Acceso usuarios
Guillaume Giraudet, Corinne Roumes
Scenes of the outside world do not look like any artificial image. They exhibit a specific spatial frequency content and a global structure evocative of their category membership. This information characteristic of natural scenes leads to define the concept of scene spatial signature. What is the respective role of this specific global information related to the scene and of the local information related to the image components in a target localization task ? Two experiments investigate the relative weight of both levels of information. Results show that initially, when images are blurred, the global structure plays a major role. However, after a familiarization period, subjects start using the invariant distinctive features of the target to localize it regardless of the aspect of the scene. Analogous to the scene spatial signature, the local information distinguishing the target from its close environment defines the object spatial signature. This perceptual adaptation process frees subjects from having to rely on global information. Results show that perceptual strategies are not determined once and for all. The visual system is flexible and is able to juggle the various available information at both global and local levels to adapt to the demand.
