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Levels of breakdown in impaired word retrieval
Associate Professor Lyndsey Nickels Macquarie Centre for Cognitive Science (MACCS) Macquarie University, Sydney.
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4 people with word production impairments
NAME AGE DISORDER % CORRECT PICTURE NAMING ARTHUR 65 yrs Acquired aphasia 54% MARIE 8 yrs Developmental Language Impairment 65% CHRIS 47 yrs 25% BECCA 9 yrs 34% We will begin by giving examples of 4 individuals with poor word production. They all have word production impairments evident in conversation, and confirmed by poor accuracy on tests of picture naming. At this point we could simply decide to treat the naming impairment. However, the cognitive neuropsychological approach would argue that this would be inadequate….
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Cognitive Neuropsychology: An Assumption
Treatment will be maximally effective only when the direction of treatment is determined by precise knowledge of the individual’s processing strengths and weaknesses. Analysis limited to surface symptoms will not enable one to construct effective treatments because such symptoms can arise in various ways. The assumption of cognitive neuropsychology is… It is not enough to say that individuals have naming impairments – we need to understand why they cannot name. Only when we understand the causes of the surface symptoms (the word production impairments) will we be able to determine the most appropriate therapy to remediate those symptoms. How might we go about this? Well the first level of investigation is familiar to us all… rather than simply looking quantitatively at the naming accuracy, we can examine the types of errors produced.
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Arthur (acquired aphasia)
Spider -> “ant”
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Arthur (acquired aphasia)
Pocket -> “sleeve”
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Marie (developmental language impairment)
Pineapple -> “not apple juice, oh the fruit with the funky hairdo” From Best, 2005
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Chris (acquired aphasia)
Submarine -> /su:pbnn sbbri: sb mri:n/
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Chris (acquired aphasia)
Elephant -> /efl .. efltn lfnnt lfnnt lftn lfnt elfn eflnt /
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Becca (Developmental language impairment)
Hospital -> /hstəbəl/ From Best 2005
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Different error types in word retrieval
Arthur & Marie make semantic errors Arthur spider -> “ant” Marie Pineapple -> “not apple juice, oh the fruit with the funky hairdo” Chris & Becca make phonological errors Chris Submarine -> /su:pbnn sbbri: sb mri:n/ Becca Hospital -> / hstəbəl / WHY do these different error types occur? So when we look at their responses qualitatively we find that different error types occur. These distinctions, will I am sure be familiar to you. However, Semantic and phonological errors are still symptoms. The crucial point is not just to observe the different error types but to understand why they occur. The question is why are Arthur and Marie unable to retrieve the words they need and produce semantically related words instead and why are Chris and Becca unable to correctly pronounce the words they try to say? To understand this we need to understand how the language system works in those without language impairment.
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Picture naming tail purrs fur fins barks pet 4-legs d-o-g c-a-t d-o-g
Lexical semantics fins barks pet 4-legs d-o-g c-a-t d-o-g f-i-sh c-a-t f-i-sh Phonological output lexicon This diagram illustrates the processes that occur in word production in adults and children without language impairments. ….. How do semantic and phonological errors occur in this system? First, semantic errors… d o g a f a i c c sh t t Phonological output buffer cat Pic naming
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How do semantic errors occur?
Arthur Spider -> “ant” Marie Pineapple -> “the fruit with the funky hairdo” Semantic errors are most commonly attributed to semantic impairments ……. i.e. Impaired representation of word meanings Semantic errors are most commonly attributed to semantic impairments So in aphasia, some semantic features of the target may be lost or inadequately activated. In developmental cases the distinctive features may not have been acquired, and hence semantically related items may not have unique representations.
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spoken naming –sem deficit –threshold to phoneme level
Picture naming (with semantic impairment) tail purrs fur Lexical semantics fins barks pet 4-legs d-o-g f-i-sh c-a-t d-o-g d-o-g c-a-t f-i-sh Phonological output lexicon HOWEVER… THIS IS NOT THE ONLY WAY SEMANTIC ERRORS CAN ARISE…. d o g d o g f a i c sh t Phonological output buffer dog spoken naming –sem deficit –threshold to phoneme level
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spoken naming –sem deficit –threshold to phoneme level
Semantic errors (without semantic impairment) purrs tail fur Lexical semantics fins barks pet 4-legs d-o-g d-o-g d-o-g c-a-t c-a-t f-i-sh f-i-sh Phonological output lexicon If either there is a problem activating the representation of the target OR there is a problem with the representation itself, Then the next most highly activated d o g d o g f a i c sh t Phonological output buffer dog spoken naming –sem deficit –threshold to phoneme level
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Summary: Semantic errors
Two possible levels of impairment in spoken word production Semantic impairment Post semantic impairment Access to phonological representation (or loss of those representations) Semantic errors are a symptom which can have as their cause different underlying levels of impairment. How can we distinguish these different levels of impairment?
