages of processing. These results have significant impact for understanding brain-behaviour relationships when processing natural geometric regularities.