Historical And Medical Background Of Agnosia

Visual agnosia refers to the “…inability to recognize objects that results neither from general intellectual loss nor from a loss of basic sensory abilities,” (Anderson, 2009, p. 32). There are generally two types of visual agnosia: apperceptive agnosia and associative agnosia. Apperceptive agnosia is the inability to recognize or draw simple shapes as they are shown or represented. Associative agnosia is the ability to recognize and copy drawings of simple and complex shapes. However, person with associative agnosia are unable to recognize the complex objects (Anderson, 2009).

Throughout history, a human being was always reliant on the primary sensory areas. An ability to communicate and contract languages is considered to be a unique ability of human nation as no other species show an equal amount of complexity in terms of the structure and sound combination. On the other hand, primary visual cortex provides a skill set in order to identify the objects presented in the world, the distance towards them as well as to design a set of actions in order to incorporate some items such as a stone or a pen. The understanding of these systems is crucial, especially for those who suffer from strokes and tumors and as a result lost the ability to visually recognize objects or hear other people. This work will focus of the structure

Gibson’s and Gregory’s theories of perception both suggest that eye-retina is important for perception. The both believe that without eye-retina, a person will not be able to see. This is a common view of both of the theories of perception. The idea is supported by the case of SB. SB was a man who had been blind from birth due to cataracts. When he was 52, he had an operation which restored his sight and hence he could see. Thus, this case has shown the importance of eye-retina for things to be perceived. And therefore, supports both of theories of perception which eye-retina is essential for perception.

The first thing that I learned about perception was earlier discovered by a psychologist by the name of Max Wertheimer. He discovered that our body clearly separates images into figures

Dr. P, a musician and teacher who had developed visual agnosia, had difficulty processing what he sees, especially faces, he could only identify them by features which he remembered. He only completed tasks if he was singing, if interrupted, he could no longer remember what he was doing nor complete it. Sacks diagnosed Dr. P with prosopagnosia, the inability to identify

ABSTRACT: The aim of this paper is to defend a broad concept of visual perception, according to which it is a sufficient condition for visual perception that subjects receive visual information in a way which enables them to give reliably correct answers about the objects presented to them. According to this view, blindsight, non-epistemic seeing, and conscious visual experience count as proper types of visual perception. This leads to two consequences concerning the role of the phenomenal qualities of visual experiences. First, phenomenal qualities are not necessary in order to see something, because in the case of blindsight, subjects can see objects without experiences phenomenal

In Oliver Sacks’ The Man Who Mistook His Wife for a Hat, he denotes a “deficit is an impairment or incapacity of neurological function; such as loss of speech, loss of language, loss of memory, loss of vision loss of dexterity, or loss of identity” (Sacks, 1985). The specific neurological disorder that is highlighted in chapter one is Visual Agnosia, which is a deficit associated with poor primary visual processing that affects shape perception, figures, object, face and letter recognition (Serino, et al., 2014). Other subtypes of visual agnosia that also seemed to fit the descriptions that Sacks shared is prosopagnosia, which is the inability to recognize human faces (Shah, 2016), and pantomime agnosia, characterized as the inability to understand gestures (Gonzalez, Mack, & Heilman, K., 1986).

Neurological evidence points out that people who lose their eye sights accidently or by birth can certainly dream and imagine about things. Consciousness does not require interaction with the environment. This means that interaction, awareness, and emotions do not always fall in the category of consciousness. In this way, machines can be conscious if they acquire just few aspects (Shear, 1997).

Humans have a unique and wonderful device in how one sees. The eye and brain work together to turn the world into visual data one’s brain can understand and use. There are some eye conditions that inhibit the sight or the recognition of the shapes one sees. Research continues to overcome these conditions as well as to further understand the biochemical reaction that gives humans the sight and understanding one has of visual data. Included in the paper are some of the latest research methods.

As well as these, there is Developmental Agnosia - the inability to recognise objects from touch alone. Madeleine, a congenitally blind woman with cerebral palsy refers to her hands as useless lumps of dough that do not feel part of her, and was therefore unable to use them.

There are many facts that are unknown about the mind. For centuries, philosophers and scientists have tried to understand how it works. We have learned that the mind has a number of different levels of processing. Before Sigmund Freud “nearly all the previous research and theorizing of psychologists had dealt with conscious, such as perception, memory, judgment, and learning“ (Hunt185). Freud brought forth a number of theories that dealt with “the unconscious and its crucial role in human behavior”(Hunt 185). The unconscious is a storage area for information that is not being used. It is also the home of “powerful primitive drives and forbidden wishes that constantly generated pressure on the conscious mind”(Hunt

Vision is the most important sensory compared to other sensory modality therefore there is a wide range of research carried out on vision. Visual attention is defined as a term that portrays how individuals are able to change their view while attending to an image that is of a normal perspective due to the neurones in the cortex (Carasco, 2011). It is often described as a focal point which is situated with different locations in the region of space (Wright, 1998). Visual search requires detecting a specific target as quickly as possible. For example, trying to find your car in a large car park. By focusing our attention to the specific environment it improves our visual search of the target (Keane et al., 2015). The speed of a visual search

General visual agnosia is important to study because of how drastically it could change someone’s life. The example of the writer with alexia who lost the ability to process letters was particularly striking because his career relied on that ability. The concentration of a “visual center” for the processing of written languages and the fact that it can be temporarily affected are important in understanding other

Agnosia is defined as the inability to recognize objects through the processing of sensory information, which means there is no deficit in semantic memory or problems with naming objects. An individual suffering from agnosia still possesses all the relevant semantic information tied to a precept, but they cannot recognize the precept when it is presented to them and therefore trigger the recall of said information. There are many types of agnosia, but this essay will focus on visual object agnosia and prosopagnosia. The former is the inability to recognise objects: patients suffering from visual object agnosia do not have impaired vision, and in some cases can even copy the object they are seeing (patient H.J.A., Humphreys & Riddoch, 1987) or draw it from memory (patient D.F., Milner & Goodale, 1992), but are unable to recognize it when they see it. In the latter, prosopagnosia, patients cannot recognise faces of familiar individuals, and have to rely on other characteristics such as their voice or clothing to recognize them. Patients suffering from prosopagnosia can either acquire it through a lesion in relevant brain areas (acquired prosopagnosia) or for less understood reasons have it from birth, in which case it is termed developmental prosopagnosia. The study of patients with agnosia is integral to the field of visual recognition, as the specifics of their deficits can provide great insight into the ways our brain processes information; for example, the location of

Similarly, both theories are supported by research. Lawson and Humphreys (1996), for example, showed that recognition is affected more by tilt of major axis (foreshortening) than any other rotation, which endorses Marr’s and Nishihara prediction that establishing a central axis is crucial to the process of recognition. Warrington and Taylor (1978) reported that brain damaged patients could recognize objects presented in a typical view only. These patients found difficult to say if two photographs presented simultaneously were the same object when one image was a typical view and the other an unusual view. Although this could be explained as the patient’s inability to transform a 2D version of the atypical view into a 3D model, it could also be due to difficulty in establishing the central axis or due to some features of the object being hidden. In a later study, Humphreys and Riddoch (1984) used images where either the axis had been foreshortened through rotation or a critical feature was hidden. They found that patients had more problems recognizing the images with a foreshortened axis than the ones where a critical feature was hidden. Their