This article was downloaded by: [Georgetown University] On: 14 March 2013, At: 23:13 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Aphasiology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/paph20 Investigating the effect of a semantic therapy on comprehension in aphasia Julie Morris a & Sue Franklin b a Speech and Language Sciences, Newcastle University, Newcastle, UK b Clinical Therapies, University of Limerick, Limerick, Ireland Version of record first published: 01 Aug 2012. To cite this article: Julie Morris & Sue Franklin (2012): Investigating the effect of a semantic therapy on comprehension in aphasia, Aphasiology, 26:12, 1461-1480 To link to this article: http://dx.doi.org/10.1080/02687038.2012.702885 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.tandfonline.com/page/terms-and- conditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
Transcript
This article was downloaded by: [Georgetown University]On: 14 March 2013, At: 23:13Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
AphasiologyPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/paph20
Investigating the effect of a semantictherapy on comprehension in aphasiaJulie Morris a & Sue Franklin ba Speech and Language Sciences, Newcastle University,Newcastle, UKb Clinical Therapies, University of Limerick, Limerick, IrelandVersion of record first published: 01 Aug 2012.
To cite this article: Julie Morris & Sue Franklin (2012): Investigating the effect of a semantictherapy on comprehension in aphasia, Aphasiology, 26:12, 1461-1480
To link to this article: http://dx.doi.org/10.1080/02687038.2012.702885
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make anyrepresentation that the contents will be complete or accurate or up to date. Theaccuracy of any instructions, formulae, and drug doses should be independentlyverified with primary sources. The publisher shall not be liable for any loss, actions,claims, proceedings, demand, or costs or damages whatsoever or howsoever causedarising directly or indirectly in connection with or arising out of the use of thismaterial.
Investigating the effect of a semantic therapyon comprehension in aphasia
Julie Morris1 and Sue Franklin2
1Speech and Language Sciences, Newcastle University, Newcastle, UK2Clinical Therapies, University of Limerick, Limerick, Ireland
Background: While evidence on the use of semantic therapy to improve word retrievalhas increased (Whitworth, Webster, & Howard, 2005), the impact of semantic therapyon comprehension itself has not been studied in depth. This paper reports on a specificsemantic therapy, which aims to improve access to semantic information. Data from twoparticipants, JAC and AD, are presented.Aims: The study aimed to examine the effectiveness of a specific semantic therapy oncomprehension of treated and untreated items, and on related tasks, thereby examininggeneralisation of any improvement to both items and tasks involving semantic process-ing.Methods & Procedures: The participants’ comprehension was assessed in detail prior totherapy. Measures were repeated over time to ensure any improvement seen could not bedue to more general recovery mechanisms. The two participants then took part in ther-apy which aimed to improve their comprehension, using a picture name verification task.Following therapy, relevant assessments were repeated to examine the effects of therapy.The study uses single case methodology with comparison across two similar cases.Outcomes & Results: JAC and AD responded differently to the semantic therapy; JAC’sauditory comprehension performance improved and this was regardless of whether itemshad been treated or not. In contrast, despite having a broadly similar profile of languageability, AD’s performance did not change. Potential reasons for this are explored withinthe paper.Conclusions: This paper provides a much needed demonstration of semantic therapy forcomprehension problems. One specific therapy is tested, rather than the combined ther-apies used in the existing literature. It considers the extent to which therapy generalisesto untreated words. It is clear that further research is needed regarding finer differentialdiagnosis, and ultimately, the impact of therapy on everyday comprehension for theseindividuals.
Many adults with aphasia have difficulties understanding the specific meanings ofwords; that is, accessing lexical semantic information about words. A semantic deficitaffects all modalities of processing (Whitworth et al., 2005) and is arguably the most
Address correspondence to: Dr Julie Morris, Speech and Language Sciences, Newcastle University,Newcastle Upon Tyne, NE1 7RU, UK. E-mail: [email protected]
Our thanks go to both AD and JAC and their families for their tremendous enthusiasm and involvementwith this project. Thanks to David Howard and Janet Webster for helpful comments on earlier versions ofthis paper.
debilitating form of communication impairment. Within clinical speech and languagetherapy “semantic therapy” is often carried out with these participants (RCSLT, 2005).However, for comprehension deficits, in the literature there is little systematic study ofthe content of semantic therapy or its efficacy. While there is a degree of consensusin the diagnosis of a semantic impairment for words (Whitworth et al., 2005), thereis less consensus in terms of what constitutes semantic therapy, how it works and theextent to which it generalises to untreated words.
SEMANTIC IMPAIRMENTS IN APHASIA
A distinction has been drawn between three kinds of impairment that might resultin difficulty in semantic tasks; modality specific “access” impairments (word meaningdeafness/blindness), lexical semantic impairments and a deficit affecting conceptualsemantics. The latter arises from models of language processing which differenti-ate between understanding of object concepts and lexical processing (Bierwisch &Schreuder, 1992). It is therefore important in assessing semantic processing to consideraccess to semantic information via a variety of modalities (picture only, via writtenword, via spoken word).
