Anna Hughes¹ (), Manjiri Bhat¹, Alasdair Clarke¹; ¹University of Essex

The visual foraging paradigm, where participants must search for multiple target exemplars in a display, allows us to study how human search behavior evolves in space and time. Previous work has shown that target properties, such as target complexity or salience, can affect foraging behavior in these tasks: we have also shown that spatial factors, such as target proximity, are important in accurately predicting which target a participant will select next. Here, we present a novel foraging experiment that explores how the layout of the foraging items influences the spatial strategies that participants use while foraging. We find the when items are placed on a cardinal grid, the foraging sequences and eye movement patterns generally follow the grid orientation. Rotating the grid to an oblique orientation leads to a preference for the oblique directions. However, the overall direction bias is stronger when the grid has a cardinal direction, suggesting that participants have an underlying preference for cardinal directions that goes beyond what is present in the stimulus. We develop a von Mises mixture model to account for these patterns of inter-item target selections. Finally, we incorporate this as a new component in our generative Bayesian model of foraging behavior (FoMo) and discuss our train-test split approach for assessing the accuracy of the model, and for determining the relative importance of different model parameters.