Other studies also show changes between LO and FFA for the Rubin face-vase illusion
What are you looking at? Mechanisms of visual recognition.Barbara NordhjemVisual Neuroscience GroupLaboratory of Experimental OphthalmologyUniversity Medical Center Groningen
Human recognition • Gist of the scene at 7 images per second. • Unpredictable random QuickTime™ and a Sorenson Video 3 decompressor sequence of images are needed to see this picture.Potter 1971, 1975; Biederman 1972; Thorpe 1996 Movie by Jim DiCarlo
• Images change: object position, distance, pose, lighting and background clutter. Yet we know where to attend and what we are looking at.
Moving beyond V1• What happens at the cellular level after V1?
Gradual more complex preferred stimulus Tanaka, 1996
Parallel increase in invariance properties (position and scale)of neurons Illustration from Rousselet et al., 2004
Pathways in the brain• Lesions parietal lobe (Newcombe, 1969)• Ungerleider and Mishkin (1982) lesions in monkeys. Suggested regions organized in pathways• Goodale and Milner (1992) distinguish between perception and action Figure by Mike Cohen
• The case of DF: visual form agnosia • Carbon monoxide poisoning • Lesion of lateral occipital cortex
Are people attending to bothconstellations when they grasp?Patient (AT) with parietal lesions wasbetter grasping familiar than novelobjects – interaction of memory andaction control (Jeannerod et al.,1994). Aglioti et al., 1995
Modules in the brainProcessing areas withthe ventral pathway:Faces, Objects, Places Figure by Mike Cohen
Face and form agnosiaSome patients show a specific deficit for recognizing faces, others showdeficits for recognizing all other objects.Faces and objects are processed in separate, perhaps non-overlapping,brain areas.
Summary• Parallel increase in invariance to position and scale of neurons from V1 to IT• Specialized information processing• Dorsal and ventral pathways for action and perception• Keep in mind that the idea of pathways and specialized regions is simplified visualneuroscience.nl