SEMANTIC THERAPIES FOR NAMING
While our focus in this paper is semantic therapy to improve comprehension, muchof the reported work about semantic therapy is actually focused on improving output;that is, naming (Nickels, 2002). The majority of semantic therapy studies for namingcan be categorised into three types. Facilitation therapy, which requires the personto carry out an activity matching the meaning to the word form (Howard, Hickin,Redmond, Clark, & Best, 2006), is generally used with output anomia, but has beenshown to have some effect with people with a semantic level deficit (Hickin, Best,Herbert, Howard, & Osbourne, 2002; Lorenz & Ziegler, 2009; Nickels & Best, 1996a,1996b).
Semantic Feature Analysis/Therapy (SFA/SFT) (Boyle, 2010) encourages the per-son to think about particular aspects of meaning of a word, using prompts (such as“group”, “use”, or “action”) to try and cue that word. Although the initial researchon SFA used this therapy for people with anomia and intact semantics (for a reviewsee Boyle, 2010), the therapy has now been validated for semantic level impairmentsof nouns and also for verbs using a similar therapy where agents and patients of thetreated verbs are elicited rather than features (Edmonds, Nadeau, & Kiran, 2009).
A third type of therapy is more explicitly targeted at semantic impairment and insome way tries to teach the meaning features which go with a particular word. A ther-apy for written naming described by Hillis (1998) explicitly taught similarities anddifferences between the meanings of semantically related words and was used withan individual with a severe central semantic impairment. Improvement was demon-strated in comprehension and spoken as well as written naming. Davis and Harrington(2006) used a therapy where the person selected from a choice the picture which wentwith a semantic feature description (e.g., “which one goes with milk”, with one ofpicture choices “cow”). They graded the difficulty of the task by making the pic-ture foils increasingly semantically related. As well as improvement in naming, theauthors describe an improvement to auditory comprehension such that the patientwas re-classified from Wernicke type to conduction aphasia.
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SEMANTIC THERAPIES FOR COMPREHENSION
Semantic therapies aimed at improving comprehension per se include categorisationtasks, word to picture matching, odd one out decisions, word picture verification, andmatching words to definition. In addition several therapies manipulate the degree ofsemantic relatedness in tasks. Scott (1987) reported treatment with a participant AB,where therapy involved semantic categorisation, word to picture matching, odd oneout judgements, and word picture verification, with increasingly related distractors.AB’s comprehension and his picture naming both improved following therapy, sug-gesting a single deficit. Behrmann and Lieberthal (1989) worked with CH, who theydemonstrated had a central semantic deficit. Therapy tasks included word–picturematching and matching words to definitions, focusing initially on superordinate infor-mation and then increasing the semantic relatedness of distractors. Behrmann andLieberthal demonstrated that CH showed improvement in categorisation. Grayson,Franklin, and Hilton (1997) worked with participant LR, with therapy involvingword–object and word–picture matching, categorisation and selection of written asso-ciates. Initially semantic distractor items in these tasks were unrelated to the targetitem, but later in treatment became semantically related to the target. LR’s perfor-mance improved on word to picture matching but not on control tasks unrelated totherapy, demonstrating that improvement was specific to therapy.
Bastiaanse, Nijboer, and Taconis (1993) reported a study with S, where compre-hension (spoken and written) was severely affected, as was naming. The participanttook part in a structured therapy programme using the semantic component of theirAuditory Language Comprehension Programme. This involved him (among othertasks) selecting from pictures when he heard a word, with increasing related dis-tractors. S’s performance on many language measures improved following therapy,suggesting that therapy was effective and that improvement generalised. However, it isworth noting that therapy did not only involve this specific task and that S was only2 months post onset.
Therapy studies for people with word comprehension impairments specific to theauditory modality are relatively rare. Most describe treatment for word sound deafnessand are based around minimal pair exercises and using lip reading (Hessler & Stadie,2006; Morris, Franklin, Ellis, Turner, & Bailey, 1996; Tessier, Weill-Chounlamountry,Michelot, & Pradat-Diehl, 2007). Francis, Riddoch, and Humphreys (2001) describetherapy for a person with word meaning deafness. They used reading word defini-tions and a synonym judgement task in a written form to access semantics, but foundthe therapy was more robust when the participant heard the word at the same timeas reading it, suggesting it was important to work on auditory processing as well assemantics. Similarly, in the Grayson et al. (1997) study where the participant had asemantic deficit AND an auditory processing deficit, semantic therapy only improvedwritten comprehension. It was only when an auditory processing therapy was addedto the semantic therapy that auditory comprehension improved.
DOES THE THERAPY GENERALISE TO UNTREATED WORDS?
Treatment for comprehension has been shown to generalise to production (Hillis,1998), as would be expected based on a model of a single semantic system commonto all modalities. However, does treatment on a particular set of words generalise tountreated words? The wealth of published facilitation studies (Nickels, 2002) providestrong evidence that effects are item specific; that is only the actual words which are
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treated improve. This lack of generalisation also seems to hold for individuals whohave a semantic deficit (Hickin et al., 2002; Nickels & Best, 1996a).