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How do we determine the underlying level of impairment?
- examine performance on other tasks that also use some of the processing components involved in word production. - if a person with language impairment can perform a task that utilises one of these components as accurately and as fast as a non-brain damaged person of the same age, education and culture, then it can be assumed that that component is not the source of the difficulty in word production.
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Heard Speech Print Pictures, seen objects Lexical Semantics
Phonological Output Lexicon Orthographic Output Lexicon Phonological Output Buffer Graphemic Output Buffer Speech output Writing
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Post-Semantic impairment
Print Heard Speech Post-Semantic impairment Speech output: Pictures, seen objects Lexical Semantics Phonological Output Lexicon Orthographic Output Lexicon Post-semantic impairment Will result in semantic errors in Speech output Phonological Output Buffer Graphemic Output Buffer Speech output Writing
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ok ok ok Post-semantic impairment Speech output:
Print Heard Speech Post-semantic impairment Speech output: (semantic errors) Written output: Speech comprehension: Written comprehension: (assuming no additional impairments) Pictures, seen objects ok Lexical Semantics ok Phonological Output Lexicon Orthographic Output Lexicon Phonological Output Buffer Graphemic Output Buffer ok Speech output Writing
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Speech comprehension:
Print Heard Speech Semantic impairment Speech output: Written output: Speech comprehension: Written comprehension: Pictures, seen objects Lexical Semantics Lexical Semantics Phonological Output Lexicon Orthographic Output Lexicon Phonological Output Buffer Graphemic Output Buffer Speech output Writing
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Semantic errors in all modalities Semantic impairment
Print Heard Speech Semantic impairment Speech output: (semantic errors) Written output: Speech comprehension: Written comprehension: Lexical Semantics Lexical Semantics Phonological Output Lexicon Orthographic Output Lexicon Phonological Output Buffer Graphemic Output Buffer Semantic errors in all modalities Speech output Writing
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semantic errors ok Summary Semantic impairment
Post-semantic impairment Speech output semantic errors Written output ok Speech comprehension Written comprehension Many people with aphasia have severe writing impairments – and indeed Arthur, the man we have been using the examples from was completely unable to write. In the case of developmental word finding problems the child may not yet have learned to read and spell. So what other means do we have of determining the level of impairment underlying the semantic errors? So to distinguish between semantic and post semantic impairments in patients who cannot write, we must examine their comprehension and specifically whether they make semantic errors in comprehension.
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Assessment of semantic processing in comprehension
Print Heard Speech Pictures, seen objects Require an assessment that has semantically related distractors Perform the assessment in both spoken and written forms Lexical Semantics Lexical Semantics How might we do this. Well there are a number of assessments that might be used The key things to remember is that semantic impairments result in impairments to both spoken and written comprehension. If only one modality is tested the problem could be due to an impairment at one of the o Phonological Output Lexicon Orthographic Output Lexicon Phonological Output Buffer Graphemic Output Buffer Speech output Writing
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Word-picture matching with semantically related distractors
Close semantic distractor Unrelated distractor Distant semantic distractor target Similar assessment of comprehension found in PALPA.
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Word-picture verification (a more sensitive test of semantic impairments)
Target (response: ‘yes’) Is this a pair of shoes? Semantically related distractor (response: ‘no’) Is this an aeroplane? Unrelated distractor (response: ‘no’ ) Is this a water melon?
