title: Overt attention in natural scenes: objects dominate features.
abstract: Whether overt attention in natural scenes is guided by object content or by low-level stimulus features has become a matter of intense debate. Experimental evidence seemed to indicate that once object locations in a scene are known, salience models provide little extra explanatory power. This approach has recently been criticized for using inadequate models of early salience; and indeed, state-of-the-art salience models outperform trivial object-based models that assume a uniform distribution of fixations on objects. Here we propose to use object-based models that take a preferred viewing location (PVL) close to the centre of objects into account. In experiment 1, we demonstrate that, when including this comparably subtle modification, object-based models again are at par with state-of-the-art salience models in predicting fixations in natural scenes. One possible interpretation of these results is that objects rather than early salience dominate attentional guidance. In this view, early-salience models predict fixations through the correlation of their features with object locations. To test this hypothesis directly, in two additional experiments we reduced low-level salience in image areas of high object content. For these modified stimuli, the object-based model predicted fixations significantly better than early salience. This finding held in an object-naming task (experiment 2) and a free-viewing task (experiment 3). These results provide further evidence for object-based fixation selection--and by inference object-based attentional guidance--in natural scenes.
authors.affiliation: Neurophysics, Philipps-University Marburg, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Stoll
authors.affiliation: Neurophysics, Philipps-University Marburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Thrun
authors.affiliation: School of Philosophy, Psychology and Language Sciences, Psychology Department, University of Edinburgh, UK.
authors.forename: Antje
authors.initials: A
authors.lastname: Nuthmann
authors.affiliation: Neurophysics, Philipps-University Marburg, Germany. Electronic address: wet@physik.uni-marburg.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Einhäuser
mesh_terms: D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D008962:Models, Theoretical; D010775:Photic Stimulation / Q000379:methods; D014796:Visual Perception / Q000502:physiology*
keywords: Attention; Eye movements; Fixation; Natural scenes; Proto-objects; Salience