The issue of generalisation is less clear in the case of Semantic Feature Analysistherapy; while there is some evidence that the untreated words do improve (e.g., Boyle2004; Coelho, McHugh, & Boyle 2000), the improvement may be consistent with apractice effect derived from repeated testing (Nickels, 2002) and findings across stud-ies are not consistent. However, Stanczak, Waters, and Caplan (2006) found therapyeffects generalised for a person with lexical semantic impairment, but not for a caseof pure anomia. Rose and Douglas (2008) used a modified semantic feature therapyto compare verbal and gesture treatments for a central semantic deficit and foundthat there was no generalisation to a control category until it in turn was treated.Intriguingly, however, their participant did show improvement on a different namingtest and a semantic association test which could not be explained in terms of within-category improvements. The verb therapy in the Edmonds et al. (2009) study producednot only generalisation to closely related untrained verbs (e.g., weigh/measure) butalso some generalisation to unrelated words. Wambaugh and Ferguson (2007) treatedverb naming with a therapy more closely based on SFA and this did not show gen-eralisation, but this is probably because their participant had a lexical rather than asemantic impairment.
A slightly different therapy procedure, still based on meaning features wasdescribed by Kiran, Sandberg, and Sebastian (2011), comprising category generation,category sorting, feature generation, and yes/no feature questions. They contrastedtreatment of atypical and typical items, and demonstrated that generalisation hap-pened from atypical to typical members of the same category, but not in the otherdirection.
The Hillis and the Davis and Harrington studies described above provide furtherevidence that teaching meaning features more directly does generalise in the case of aclear semantic impairment. This generalisation appears to apply only to words whichare semantically related to the words worked on in therapy (Hillis).
HOW DOES SEMANTIC THERAPY WORK?
The effects produced in facilitation studies have appeared to work by priming the routebetween meaning and the word form (Hickin et al., 2002). The effect seems similar tothat of repetition priming in people without aphasia where the effect is long lastingand item specific (Wheeldon & Monsell, 1992). Facilitation, albeit testing accuracyrather than response latency, is also specific to the word treated and is long last-ing. Facilitation studies have also shown that the size of the treatment effect is notdependent on the depth of semantic processing required in the therapy task (Howardet al., 2006). Facilitation seems to depend on thinking of the meaning of the word andproducing that word.
Semantic feature analysis (SFA) therapy is often assumed to have its effect throughteaching meaning features but in fact the original authors of the SFA therapy stud-ies are quite clear that SFA constitutes a strategy to be used to cue words and hasbeen used with people with intact semantics but an output naming deficit (Boyle,2004, 2010; Coelho et al., 2000). Similarly the circumlocution-induced naming ther-apy described by Francis, Clark, and Humphreys (2002) showed generalisation, butthis was used with an output naming deficit and is also likely to be the employment ofa strategy.
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The Hillis (1998) paper describes a therapy which does specifically aim to teachmeaning features of words (for writing) and finds generalisation to untreated itemswithin the same categories. While the individual thus treated might have been expectedto be making good spontaneous recovery (being a young person with a head injury),the fact that written words in the untreated categories did not improve serves as acredible control. Hillis suggests that improvement following the meaning contraststherapy increased the specificity of the semantic representations for the trained items.This enrichment of semantic information generalised to words which had aspects ofmeaning in common with the treated items.
Studies which have looked at SFA for participants with semantic impairments havefound instances of generalisation. The clearest examples of this are in the case of gen-eralisation from atypical to less typical items. Irrespective of whether therapy is carriedout on typical or atypical category exemplars, meaning features are taught, so why thisdifference in effect? Kiran et al. (2011) consider atypical items to be more complex.In a replication Stanczak et al. (2006) show that the atypicality effect is found witha lexical semantic deficit, but not a post-semantic lexical deficit. They conclude thatpeople with semantic-level deficits “may benefit most when the variation is maximisedto reduce competition among items” (p. 380).
THE CURRENT STUDY
It has been shown (although in a limited number of studies) that semantic therapycan result in improved understanding. However, comprehension studies have not sys-tematically considered whether improvement is restricted to those items involved intherapy and have frequently involved a variety of therapeutic tasks. This study aimsto compare the performance of two participants with similar comprehension deficitsusing a single, highly specified semantic therapy task. The participants’ initial presen-tation will be discussed, content of therapy described and their response to therapydetailed. Where therapy is successful generalisation will be considered. Post-hoc anal-ysis will establish whether the degree of semantic relatedness between items affectsperformance.
PARTICIPANT DETAILS
Participant 1: AD
AD lived at home with a supportive wife. He tended to be dependent on her tofacilitate his communication. Background information is provided in Table 1. Wheninitially assessed, AD’s comprehension of everyday language showed difficulties withrapid topic shift and conversation which was not in context. His spontaneous outputwas easily understood, but with word finding difficulties evident. AD compensatedwell for his right-sided hemispatial neglect and this did not influence test results (seelater BORB results).
Participant 2: JAC
JAC also lived at home with his wife. Again, Table 1 provides further information. JAChad spoken language comprehension difficulties and his output was characterised bypredominantly English jargon with some neologisms. When asked, he was sometimes
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TABLE 1Participant details
AD JAC
Age at stroke 68 58Months post onset when seen 14 16Computerised Tomography
informationSlightly reduced attenuation in
left temporal & occipitalregions
Area of low density in leftanterior parietal region
Vision Right side neglect &hemianopia
Vision corrected with glasses(pre-stroke)
Mobility Unaffected UnaffectedEmployment Company director (retired) Teacher (retired)Age left education 16 Unknown, but extended
beyond 16
able to write single words which assisted in communicating his message, but he didnot do this spontaneously. JAC was not always aware of communication breakdown,and would continue to produce jargon output. His comprehension difficulties led toproblems with task explanation and transfer between tasks.
