The role of visual salience in directing eye movements in visual object agnosia.

Journal article

When we look at a scene our scanning eye movements are not random [1]. Remarkably, different observers look at similar points in a given image. One explanation is that our understanding of the scene controls the paths our eyes take - so called 'top-down' control. An alternative possibility is that the visual system uses low-level 'bottom-up' features, such as edges, contrast or boundaries, to determine where the eyes land [2-4]. Fixated locations have been shown to contain higher values of 'low-level' visual features than non-fixated ones [2,3,5]. Moreover, biologically-plausible, low-level computational saliency maps produce scanpaths similar to those traced by human eye movements [4]. However, there is controversy about the role of bottom-up versus top-down control of eye movements [6,7]. To test between these possibilities, we measured the eye movements of two patients with visual agnosia who are severely impaired at recognizing objects or scenes, and therefore diverge from healthy volunteers in their understanding of the scene. Despite this, we found that, when inspecting a picture, their eyes look at the same locations as healthy individuals for the first few fixations. Initial eye movements, during a recognition task, therefore, are not affected by an impaired explicit understanding of the scene. © 2009 Elsevier Ltd. All rights reserved.

Authors: Mannan, S; Kennard, C; Husain, M

• Publication status: Published
• Journal: Current biology : CB
• Volume: 19
• Issue: 6
• Pages: R247-R248
• Publication date: 2009-03-01
• DOI: 10.1016/j.cub.2009.02.020
• EISSN: 1879-0445
• ISSN: 0960-9822
• Language: English
• Keywords: Eye Movements; Reference Values; Fixation, Ocular; Agnosia; Recognition (Psychology); Brain; Humans; Visual Perception