Turning the world around: patterns in saccade direction vary with picture orientation

The eye movements made by viewers of natural images often feature a predominance of horizontal saccades. Can this behaviour be explained by the distribution of saliency around the horizon, low-level oculomotor factors, top-down control or laboratory artefacts? Two experiments explored this bias by recording saccades whilst subjects viewed photographs rotated to varying extents, but within a constant square frame. The findings show that the dominant saccade direction follows the orientation of the scene, though this pattern varies in interiors and during recognition of previously seen pictures. This demonstrates that a horizon bias is robust and affected by both the distribution of features and more global representations of the scene layout.