ASSESSMENT RESULTS
Word comprehension tests
Assessment focused on investigating the ability to access semantic informationfrom spoken, written, and pictorial input. Assessment involved word–picture match-ing, synonym judgement, picture verification, and judging semantic relationships.Wherever possible, spoken and written presentation modes were contrasted to allowfor comparison.
Both participants were assessed using the ADA word to picture matching tests(Franklin, Turner, & Ellis, 1992). Table 2 shows the results for AD and JAC. AD’sperformance on both versions was outside of the normal range, and modality did notinfluence performance. His errors were either to semantically related items, or to itemsboth semantically and phonologically related to the target. Similarly, JAC made errorson both versions of the task, falling just within the elderly control range on the audi-tory version. Again, all errors were to semantic or semantic and phonologically relateditems.
Tests of synonym judgement were also used. When AD was assessed on both theADA and Palpa (Kay, Lesser, & Coltheart, 1992) tests, a clear effect of modality ofpresentation was seen with performance on written items superior to auditory presen-tation (see Table 2). Imageability affected his performance on the Palpa (5 HI errors;13 LI errors; p = .03) but not ADA tests (6 HI errors, 8 LI errors). JAC had difficultieswith both types of presentation, with performance on both being outside of the nor-mal range. The apparent advantage of written presentation was non-significant. ForJAC, there was no effect of imageability on performance in either the PALPA or ADAtests.
A picture verification task was used to provide further information about theparticipants’ access to semantic information. Picture verification is a task described
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TABLE 2Initial assessment of comprehension (number correct)
by Howard and Franklin (1988) and used with their participant MK. The partic-ipant is shown a picture and then given a name that either matches the pictureor is a semantically or phonologically related foil word. AD’s performance wasimpaired on this task regardless of modality of presentation, although again theadvantage for written presentation was seen (McNemar; p = .016) (see Table 2).For the written version only two conditions were used (target and semantic foil)since the phonological foils would not always be orthographically related. It canbe seen that, with auditory presentation, AD’s performance was significantly worsegiven a semantically related name than one that was phonologically related tothe target. AD clearly had difficulty rejecting a name that bore a close semanticrelationship to the target word, and this was true for both auditory and writ-ten presentation. However, note that his performance for the targets and in thephonological conditions was also outside the normal range for elderly controlparticipants.
When JAC was tested on the same items (spoken presentation) he also had fargreater difficulty rejecting semantically related words than phonologically relatedwords (as for AD, performance on phonological foils was outside the normal range;in contrast, performance given the target was within normal range). JAC was alsotested with written presentation, where performance was significantly better thanspoken (McNemar; p < .001). However, he was still having difficulty with the task,tending to accept semantically related words as being the correct name for thepicture.
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Visual semantic tests
Both participants also completed the three-picture version of the Pyramids and PalmTrees test (Howard & Patterson, 1992) to examine access to semantics from pictorialinformation alone. Their results show that performance was impaired, even when nowords were present.
Given AD’s visual problems it was important to establish that his difficulties withsemantic tasks involving pictures were not accounted for by an object recognitionproblem. AD’s performance was within normal limits on tasks that involved matchingitems from different views or deciding whether drawings were of real objects (BORBminimal feature match 24/25, and object decision 27/32; hard items); (Riddoch &Humphreys, 1993). These tasks were not completed with JAC.
Auditory input tests
It is also important to investigate possible reasons for the apparent advantage of writ-ten over spoken presentation seen on some comprehension assessments. For bothparticipants, their performance on a range of tasks examining auditory/phonologicalprocessing was within normal limits (see Table 3). However, they both experiencedsome difficulty with longer minimal pairs and auditory lexical decision (in contrast togood performance on the written version). In conclusion, both AD and JAC appearedto have some auditory processing difficulties. This may account for the additional dif-ficulty auditory material presents but of course gives no account for their difficultieswith written presentation and with picture semantics.
Naming
A deficit in semantic processing has been established for comprehension, but thisshould also affect naming. On the Palpa frequency naming test, if self-correctionsare included as correct, AD scored 20/60 (11 of these self-corrected) and JAC 27/60(4 of these self-corrected). JAC showed no effect of frequency on performance. Hiserrors were mixed, with the predominant error perseverative in nature. He also made
ADA spoken lexical decision 160 147–160 (mean 155) 139 144ADA written lexical decision 160 154–160 (mean 159) 157 158Modality effect (in lexical
decision)?p < .01 p < .01
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Figure 1. JAC and AD: Comparison of performance across tasks (% correct).
a small number of semantic and phonological errors. JAC also did a written versionof the test, scoring 37/60. AD also showed no effect of frequency, with the predomi-nant error type being no response, with a small number of semantic errors. At times heattempted to produce some letter information, but this was not always correct. It canbe concluded that the difficulties with semantics contributed to these naming deficits.However, these results do not rule out additional output difficulties.
