|
Simultanagnosia (or simultagnosia) is a rare neurological disorder characterized by the inability of an individual to perceive more than a single object at a time. This type of visual attention problem is one of three major components (the others being optic ataxia and optic apraxia) of Bálint’s syndrome, an uncommon and incompletely understood variety of severe neuropsychological impairments involving space representation (visuospatial processing). The term “simultanagnosia” was first coined in 1924 by Wolpert to describe a condition where the affected individual could see individual details of a complex scene but failed to grasp the overall meaning of the image.〔Farah, M.J. (1990). Visual agnosia. Disorders of object recognition and what they tell us about normal vision. Cambridge, MA: MIT Press.〕 Simultanagnosia can be divided into two different categories: dorsal and ventral. Ventral occipito-temporal lesions cause a mild form of the disorder, while dorsal occipito-parietal lesions cause a more severe form of the disorder. ==Description== Patients with simultanagnosia, a component of Bálint's syndrome, have a restricted spatial window of visual attention and cannot see more than one object at a time in a scene that contains more than one object.〔Jackson, G. M., Shepherd, T., Mueller, S. C., Husain, M., & Jackson, S. R. (2006). Dorsal simultanagnosia: An impairment of visual processing or visual awareness? (). Cortex, 42(5), 740-749.〕 For instance, if presented with an image of a table containing both food and various utensils, a patient will report seeing only one item, such as a spoon. If the patient's attention is redirected to another object in the scene, such as a glass, the patient will report that they see the glass but no longer see the spoon.〔Coslett, H. B., & Lie, G. (2008). Simultanagnosia: When a rose is not red. (). ''Journal of Cognitive Neuroscience'', 20(1), 36-48.〕 As a result of this impairment, simultanagnosic patients often fail to comprehend the overall meaning of a scene. In addition, patients note that one stationary object may spontaneously disappear from view〔 as they become aware of another object in the scene.〔Duncan, J., Bundesen, C., Olson, A., Humphreys, G., Ward, R., Kyllingsbaek, S., et al. (2003). Attentional functions in dorsal and ventral simultanagnosia. (). Cognitive Neuropsychology, 20(8), 675-701.〕 Simultanagnosic patients often exhibit a phenomenon known as “local capture” where they only identify the local elements of stimuli containing local and global features. However, recent studies have demonstrated that implicit processing of the global structure can occur.〔Jackson, G., Swainson, R., Mort, D., Masud, H., & Jackson, S. (2004). Implicit processing of global information in Bálint’s syndrome. (). Cortex, 40(1), 179–180.〕 With the appropriate stimulus conditions, explicit processing of the global form may occur.〔Dalrymple, K. A., Kingstone, A., & Barton, J. J. S. (2007). Seeing trees OR seeing forests in simultanagnosia: Attentional capture can be local or global. (). Neuropsychologia, 45(4), 871-875.〕 For example, a study performed with Navon hierarchical letters, which are large letters composed of smaller ones, revealed that the use of smaller and denser Navon letters biased the patient towards global processing.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Simultanagnosia (or simultagnosia) is a rare neurological disorder characterized by the inability of an individual to perceive more than a single object at a time. This type of visual attention problem is one of three major components (the others being optic ataxia and optic apraxia) of Bálint’s syndrome, an uncommon and incompletely understood variety of severe neuropsychological impairments involving space representation (visuospatial processing). The term “simultanagnosia” was first coined in 1924 by Wolpert to describe a condition where the affected individual could see individual details of a complex scene but failed to grasp the overall meaning of the image.Farah, M.J. (1990). Visual agnosia. Disorders of object recognition and what they tell us about normal vision. Cambridge, MA: MIT Press. Simultanagnosia can be divided into two different categories: dorsal and ventral. Ventral occipito-temporal lesions cause a mild form of the disorder, while dorsal occipito-parietal lesions cause a more severe form of the disorder. ==Description==Patients with simultanagnosia, a component of Bálint's syndrome, have a restricted spatial window of visual attention and cannot see more than one object at a time in a scene that contains more than one object.Jackson, G. M., Shepherd, T., Mueller, S. C., Husain, M., & Jackson, S. R. (2006). Dorsal simultanagnosia: An impairment of visual processing or visual awareness? (). Cortex, 42(5), 740-749. For instance, if presented with an image of a table containing both food and various utensils, a patient will report seeing only one item, such as a spoon. If the patient's attention is redirected to another object in the scene, such as a glass, the patient will report that they see the glass but no longer see the spoon.Coslett, H. B., & Lie, G. (2008). Simultanagnosia: When a rose is not red. (). ''Journal of Cognitive Neuroscience'', 20(1), 36-48. As a result of this impairment, simultanagnosic patients often fail to comprehend the overall meaning of a scene.In addition, patients note that one stationary object may spontaneously disappear from view as they become aware of another object in the scene.Duncan, J., Bundesen, C., Olson, A., Humphreys, G., Ward, R., Kyllingsbaek, S., et al. (2003). Attentional functions in dorsal and ventral simultanagnosia. (). Cognitive Neuropsychology, 20(8), 675-701.Simultanagnosic patients often exhibit a phenomenon known as “local capture” where they only identify the local elements of stimuli containing local and global features. However, recent studies have demonstrated that implicit processing of the global structure can occur.Jackson, G., Swainson, R., Mort, D., Masud, H., & Jackson, S. (2004). Implicit processing of global information in Bálint’s syndrome. (). Cortex, 40(1), 179–180. With the appropriate stimulus conditions, explicit processing of the global form may occur.Dalrymple, K. A., Kingstone, A., & Barton, J. J. S. (2007). Seeing trees OR seeing forests in simultanagnosia: Attentional capture can be local or global. (). Neuropsychologia, 45(4), 871-875. For example, a study performed with Navon hierarchical letters, which are large letters composed of smaller ones, revealed that the use of smaller and denser Navon letters biased the patient towards global processing.」の詳細全文を読む スポンサード リンク
|