Word Blindness also known as Alexia Disorder is an acquired neurological disorder which is distinguished by one losing the ability to read or understand the written word. Alexia or Word Blindness comes in a variety of forms which are all caused by an incorrect formation of words during the process of oral reading which affect a reader’s perception and interpretation of the written word. The most common type of Word Blindness is Pure Alexia but there are also other types of this disorder such as Phonological Alexia, Deep Alexia, and Surface Alexia which all have different causes and influences on the minds ability to interpret what is being read.
Pure Alexia is the most common and recognizable forms of Alexia,these individuals maintain the ability to write, spell, and have normal language skills except that they often have a difficult time claiming words from their memory. Pure Alexia is caused by a lesion orlesions that cut off information that is normally received from visual cortex to the left angular gyrus. With Pure Alexia one may have difficulty recognizing written words or have issues with the identification of specific letters but often can identify words that are spelled aloud. Many people with this disorder have implemented a letter-by-letter reading technique which allows them to use their ability to name specific letters and identify small strings of letters to obtain the written word that their mind usually can’t comprehend.
Those with Phonological Alexia are governed by familiarity when it comes to their language skills. If one is accustomed to certain words then they are easily understood but if one comes in contact with a foreign word then it can’t be read or understood by the reader. With Phonological Alexia one is unable to read information through the process of sounding out each letter and word which makes things even more difficult. An additional challenge is that more abstract terms are less likely to be comprehended which limits their vocabulary to basic levels. Phonological Alexia is caused by variable lesions within the left middle cerebral artery or Superior temporal lobe.
Deep Alexia is a reading error that occurs when one interprets a word written as relating to the meaning in another context such as its synonym, antonym, subordinate ,super ordinate, attribute, or associate. Another common trait is a difficulty in using pronounceable non-word in reading Often there is also difficulty in reading words with affixes due to the substitution or deletion of letters in a word. The most common cause of Deep Alexia is extensive lesions which are in much of the left frontal lobe and can extend into the posterior lobe as well.
Surface Alexia patients rely upon the pronunciations of written words in order to understand their meanings. An effect of Surface Alexia is the inability for one to distinguish the difference between homophonic words or words that sound the same but have different meanings such as sea and see. These patients understand the word but cannot physically choose which option is correct when reading. Another issue with this disorder is that not only can a patient not recognize a words specific meaning but often it becomes unknown if the word is real until its pronunciation out loud. Patients with surface alexia typically have a lesion is the tempo parietal region of the left hemisphere of the brain.