Language and Cognition Colombo, June 2011 Day 8 Aphasia: disorders of comprehension

Auditory comprehension The ability to understand spoken language Affected to some degree in nearly everyone with aphasia, but severity and type of comprehension deficit varies

How do we understand heard words? Remember the PALPA model: Semantic System speech Auditory Phonological Analysis “yes, I hear speech sounds” Phonological Input Lexicon “yes, that’s a word” [o] [d] [g] /dog/

Levels of breakdown Speech sound perception/ analysis: Pure Word Deafness (very rare) Deficits at the Phonological Input lexicon or semantic system are much more common in aphasia Inability to understand the meaning of a heard word (even though they can repeat it correctly)

Feedback loops © Jianwu Dang

Assessing single word comprehension PALPA A series of subtests Can tell the clinician if the client’s primary breakdown is at the level of – Phoneme perception – Word recognition – Auditory short term memory – Semantic system Pointing tasks Use different modalities of input Control for error types

E.g. to see if phonological input lexicon is damaged: Show me bat Phonological input lexicon

Examples of pointing tasks

Evaluating semantic knowledge If the client is able to recognize words, how good is s/he at accessing meanings and concepts associated with words? Sometimes there is no problem with speech sound perception, no problem with word recognition, but some “fuzziness” in finding the meanings of words Compare to semantic paraphasias in production

Pyramids and Palm Trees

Six different versions of the test can be created – Three pictures – Three words – Say (or read) a word – choose which of two pictures is most closely related – Look at a picture – decide which of two spoken (or written) words is most closely related Using different input and output modalities can help understand the client’s deficit more clearly E.g., if a patient does better on picture-picture than spoken word-picture condition, that suggests that semantic knowledge is probably good but there is a problem accessing that knowledge from auditory input routes

Comprehension at phrase and sentence level More about this tomorrow Similar to the process of understanding words: Must process the incoming acoustic signal Must recognize phonemes and words Must associate words with semantic representations But ALSO must understand how the structure of the phrase affects meaning

Pragmatic comprehension deficits It is not enough to understand the meanings of sentences / utterances We also have to interpret the sentence meanings within a social and cultural context E.g. “You are standing on my foot” What s an appropriate response? – Yes, that is correct – So sorry! (and get off foot)

Pragmatic comprehension deficits Not really a problem with language A problem with performance, not competence Can happen even when all the steps in auditory comprehension work well This is because pragmatics relies not only on language skill, but also on other cognitive systems: memory, attention, social awareness, Theory of Mind….. More about cognitive communication deficits on Saturday morning

Intervention Not only working on comprehension – also expressive language Understanding language as a whole system If there are problems with semantics, work on semantics (in all modalities) If there are problems with phonological knowledge, work on phonology Evidence shows that best results happen when we combine approaches

Combined approaches E.g. combining semantic and phonological treatments –Marshall et al 1998: a combination of semantic comprehension tasks and phonological judgment tasks for a subject with verb naming impairment  Improvements in naming trained verbs and use of sentences containing those verbs –Spencer et al 2000: target pictures provided, with semantic category and a rhyming word  improvement in naming both trained and untrained items

Semantic treatment Treating at the semantic level –Picture sorting tasks –Similarities and differences within semantic categories –Semantic feature matrix fruit grows on trees red or green for eating (category) (property) (function)

Phonological treatment Treating at the phonological lexicon level –Find strategies that support production (by the client) / comprehension (by the communicative partner) of the desired word E.g. spelling the word out, short circumlocution, pause, gesture, drawings etc The strategy should be productive – if not, it should be withdrawn and replaced Treating at the phonological assembly (buffer) level –Repetition –Reading –Phonemic cuing

Phonological judgment tasks

Intervention for comprehension difficulties Schuell’s simulation approach Language is still functioning, just requires more “stimulation” Uses repetitive and controlled auditory stimuli Client responses MUST be given – asking the patient to point to a specific object (pointing drills) – Yes-No Questions (general knowledge, semantic knowledge, questions specific to a conversation / reading / activity – Reading Tasks: matching a word or sentence to a picture

Intervention Psycholinguistic approach: the idea is to enhance activation of linguistic representations Cross-modality priming: hearing a word makes it faster and easier to read a related word So we know from psycholinguistic experiments that it’s a good idea to approach language deficits in different modalities So: combine modalities, combine approaches