Summary of assessment findings
Both JAC and AD had difficulties accessing semantic information. This was notconfined to lexical semantics but appeared to extend to conceptual semantics (withJAC’s and AD’s performance both outside the normal range, although JAC’s perfor-mance was numerically superior to AD’s). Results demonstrated (at times) superiorperformance when written information was presented (for AD across two synonymjudgement tests and picture verification; for JAC only on picture verification). It ispossible that this could be explained by slight additional auditory processing deficits,although clearly other possibilities exist, which will be returned to in the discus-sion. Both participants had difficulties with spoken output. Assessment results acrossparticipants are summarised in Figure 1, to allow comparison.
THERAPY
Repeated measures
Although at the time of the study both participants were between 14 and 16 monthspost-onset, it remained important to make sure that any improvement seen followingtherapy could not be due to more general change occurring. Tests were repeated priorto therapy to establish whether performance fluctuated pre-therapy. Table 4 showsscores across tasks prior to therapy (spanning a 7-month period for AD and a 3-monthperiod for JAC). It can be seen that performance did not fluctuate significantly overthis time. The only exception is AD’s performance on the ADA auditory synonym
judgement test where his performance did improve between first and second assess-ment (McNemar; p = .002). However it should be noted that this was a gap of5 months. His performance tested a month later did not differ from the previousperformance (McNemar; p = .458).
Design of therapy
Therapy for AD and JAC focused on their ability to access the meanings of singlewords. While both participants did have some difficulty with phonological processing,they had much greater difficulty with semantic information, as demonstrated bothby assessment results but also by participant and carer report and observation. Theirsemantic difficulties became particularly evident in the verification task. This has dif-ferent demands than, for example, word to picture matching, where the participantis choosing between a small number of given items. This task format appeared to beparticularly sensitive and “reveal” the difficulties the participants were experiencing.For this reason the verification task was used within therapy. It had the added bene-fit that it did not require spoken output, therefore minimising demands on JAC andAD. Given that the evidence base provides few clear predictions, auditory presentationwas chosen as both individuals had goals to improve their comprehension of spokenlanguage. However, it involved processing of pictures too and the written word wasincluded as feedback.
A picture verification format was used, with the semantic foils chosen to be categoryco-ordinates of the pictured item, e.g., helicopter–aeroplane. There were equal num-bers of natural and artefact items. As discussed, the therapy literature does not providestrong predictions about generalisation of effects. The design of therapy thereforeincluded a comparison of treated and untreated items.
Many existing therapies for semantic comprehension difficulties are based onthe idea of working from large to fine semantic differences (see earlier discussion).Assessments such as the PALPA word–picture matching tests often assume semanticdifference will affect performance and build this into test design. However, currentsemantic naming therapies which demonstrate some generalisation to untreated itemsare based on fine differences between meanings of words. It was therefore decided torequire the participant to make fine-grade judgements in the picture verification task.
Both participants were tested using a set of 200 pictures (black and white line draw-ings) twice before therapy began, once with the correct name, once with a semantic foilname. These conditions were randomised across sessions. Table 5 shows their results
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TABLE 5Picture verification (200-item set; Number correct)
Old control data: Range(and mean) (N = 8) N AD JAC
on this assessment. It can be seen that both AD and JAC were impaired on this task,with both making many errors to semantic foil items. AD also made more errors thancontrol participants when given the target name.
The 200 items were then split into two groups (treated and untreated). Items wereassigned to group so that there were equal numbers of items which had been corrector incorrect and were balanced for frequency and overall category.
The same procedure was followed for AD and JAC. Using the 100-item treatmentset, the picture was shown and then a word (the target or semantically related name)was spoken, which they had to accept or reject. On the following session this wasreversed. Immediate verbal feedback was provided. If they were correct they were toldso and moved on. If incorrect, the two words (i.e., the correct and semantically relatedname) were written down for them to choose from, and the salient differences andsimilarities between the two items were discussed. Again they were given feedbackand if incorrect at this stage, the correct name was pointed out. AD and JAC wereseen at home on a twice weekly basis for between 9 (AD) and 12 (JAC) sessions. Thisvariation was due to what the individuals were able to tolerate. JAC was able to attendto short sessions of between 30 and 40 minutes and AD preferred longer sessions(60–90 minutes). However, they both had the same number of exposures to the itemsas in some sessions AD repeated the task. To examine what, if any, improvement hadoccurred as a result of therapy, both participants were re-tested on the full pictureverification task (i.e., treated and untreated sets recombined), presented once with thecorrect name and once with the semantic foil.
RESULTS BY PARTICIPANT
Participant JAC
JAC’s performance improved on the task, with his overall score significantly higher,as seen in Table 6. This overall improvement was primarily a result of improvedability to reject the semantic foil name, which was seen across both treated anduntreated items. While there was a slight decrease in ability to accept target name,given that performance overall improved, there was both a change in accuracy and ashift in criterion (i.e., a change in response bias). The pre and post therapy resultswere also examined using d-prime, and JAC shows both improved discrimination(d’ 1.730 and 1.940 respectively) and also a change in response bias (β = 0.173 and0.458 respectively).
Figure 2 shows JACs scores for the treated items across the therapy sessions,indicating a steady general improvement (on semantic foils).