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Pyramids & Palm trees (Howard & Patterson, 1992)
Arthur: 3 picture version: 87% 1 written word-2 pictures: % 1 spoken word-2 pictures: % Arthur therefore can be seen to make semantic errors in all modalities of comprehension as well as spoken word production and hence we can conclude that a semantic impairment underlies his spoken word production problem. Semantic impairment N=52 Controls score 94% correct or higher
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Marie (developmental language impairment)
Squirrel - nut test (Pitchford & Eames, 1994) 95% correct (within normal limits for age matched controls) British Picture Vocabulary Scale Standard Score 99 (average =100) Post-semantic impairment restricted to spoken word production
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Different error types in word retrieval
Arthur & Marie make semantic errors Arthur spider -> “ant” Marie Pineapple -> “not apple juice, oh the fruit with the funky hairdo” Chris & Becca make phonological errors Chris Submarine -> /su:pbnn sbbri: sb mri:n/ Becca Hospital -> / hstəbəl / So returning to our 4 examples…. Arthur & Marie’
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Different error types in word retrieval
Arthur & Marie make semantic errors Arthur spider -> “ant” Marie Pineapple -> “not apple juice, oh the fruit with the funky hairdo” Chris & Becca make phonological errors Chris Submarine -> /su:pbnn sbbri: sb mri:n/ Becca Hospital -> / hstəbəl / Semantic impairment Post-Semantic impairment So returning to our 4 examples…. Arthur & Marie make semantic errors, using the same method of investigation despite the fact that Marie has a developmental language impairment and Arthur acquired aphasia, we established that they have different underlying impairments. What is the impairment underlying the phonological errors produced by Chris and Becca?
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Unimpaired spoken naming –
Picture naming tail purrs fur Lexical semantics fins barks pet 4-legs d-o-g c-a-t d-o-g f-i-sh c-a-t f-i-sh Phonological output lexicon d o g a f a i c c sh t t Phonological output buffer cat Unimpaired spoken naming –
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Unimpaired spoken naming –
Picture naming (phonological errors) tail purrs fur Lexical semantics fins barks pet 4-legs d-o-g c-a-t d-o-g f-i-sh c-a-t f-i-sh Phonological output lexicon d o g a f a i c c sh t t Phonological output buffer cag ca_ Unimpaired spoken naming –
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Heard Speech Print Pictures, seen objects Repetition of nonwords
Lexical Semantics Sublexical reading Phonological Output Lexicon Orthographic Output Lexicon Phonological Output Buffer Graphemic Output Buffer Speech output Writing
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Phonological semantic ok ok ok ok Yes Yes No No No
Semantic impairment Post-semantic /lexical access Phonological output buffer Speech output Errors Semantic Phonological Written output semantic ok Speech comp. Written comp. Phonological errors in repetition & reading No Yes Length effect No No ok ok ok Yes
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Phonological ok Yes Chris Phonological output buffer Speech output
Errors Length effect Phonological Yes Written output ok Speech comp. Written comp. Phonological Errors in repetition & reading 1 syllable: 86% 3 syllable: 23% Naming Reading Repetition (words & nonwords)
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Chris – examples of errors across tasks
Submarine Pyramid Naming su:pbnn prmnt Reading sbrli:n prmdd Repetition sbmn prmmm
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How do we decide which treatment?
Each different level of breakdown in word production will be best remediated by a different type of treatment (e.g. Hillis & Caramazza, 1994; Nettleton & Lesser, 1991) impaired word meaning (semantics) → treatment focusing on meaning impaired retrieval of the phonological form from semantics → treatment focusing on providing/accessing the phonological form impaired phoneme level/phonological encoding treatment focusing on phonemes A widely accepted current hypothesis is that each different level of breakdown in word production will be best remediated by a different type of treatment (e.g. Hillis and Caramazza, 1994; Nettleton and Lesser, 1991). First we will look at semantic tasks, and in particular semantic tasks used to remediate semantic impairments. For example, a word-finding difficulty which has as its cause impaired word meaning (semantics) will require a treatment focusing on meaning (e.g. matching a word to one of a choice of pictures), whereas a problem retrieving the sounds of a word (phonology) will require a treatment focusing on word sounds (e.g. repeating a spoken word) (e.g. Miceli et al, 1996; Nettleton and Lesser, 1991).
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How do we decide which treatment?
Each different level of breakdown in word production will be best remediated by a different type of treatment (e.g. Hillis & Caramazza, 1994; Nettleton & Lesser, 1991) Do we have evidence that this approach works? Yes and No!! Well, yes and no.
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Do we have evidence that this approach works?
Developmental Literature Several studies have contrasted semantic and phonological tasks (e.g. Wing 1990, Hyde Wright et al. 1993) … with conflicting results BUT they have not identified the level of breakdown in the children treated AND examined the children as a group Hyde Wright et al (1993) semantic techniques bring about improvements in word finding phonological techniques did not. Wing (1990) phonological techniques brought about changes semantic did not!
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What treatment is appropriate?
