# The brain does not process horizontal reflection when attending to vertical reflection, and vice versa

## TL;DR

The brain processes vertical and horizontal symmetry independently, without interference from the other.

## Contribution

The study shows that symmetry processing occurs in axis-specific channels, unaffected by orthogonal symmetry.

## Key findings

- The SPN amplitude was unaffected by orthogonal symmetry in distractor dots.
- Visual symmetry processing is axis-specific and independent.
- Replication of previous SPN findings was confirmed.

## Abstract

Previous work has found that feature attention can modulate electrophysiological responses to visual symmetry. In the current study, participants observed spatially overlapping clouds of black and white dots. They discriminated vertical symmetry from asymmetry in the target dots (e.g., black or white) and ignored the regularity of the distractor dots (e.g., white or black). We measured an electroencephalography component called the sustained posterior negativity (SPN), which is known to be generated by visual symmetry. There were five conditions with different combinations of target and distractor regularity. As well as replicating previous results, we found that an orthogonal axes of reflection in the distractor dots had no effect on SPN amplitude. We conclude that the visual system can processes reflectional symmetry in independent axis-orientation specific channels.