First of all it is important to give a general definition of the word ‘aphasia’. According to the New Oxford American Dictionary dictionary, aphasia is ‘the loss of ability to understand or express speech, caused by brain damage’. Psycholinguistics is indeed the study of language trough the speakers/listener’s brain.
There is a precise correlation between the damaged part of the brain and the kind of linguistic impairment: Broca’s aphasia results from damage to parts of the brain in front of the central sulcus while Wernicke’s aphasia results from damage to parts of the left cortex behind the central sulcus.
The main difference between Broca’s aphasia and Wernicke’s aphasia concerns fluency in the speech production. Broca’s aphasia is considered ‘nonfluent’ because it affects the speech production while Wernicke’s aphasia is considered ‘fluent’ because it affects only speech comprehension.
Broca’s aphasia, which is the most important of the less severe forms of nonfluent aphasias, is not only manifested in the slowness of the speech production but also in phonemic errors called ‘phonemic paraphasias’.
For example, a patient who wishes to produce the sentence in 1a would be likely to produce the sentence in 1b.
- I like the ice cream
- …. like … ice kleen
This shows not only that the patient changes the /r/ to /l/ in the word ‘cream’ in order to semplify the cluster but also that he/she omits the function words such as ‘I’ and ‘the’. The omission of these ‘little words’ is what bestowed the definition ‘telegraphic speech’ on the speech of Broca’s aphasics.
There are mainly two possible reasons for these omissions: either the economy of effort since the speech production is very effortful for these patients or the disturbance of syntactic competence. This second hypothesis, which is confirmed by the difficulty in judging the grammaticality and the meaning of sentences, would however undermine the idea that Broca’s aphasia is simply a production deficit.
Another important difference between the two aphasias is the fact that, in contrast to Wernicke’s aphasics, Broca’s aphasics are aware of their deficit. Wernicke’s aphasics don’t make any mistakes in speech production, however they rarely make any sense, since there is no coherence between the question asked and their reply, which shows a deficit in language comprehension.
E: How are you today, Mrs A?