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TABLE 6Assessments over time (JAC; Number correct)
Pyramids & Palm Trees (1 auditory; 2 written) 52 38 48 ( p = .06) 44 ( p = .180)Howard & Franklin picture verification
(written)194 167 167 –
ADA auditory synonyms 160 130 126 –ADA word reading 80 52 53 –
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Figure 2. JAC: Performance within therapy sessions.
While for JAC there was a significant effect of therapy across treated and untreateditems, it is important to examine what generalisation there was to other tasks. TheHoward and Franklin picture verification task is the test most closely related to ther-apy. However it should be noticed that this task differs in that JAC is being asked tomake phonological as well as semantic judgements. Surprisingly JAC showed no over-all improvement on this, being 79% correct before and after therapy. However, whenthis was examined further it was shown that, as for the actual therapy task, there wasa significant decrease in the number of errors where he accepted a semantically relatedword. The fact that there was no overall improvement on the task is an effect of anon-significant trend of increase in a different error category.
JAC also achieved a higher score on the auditory version of Pyramids and PalmTrees but this failed to reach significance. In contrast there was no change on written
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presentation of the picture verification task or auditory synonyms, but it should benoted that JAC performance was better on these tasks pre-therapy. Findings aretherefore mixed, but there was generalisation of improvement to untreated items andsome generalisation to different task formats. A task which was not expected to showany change, reading of single words, was also repeated and remained unchanged,confirming that the improvements were not due to some more general recovery.
Maintenance of improvement for JAC
Therapy clearly did produce significant improvement in JAC’s performance. To exam-ine whether these improvements were maintained over time, 4 months later JAC’sperformance was reassessed. As can be seen in Table 6, his score on the 200-item pic-ture verification test remained elevated overall, and for the semantic foils alone and, asbefore, this was irrespective of whether they had formed part of the treated group ornot. Performance on the Pyramids and Palm Trees test remained somewhat elevated,but was not significantly different from the pre-therapy score.
Participant AD
In contrast, for AD, following therapy, there was no significant improvement in hisperformance on the picture verification task, as can be seen in Table 7. There wasno improvement in his overall score, or in the distribution of his errors. Figure 3shows AD’s scores for the treated items across the therapy sessions, also indicatinga lack of consistent improvement across sessions. As for JAC, the pre and post ther-apy results were also examined using d-prime. AD shows similar discrimination values(d’ 1.03 and 0.97 respectively) and also a similar response bias (β = 0.57 and 0.61respectively). These findings show that he has not improved and both discriminabilityand response bias have not changed.
AD’s performance clearly did not improve, and no improvement was seen in theother related tasks. The only slight improvement was in naming, where he was ableto self-correct more items and made more semantic errors. The difference between
Figure 3. AD: Performance within therapy sessions.
the numbers correct is not significant, but when self-corrected items are included ascorrect, the difference does reach significance (see Table 7).
More detailed comparison of AD and JAC’s pre-therapy performance
Pre-therapy assessments indicated little difference between AD and JAC’s scores.However, they responded differently to the therapy. Are there any more qualita-tive differences between them? In the following section we examine performance onthe 200-item pre-test and on synonyms, to consider whether there are differences interms of store versus access deficits, performance on different categories, and whetherperformance is affected by any lexical or semantic variables.
JAC and AD’s performance was examined in terms of consistency of response ona repeated-measure (ADA synonym judgement). The data suggest both some consis-tency (to be expected, given that items not of equal difficulty) and a similar degree ofinconsistency between the two patients. It would not appear that there is an overallconsistency to their responses (AD: 14 items incorrect all three times, 22 items correctonce, 39 items correct twice, 85 items correct all three times; JAC 8 items incorrectall three times, 14 items correct once, 40 items correct twice, 98 items correct all threetimes).
There were equal numbers of natural and artefact items within the 200 pictures(although these were not balanced for frequency). The category of item did not affectJAC’s performance (40 artefact and 48 natural correct on foils; Chi square; p = .32).For AD performance did appear to be better for artefacts than natural items (58 and40 correct respectively on the semantic foil items; p = .016) on one administrationof this assessment. However, on two other administrations there was no significantdifference (36 artefact and 30 natural; p = .452, then 36 natural 40 artefact; Chi square;p = .662).
Within the picture verification test, items were chosen to be semantically related,by pairing category co-ordinates. However, with “semantically related” pairs the exactrelationship to the target can be difficult to quantify and largely subjective. While foilswere chosen as being category co-ordinates of the picture, of course some are more
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closely related to each other simply because of the nature of the category from whichthey are taken (for example, fruit is a more discrete category than furniture). If theimpairment is at a semantic level then one could hypothesise that pairs of words whichare more highly related should prove more challenging. In an attempt to examine this,post-hoc analyses were done on the participants’ scores before (and after) therapy inan attempt to relate their performance to a number of variables associated with thewords that could potentially affect their chance of success.
