12/27/2023 0 Comments Visual memory pictures![]() In a study with three densely prosopagnosic patients, the evaluation of primary visual proficiency was done with a screening battery comprising all of the relevant visual cues, and the patients did show subtle impairments on several of the screening tasks. It has now been shown that there are highly selective disorders of color, luminance, shape, texture and glossiness that might interfere with visual recognition. George Ettlinger was subsequently criticized for using a composite sensory score and for using tests that might not have covered all of the relevant sensory abilities for visual recognition. The crux of his argument is that, although patients with a recognition deficit may have sensory impairments, other patients who do not experience recognition problems can show equal or worse impairments on the sensory tests. He carried out a careful assessment of sensory status in patients with and patients without recognition deficits, and he argued that sensory status alone could not explain the presence or absence of a recognition disorder. A seminal study by George Ettlinger in 1956 set out to test Bay's hypothesis. The debate is fuelled by the fact that even the most ‘‘pure’’ cases of agnosia often show some mild problems on tasks of visual perception. However, the question of whether subtle sensory impairment or a certain constellation of sensory deficits can produce the clinical symptoms of associative agnosia remains controversial. Also, it has now been clearly established that language difficulties are not instrumental in causing associative agnosias. More recent investigations have convincingly demonstrated that visual recognition disorders can occur in patients with normal, or even above average intelligence. Notably, Eberhard Bay claimed that the so-called higher order recognition deficits are secondary to sensory impairment, general intellectual loss, language problems, or a combination of these factors. It is the viability of the concept of associative agnosia, or as Hans-Lukas Teuber put it, ‘‘a normal percept stripped of its meaning’’ that has been questioned. A few years later, Sigmund Freud coined the term agnosia to describe these recognition disturbances. Regarding impairments in object recognition, Heinrich Lissauer suggested a distinction between apperceptive and associative Seelenblindheit, where the former results from visuosensory deficits, whereas the latter was thought to represent a difficulty in associating meaning with a relatively intact percept. Visual recognition disorders as a result of brain disease have created theoretical controversies since they were first described in the latter half of the 19th century. De Haan, in Reference Module in Neuroscience and Biobehavioral Psychology, 2017 Prosopagnosia and Sensory Status
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