The saccadic flow baseline: Accounting for image-independent biases in fixation behavior

J Vis. 2017 Sep 1;17(11):12. doi: 10.1167/17.11.12.

Abstract

Much effort has been made to explain eye guidance during natural scene viewing. However, a substantial component of fixation placement appears to be a set of consistent biases in eye movement behavior. We introduce the concept of saccadic flow, a generalization of the central bias that describes the image-independent conditional probability of making a saccade to (xi+1, yi+1), given a fixation at (xi, yi). We suggest that saccadic flow can be a useful prior when carrying out analyses of fixation locations, and can be used as a submodule in models of eye movements during scene viewing. We demonstrate the utility of this idea by presenting bias-weighted gaze landscapes, and show that there is a link between the likelihood of a saccade under the flow model, and the salience of the following fixation. We also present a minor improvement to our central bias model (based on using a multivariate truncated Gaussian), and investigate the leftwards and coarse-to-fine biases in scene viewing.

MeSH terms

  • Attention / physiology*
  • Fixation, Ocular / physiology*
  • Humans
  • Models, Theoretical*
  • Probability
  • Saccades / physiology*
  • Visual Perception / physiology*