Ratings were collected for the names of the pictures and for the semantic foil names.Participants were asked to rate the individual words for how imageable they were andhow familiar they were with the item. Existing word frequency counts were used. Forthe pairs of items (target name and semantic foil word) participants were asked torate how semantically related they were and how visually similar the items were. Foreach set of ratings 20 young control participants (students) completed the ratings.The age range was 18–41, with a mean age of 24. Mean semantic relatedness ratingsfrom participants ranged from 2.30 to 6.00, on a 7-point scale, even though thesepairs of items had originally been chosen as being category co-ordinates of each other.In the ratings “dummy” pairs were also used which had little or no relation to eachother. These ratings were then used in analyses to examine which variables significantlypredicted performance on the task pre- and post-therapy (using logistic and multipleregression techniques). The variables used were semantic relatedness, visual similarity,word frequency, word familiarity and imageability.
OVERALL RESULTS
The majority of errors were where an incorrect semantic foil name was accepted as cor-rect, and it is these that will be considered. In simultaneous regression analyses with allthe above variables included, the degree to which the target and semantic foil pair hadbeen rated as being semantically related never predicted AD’s performance: Wald (1)= .298, p = .585 pre-therapy; Wald (1) = 1.66, p = .197 post-therapy. In contrast, forJAC the degree to which the items were rated as being semantically related predictedhis pre, immediate post, and 4 months post-therapy performance: Wald (1) = 23.31p < .001; Wald (1) = 3.98, p = .046, and Wald (1) = 9.36, p = .002 respectively. Thismeant JAC was more likely to get an item wrong if it had a higher semantic relatednessrating. This was not attributable to some kind of visual similarity between the items;the degree to which the two words were rated as being visually similar never predictedJAC’s performance (logistic regressions; Wald (1) = 1.598; p = .206; Wald (1) = .061;p = .805; and Wald (1) = .632; p = .427 respectively). AD and JAC’s performance istherefore qualitatively different with JAC showing a clear effect of semantic relatednesson his performance on this task.
DISCUSSION
The outcome of a highly specific form of semantic therapy, with two participantswith comprehension problems, reveals interesting differences. While both participantsappeared to have broadly similar assessment profiles both in terms of the type andseverity of their deficit, their response to an identical therapy differed.
For JAC reassessment revealed improvement on the therapy task, regardless ofwhether the items had been included in the set to be treated or not. Reassessment ofother tasks involving auditory semantic comprehension showed some generalisation
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to related tasks. The improvement was largely maintained, with slight deterioration,at 4-month follow-up. AD did not improve in response to therapy.
Although assessment profiles were similar for both participants, there were threepossible areas of difference prior to therapy which may have contributed to the out-come, though none of these potential differences was particularly well established.First, there were differences in the relationship between auditory and written wordcomprehension. For both participants there was some advantage of written presen-tation over auditory comprehension tasks. For JAC this was consistent, althoughperformance on tasks with written presentation was also impaired. For AD perfor-mance with written presentation was sometimes impaired but at other times waswithin the normal range, specifically in the synonym judgement tasks. For AD thissuperior performance on written synonyms compared with any other written taskcould be related to the fact that no pictures were present or that distractors in thistask are in fact unrelated (in contrast to, for example, word–picture matching whichhas semantically related distractors). However the latter explanation is unlikely giventhat semantic relatedness did not predict AD’s success in word picture verification.
The second possible difference is that AD could have a general conceptual/centralsemantic deficit, as oppose to a primarily lexical deficit for JAC. While just outside thenormal range on the Pyramids and Palm Trees test, JAC’s performance was somewhatbetter than that of AD (47/52 versus 40/52). Performance for JAC was predicted bysemantic relatedness (in contrast to AD’s performance).
The third possible way in which the two participants differed was in their spokenoutput. AD was able to produce social speech but this lacked content, reflected in hisscores on a confrontation naming task (9/60). In contrast while JAC produced jargon-type output he was able to name many more items in the same task (23/60). However,a stringent scoring system was used for naming, where only the first response wastaken. If self-corrections were counted, then the scores for the two patients becomesimilar (JAC 27/60; AD 20/60). In any case it is hard to see why this would explain adifference in therapy response for tasks which only worked on comprehension.
An explanation of JAC’s response to treatment will now be discussed, before con-sidering AD. JAC improved following therapy, on both treated and untreated itemsand on an auditory-written version of Pyramids and Palm Trees. How might thisimprovement be characterised? It is likely that JAC’s improved performance reflectsimproved access to semantic information from the auditory modality rather than animprovement in the semantic system itself. This modality specific effect is supportedby a lack of corresponding improvement on picture naming (written naming 39/60 vs31/60). Neither is there any improvement for written word–picture verification, despitethe fact that the written words were used in feedback. Although JAC is impaired atsemantic tests in all modalities, it is consistent with his assessment data that thereare additional problems when input is from the auditory modality. The difference inperformance between auditory and written versions of more challenging tests may bea reflection of the ephemeral nature of the auditory input, while the written formsof these assessments allow for repeated attempts at an item. This is unlikely to bethe whole explanation, however; impaired performance on auditory lexical decisionsuggests there is some additional auditory processing deficit. Also it should be notedthat the generalisation seen in the 200-item picture verification does not extend to theHoward and Franklin picture verification; this may well be because the test differs inthat phonological foils are also used.
