Abstract
Research on scene recognition in normally-sighted people have shown the extent to which human observers use diagnostic image information such as colour, orientations or texture to quickly categorize natural images (Oliva 2005 Gist of the scene. In the Encyclopedia of Neurobiology of Attention. L. Itti, G. Rees, and J.K. Tsotsos (Eds.), Elsevier, San Diego, CA (pages 251–256) for a review). Even under degraded visual conditions such as low contrast, blurring or large visual eccentricity normally-sighted observers are able to categorize scenes quikly on the basis of their spatial properties.
In contrast to word and face perception, few investigations have been devoted to the understanding of how people with low vision perceive scenes (see Boucart et al. 2009 Visual neuroscience).
People with age related macular degeneration (acuity equal or lower than 1/20) were presented with coloured photographs of scenes. As we were interested in testing whether people with low vision can quickly grasp the gist of a scene, images were flashed for 300 ms either centrally or randomly in the 4 corners of a 21′ computer screen. In separate blocks of trials people were asked to categorize scenes on the basis of naturalness (natural/urban), temperature (hot/cold landscape) and indoor/outdoor.
Performance was above chance (65 to 78% hits) for temperature and naturalness respectively but at chance when the task was to decide if the scene was indoor or outdoor. Accuracy showed a ceiling effect for normally sighted controls. These results indicate that people with low vision can use image properties to recognize scenes and fail when categorization requires object identification (indoor/outdoor).