A visual illusion that influences perception and action through the dorsal pathway

摘要

There are two main anatomically and physiologically defined visual pathways connecting the primary visual cortex with higher visual areas: the ventral and the dorsal pathway. The influential two-visual-systems hypothesis postulates that visual attributes are analyzed differently for different functions: in the dorsal pathway visual information is analyzed to guide actions, whereas in the ventral pathway visual information is analyzed for perceptual judgments. We here show that a person who cannot identify objects due to an extensive bilateral ventral brain lesion is able to judge the velocity at which an object moves. Moreover, both his velocity judgements and his interceptive actions are as susceptible to a motion illusion as those of people without brain lesions. These findings speak in favor of the idea that dorsal structures process information about attributes such as velocity, irrespective of whether such information is used for perceptual judgments or to guide actions. Cristina de la Malla et al. show that an individual with extensive lesions to the ventral visual pathway can accurately judge the velocity at which an object moves despite not being able to correctly identify the object in question. This findings support a role of the dorsal visual pathway in judging velocity irrespective of perceptual processing.