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If there were an extra deficit in auditory comprehension, and it is this that wastreated, one might predict that improvement would be via improved mapping betweenlexical and semantic processing. Is this the auditory input equivalent of naming“facilitation” in output (Howard, Patterson, Franklin, Orchard-Lisle, & Morton,1985)? Francis et al. (2001) describe therapy for a person with word meaning deaf-ness, and this seems analogous to facilitation in that only the words treated improved,consistent with the notion that improvement is due to priming of the (lexical) seman-tic representation in association with its verbal representation. For JAC, however,untreated items show the same degree of improvement as treated items. JAC’s patternof improvement appears to be equivalent to naming therapies working more directlyon semantic processing which do show generalisation.
The treatment reported by Hillis (for discussion see Hillis, 1998), and used with herparticipant HG, is specifically aimed at working at the semantic level of processing.In Hillis’s therapy, HG was asked to name a picture. If a semantic error was pro-duced then this was drawn and the distinctions between target and error discussed.Following therapy her performance in written naming, spoken naming, word–pictureverification, repetition, and writing to dictation improved. There was generalisationto items which had not been treated but were in the same semantic categories as theuntreated items. Hillis argues that improvement was “at the semantic level itself –perhaps through increased specificity of semantic representations of trained items”(p. 654). The fact the trained item has “an enriched semantic representation” helpedHG discriminate it from other related items (and so, for example, made semantic errorsless likely for those items).
Hillis (1989) also described a participant who took part in orthographic therapyfor his naming difficulties (that is, orthographic cues given when he was unable toname). Despite this orthographic focus of therapy, both spoken and written nam-ing improved on treated items and untreated items from the same semantic category.As Nickels (2000) points out, this would suggest that therapy actually had an effecton the semantic system. She argues that the fact the participant reflected on his error(usually semantic) and the correct name, may have allowed him “to reflect on the dis-tinctions (in meaning) between his response and the target” (p. 113) and that this iswhat caused the therapy effect. Viewed in this way, the therapy has similarities withthat described in this paper but produced an effect across modalities.
As might have been predicted, post-hoc analysis showed that the degree to whicha semantic distractor was related to the target name predicted the likelihood of JAC’ssuccess on the therapy task over time. However, in stark contrast, this did not predictAD’s performance on the task. Therapy could be modified to utilise the finding thatsemantic relationship of items had a clear effect on performance for JAC. Therapycould have used “grading“ of the semantic distractors used. While this would givethe therapy structure and ensure a certain level of success for the participant, therapyworked for JAC with varied semantic contrasts; it may be that the presence of a seman-tic contrast is the important factor. Additionally, the results here suggest this wouldhave been of little relevance to AD as this did not appear to be a crucial factor affect-ing his performance. In discussing semantic relatedness, Nickels (2000, p. 109) suggeststhat “it is by no means certain, however, that this assumption of graded difficultyis valid for all aphasic people”. Horton and Byng (2002) also make the point thatsemantic relatedness could differ on an individual basis, related to experience andperception.
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Why did AD not benefit from the therapy? Could he have had a more generalcognitive impairment following his stroke which made it unlikely he would respondto direct therapy? This is unlikely; there were several examples of tests where hedemonstrated normal performance (written synonyms, written lexical decision, andpicture recognition). Additional evidence comes from performance at the 75th per-centile on Raven’s Coloured Progressive Matrices. Poor response to therapy could beexplained by a more serious auditory processing deficit than that of JAC; Graysonet al. (1997) describe a person with aphasia who had both semantic and auditory pro-cessing impairments. When they treated semantics alone auditory comprehension didnot improve; improvement only took place when a minimal pair training programmewas added to the semantic therapy. However, JAC and AD have a remarkably similarprofile in terms of the auditory processing tests, and both make errors on phonologicalas well as semantic foils in word/picture verification.
As suggested earlier it may be that AD’s deficit might be one of central semantics(whereas JAC may have a lexical semantic impairment), implicating picture process-ing as well as language. He did make more errors than JAC on the picture version ofthe Pyramids and Palm Trees Test, and performed within the normal range on writtensynonym judgements which do not require picture processing. Howard et al. (2006)found that once-off facilitation of naming had only a short-term effect for seman-tic impairments (the “semantic” group varied in their scores on Pyramids and PalmTrees). Stanczak et al. (2006), looking at naming treatment for typical and atypicalitems, found that their participant with a semantic deficit (but it should be noted heappeared to have a lexical semantic impairment) found typical exemplars of a cate-gory difficult to learn, and suggested that it was the many overlapping features in thewords which produced the difficulty. The therapy reported here was generally based onitems that were closely related semantically. In addition, a large number of items weretreated (and thus quite briefly treated), which is in contrast to most semantic therapiesin the literature. Thus for AD the related semantic distractors may have made the ther-apy confusing for him. In resolving the issue of AD’s lack of response to treatmentit would be instructive to compare therapy effects for individuals with more clearlydissociated lexical-semantic and central semantic deficits.
For JAC this highly structured specific therapy produced effects which gener-alised to other items and other tasks; this was not the case for AD. It can be seenthat this very specific form of semantic therapy produced correspondingly specificimprovement effects. The findings reinforce the claim by Nickels and Best (1996b) that“semantic therapy clearly cannot be considered a unitary treatment; slight changesin the nature of the task and its presentation may radically affect the effects of thetherapy” (p. 119).
Manuscript received 21 December 2011Manuscript accepted 1 June 2012
First published online 2 August 2012
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