A Study On Congenital Visual Agnosia And Prosopagnosia

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).

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.

INTRODUCTION. Idiopathic congenital nystagmus, or idiopathic infantile nystagmus is a disease characterized by the rapid, involuntary eye movement. This movement is typically in the horizontal direction, however, movement in other directions have been observed. One way to get nystagmus is through genetic mutations. Nystagmus caused by genetic mutation is seen at a relatively young age but cannot yet be treated. The disease is not understood well, it is believed that the cause is a developmental defect. The linkage, and inheritance has not been identified, the patterns suggest that multiple genes are involved in the disease and that there are loci on different chromosomes with three of the five loci located on the X chromosome. Mutations have been linked to the FRMD7 gene, a gene that consists of 12 exons, of the FERM family. The function of FRMD7 have yet to be determined however an abundance of the protein in the brain in areas associated with the eye. Mutations within this region consist of missense, deletion, tranversion and nonsense mutations. Over forty-four mutations that lead to ICN have been found in the FRMD7 gene. Learning more about the mutation of FRMD7 in ICN is important because these mutations may prevent elongation of neurite processes during differentiation preventing axons from responding to stimuli (Watkins et al. 2012).

The following observation is of my own child. Isabel is seven years old and on this day she was playing with best friend at home. The other child is the same age, yet Isabel is quite taller and looks as if she is older. She wears glasses for her nearsightedness. Berger (2011) states is myopia – nearsightedness vision is the most common problem in middle childhood.

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

How do we know infants can see at birth? They can’t tell us. For this we depend on clues such as eye movement, light sensitivity and the appearance of the eye. Though an infant 's vision is present at birth the strength of their vision is far from mature. However, vision develops rapidly in infants, going from only being able to focus on images 4 to 30 inches away to a rapid ability to see details and shape (Berger, 2014). By 3 months these same infants with immature ability can see patterns color and motion. Surveys and medical research are regularly used to develop a better understanding of infant development.

Prosopagnosia is a condition where a person cannot recognise familiar faces, but only the features, not the whole face. The condition contradicts the model as it suggests that the process are most likely not separate. As most patients had severe problems with facial expression as well as facial identity, this suggests they are processed separately. The model can also be seen as reductionist, as it only gives a vague description of what the cognitive system does. However, there is research that does support the concept that there are two are separate paths for processing face recognition and facial expression. One being Humphreys, Avidan, and Behrmann (2007) who studied three participants with developmental prosopagnosia. All three had poor ability to recognise faces, but their ability to recognise facial expressions was similar to that of healthy

Individuals who suffer from developmental prosopagnosia have had impairments of face recognition since birth; nonetheless they have no sign of any neurological damage in their brain (Bate, Haslam, Jansari, & Hodgson, 2009, p. 392). Schmalzl, Palermo, Harris, & Coltheart (2009), stated that “the perception and recognition of faces is one of the most important function of our visual system, and given its importances face processing has become one of the more prominent areas of reseach in cognitive neuroscience” (p. 287). Sensory basis for prosopagnosia are important to be looked at, because it tells you what areas of the brain are associated.

A patient named D.F. suffered from this, and provided a great amount of support for Milner and Goodale’s theory. Although her low level visual functions such as target detection and colour discrimination were normal, her ability to recognize familiar faces and common objects was impaired. Yet when shown real objects rather than drawings, D.F. could recognize them. However, upon further examination of this ability it was found that D.F. was using surface properties such as colour, rather than the outline of the shape to identify the object (Humphrey et al 1994). What confirmed Milner and Goodale’s theory was that D.F. could grasp objects that she could not entirely perceive. Initial experiments by Milner et al (1991) highlighted this. In these D.F. was given a disc and had to perform either a perceptual orientation matching task or a visuomotor task. It was found that although she could not explain the orientation of the slot, her performance on the visuomotor task where she had to post the disc into the slot was typical. Milner and Goodale (1995) argued this was because D.F’s ventral stream was severely impaired, and the visuomotor skills she still had were due to an intact dorsal stream. This dissociation found between perception and action only increased the idea that the ventral and dorsal stream are independently working

New born infants have poor visual acuity as opposed to adults. Visual acuity measures to what extent an individual can detect visual detail. Their lack of visual acuity means they see the world a more ill-defined manner. Adult visual acuity is thirty times the visual acuity of a new born (Van Hof-van Duin & Mohn 1985). Atkinson & Bradrick (1981), supported this and found that new born infants could only detect the separation of lines if they are 30 times wider than the minimum width adults can detect. There is at least a five-fold improvement by 6 months of age in acuity, though it takes several years for it to reach adult level, Brown & Yamamoto 1986. New born infants also have poor visual accommodation, needed to make sharp retinal images at different distances.

Achromatopsia is a visual disorder characterized primarily by loss of visual acuity, nystagmus, photophobia and loss or reduction of the ability to distinguish colors; This autosomal recessive disease has an incidence of approximately 1: 30000 individuals and may occur immediately from birth or during the first months of life [4].

A parent may report or complain that his or her child is inattentive to visual stimuli, have poor reflexes and maybe show sign of sensitivity to light. A teacher may see the same behaviors in the academic setting. As school tasks become difficult and delay the educational progress, a referral should follow the chief complaint with a comprehensive vision evaluation by a medical ophthalmologist. Submission of the eye report to the school district along with observations and assessments will address accommodation and modification for the classroom setting if determined that the child qualifies as a child with a vision impairment. Some juveniles with treatable types of cataracts that have not progress to blindness will exhibit characteristics of cortical visual impairments. For example, a student who shows complications with contrast, visual acuity, sensitivity to light or need for increased lighting. Glare can also be a problem for a student with post-operative cataract

In another study that was conducted by Kimchi, Behrmann, Avidan and Amishav (2012), looked at how configural and featural data in congenital prosopagnosia (CP) interact with one another. Participants took part in Garner’s speeded classification task, which looks at

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

Additionally, such students are not able to effectively use gestures (Fan & Cheung, 2005). Most of the developmental steps of such chilren are delayed due to lack of vison. In emotional context, they may feel helplessness while interacting with others. These children can develop congnitive impairment because they they lack the integrating experience of association and classification and the understaning of these experiences. The other challenge faced with such children to develop their vocabulary. Sighted children can easily acquire these skills by reading, watching facial expressions and movements, but visually impaired children are unable to expereince this and it hinders their capability to improve their vocabulary. Physically, a visually impaired student is constantly rubbing their eyes and is always blinking. Frowning, squinting and holding books at close range are other characteristics of visually impaired individuals. Lastly, visually impaired learners are constantly complaining of dizziness, nausea, itchy eyes as well as blurred vision (Fan & Cheung, 2005).