Acquired Aphasia literature: Word retrieval impairments Tasks focusing on semantics and phonology - improve word retrieval e.g. Howard et al 1985 Nickels & Best 1996 Lexical Semantics Phonological Output Lexicon Phonological Output Buffer Speech
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What treatment is appropriate?
Acquired Aphasia literature: Word retrieval impairments All the tasks involve activation of both semantics and phonology But may focus more on semantics…. Lexical Semantics Phonological Output Lexicon Phonological Output Buffer Speech
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What treatment is appropriate?
Acquired Aphasia literature: Word retrieval impairments All the tasks involve activation of both semantics and phonology But may focus more on semantics or phonology Lexical Semantics Phonological Output Lexicon Phonological Output Buffer Speech Repeat “kangaroo” It starts with /k/
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What treatment is appropriate?
Acquired Aphasia literature: Word retrieval impairments All the tasks involve activation of both semantics and phonology They produce long lasting, item specific effects in the majority of individuals with impaired activation of the correct target in the phonological lexicon Improves likelihood of the target being sufficiently activated to be retrieved successfully. Lexical Semantics Phonological Output Lexicon This may be due to a semantic impairment or a post semantic impairment BUT individuals with more severe semantic impairments may not benefit as much (the correct items simply may not be activated in the phonological lexicon) So Arthur benefitted from this treatment – his word retrieval improved – BUT there was no effect on his comprehension as this did not improve his semantic impairment – merely made treated words more accessible in his semantic system. Phonological Output Buffer Speech
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What treatment is appropriate?
Acquired Aphasia literature: Semantic impairments The most successful therapy seems to involve exploring the semantic attributes of a stimulus. e.g. Boyle & Coelho, 1995. Coelho, McHugh & Boyle, 2000. Hillis, 1991, 1998. Nickels & Best, 1996. Lexical Semantics Phonological Output Lexicon Phonological Output Buffer Speech
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What treatment is appropriate?
Acquired Aphasia literature: Semantic impairments e.g. Nickels & Best (1996) AER (Arthur) “Relatedness judgements” (with feedback) Lexical Semantics Phonological Output Lexicon Phonological Output Buffer Speech Improved naming of treated and untreated stimuli
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What treatment is appropriate?
Acquired Aphasia literature: Treatment of phonological errors Relatively little adequate published work Franklin, Buerk, and Howard (2002) MB long sequences of phonologically related responses in all speech-production tasks Good monitoring ability therapy included phoneme discrimination tasks judgments of accuracy of target attempts Lexical Semantics Phonological Output Lexicon Franklin, Buerk, and Howard (2002) aimed to use the latter approach. MB produced long sequences of phonologically related responses in all speech-production tasks, however these rarely resulted in a correct response. Franklin et al. describe therapy that used an approach and tasks commonly used clinically when attempting to remediate self-monitoring (including phoneme discrimination tasks, judgements of accuracy of target attempts).11 However, they argue that the treatment (which showed generalised improvement across items and modalities) was not effective by improving self-monitoring, indeed they suggest (with hindsight) that MB had good monitoring. Rather, they propose that treatment improved the phoneme selection impairment itself Phonological Output Buffer Speech
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What treatment is appropriate?
Acquired Aphasia literature: Treatment of phonological errors Relatively little adequate published work Franklin, Buerk, and Howard (2002) MB generalised improvement across items and modalities they propose that treatment improved the phoneme selection impairment Lexical Semantics Phonological Output Lexicon Franklin, Buerk, and Howard (2002) aimed to use the latter approach. MB produced long sequences of phonologically related responses in all speech-production tasks, however these rarely resulted in a correct response. Franklin et al. describe therapy that used an approach and tasks commonly used clinically when attempting to remediate self-monitoring (including phoneme discrimination tasks, judgements of accuracy of target attempts).11 However, they argue that the treatment (which showed generalised improvement across items and modalities) was not effective by improving self-monitoring, indeed they suggest (with hindsight) that MB had good monitoring. Rather, they propose that treatment improved the phoneme selection impairment itself Phonological Output Buffer Speech
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Summary Identified (some of the) the different levels of breakdown that can underlie spoken word production impairments Semantic Post semantic Phoneme activation Demonstrated that there is evidence that treatment targeted at these levels of breakdown can be successful (at least in the acquired aphasia literature)
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Conclusions The Cognitive Neuropsychological approach requires..
Systematic assessment of the component processes of language processing In order to establish which of these processes are intact and which impaired Therapy will have the best chance of being successful only when the cause of the language symptom is understood These techniques can be applied to both developmental and acquired language disorders.
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