High-Intensity Aphasia Therapy Is Cost-Effective in People With Poststroke Aphasia: Evidence From the COMPARE Trial.

BACKGROUND: Evidence from systematic reviews confirms that speech and language interventions for people with aphasia during the chronic phase after stroke (>6 months) improve word retrieval, functional communication, and communication-related quality of life. However, there is limited evidence of their cost-effectiveness. We aimed to estimate the cost per quality-adjusted life year gained from 2 speech and language therapies compared with usual care in people with aphasia during the chronic phase (median, 2.9 years) after stroke. METHODS: A 3-arm, randomized controlled trial compared constraint-induced aphasia therapy plus (CIAT-Plus) and multimodality aphasia therapy (M-MAT) with usual care in 216 people with chronic aphasia. Participants were administered a standardized questionnaire before intervention and at 12 weeks after the 2-week intervention/control period to ascertain health service utilization, employment changes, and informal caregiver burden. Unit prices from Australian sources were used to estimate costs in 2020. Quality-adjusted life years were estimated using responses to the EuroQol-5 Dimension-3 Level questionnaire. To test uncertainty around the differences in costs and outcomes between groups, bootstrapping was used with the cohorts resampled 1000 times. RESULTS: Overall 201/216 participants were included (mean age, 63 years, 29% moderate or severe aphasia, 61 usual care, 70 CIAT-Plus, 70 M-MAT). There were no statistically significant differences in mean total costs ($13 797 usual care, $17 478 CIAT-Plus, $11 113 M-MAT) and quality-adjusted life years (0.19 usual care, 0.20 CIAT-Plus, 0.20 M-MAT) between groups. In bootstrapped analysis of CIAT-Plus, 21.5% of iterations were likely to result in better outcomes and be cost saving (dominant) compared with usual care. In contrast, 72.4% of iterations were more favorable for M-MAT than usual care. CONCLUSIONS: We observed that both treatments, but especially M-MAT, may result in better outcomes at an acceptable additional cost, or potentially with cost savings. These findings are relevant in advocating for the use of these therapies for chronic aphasia after stroke.

High-Intensity Aphasia Intervention Is Minimally Fatiguing in Chronic Aphasia: An Analysis of Participant Self-Ratings From a Large Randomized Controlled Trial.

BACKGROUND: High-intensity therapy is recommended in current treatment guidelines for chronic poststroke aphasia. Yet, little is known about fatigue levels induced by treatment, which could interfere with rehabilitation outcomes. We analyzed fatigue experienced by people with chronic aphasia (>6 months) during high-dose interventions at 2 intensities. METHODS: A retrospective observational analysis was conducted on self-rated fatigue levels of people with chronic aphasia (N=173) collected during a previously published large randomized controlled trial of 2 treatments: constraint-induced aphasia therapy plus and multi-modality aphasia therapy. Interventions were administered at a higher intensity (30 hours over 2 weeks) or lower intensity (30 hours over 5 weeks). Participants rated their fatigue on an 11-point scale before and after each day of therapy. Data were analyzed using Bayesian ordinal multilevel models. Specifically, we considered changes in self-rated participant fatigue across a therapy day and over the intervention period. RESULTS: Data from 144 participants was analyzed. Participants were English speakers from Australia or New Zealand (mean age, 62 [range, 18-88] years) with 102 men and 42 women. Most had mild (n=115) or moderate (n=52) poststroke aphasia. Median ratings of the level of fatigue by people with aphasia were low (1 on a 0-10-point scale) at the beginning of the day. Ratings increased slightly (+1.0) each day after intervention, with marginally lower increases in the lower intensity schedule. There was no evidence of accumulating fatigue over the 2- or 5-week interventions. CONCLUSIONS: Findings suggest that intensive intervention was not associated with large increases in fatigue for people with chronic aphasia enrolled in the COMPARE trial (Constraint-Induced or Multimodality Personalised Aphasia Rehabilitation). Fatigue did not change across the course of the intervention. This study provides evidence that intensive treatment was minimally fatiguing for stroke survivors with chronic aphasia, suggesting that fatigue is not a barrier to high-intensity treatment.

Why is a flamingo named as pelican and asparagus as celery? Understanding the relationship between targets and errors in a speeded picture naming task.

Speakers sometimes make word production errors, such as mistakenly saying pelican instead of flamingo. This study explored which properties of an error influence the likelihood of its selection over the target word. Analysing real-word errors in speeded picture naming, we investigated whether, relative to the target, naming errors were more typical representatives of the semantic category, were associated with more semantic features, and/or were semantically more closely related to the target than its near semantic neighbours were on average. Results indicated that naming errors tended to be more typical category representatives and possess more semantic features than the targets. Moreover, while not being the closest semantic neighbours, errors were largely near semantic neighbours of the targets. These findings suggest that typicality, number of semantic features, and semantic similarity govern activation levels in the production system, and we discuss possible mechanisms underlying these effects in the context of word production theories.

Naming in a multilingual context: Norms for the ICMR-Manipal colour picture corpus in Kannada from the Indian context.

There have been many published picture corpora. However, more than half of the world's population speaks more than one language and, as language and culture are intertwined, some of the items from a picture corpus designed for a given language in a particular culture may not fit another culture (with the same or different language). There is also an awareness that language research can gain from the study of bi-/multilingual individuals who are immersed in multilingual contexts that foster inter-language interactions. Consequently, we developed a relatively large corpus of pictures (663 nouns, 96 verbs) and collected normative data from multilingual speakers of Kannada (a southern Indian language) on two picture-related measures (name agreement, image agreement) and three word-related measures (familiarity, subjective frequency, age of acquisition), and report objective visual complexity and syllable count of the words. Naming labels were classified into words from the target language (i.e., Kannada), cognates (borrowed from/shared with another language), translation equivalents, and elaborations. The picture corpus had > 85% mean concept agreement with multiple acceptable names (1-7 naming labels) for each concept. The mean percentage name agreement for the modal name was > 70%, with H-statistics of 0.89 for nouns and 0.52 for verbs. We also analyse the variability of responses highlighting the influence of bi-/multilingualism on (picture) naming. The picture corpus is freely accessible to researchers and clinicians. It may be used for future standardization with other languages of similar cultural contexts, and relevant items can be used in languages from different cultures, following suitable standardization.

Examining Dose Frameworks to Improve Aphasia Rehabilitation Research.

The effect of treatment dose on recovery of post-stroke aphasia is not well understood. Inconsistent conceptualization, measurement, and reporting of the multiple dimensions of dose hinders efforts to evaluate dose-response relations in aphasia rehabilitation research. We review the state of dose conceptualization in aphasia rehabilitation and compare the applicability of 3 existing dose frameworks to aphasia rehabilitation research-the Frequency, Intensity, Time, and Type (FITT) principle, the Cumulative Intervention Intensity (CII) framework, and the Multidimensional Dose Articulation Framework (MDAF). The MDAF specifies dose in greater detail than the CII framework and the FITT principle. On this basis, we selected the MDAF to be applied to 3 diverse examples of aphasia rehabilitation research. We next critically examined applicability of the MDAF to aphasia rehabilitation research and identified the next steps needed to systematically conceptualize, measure, and report the multiple dimensions of dose, which together can progress understanding of the effect of treatment dose on outcomes for people with aphasia after stroke. Further consideration is required to enable application of this framework to aphasia interventions that focus on participation, personal, and environmental interventions and to understand how the construct of episode difficulty applies across therapeutic activities used in aphasia interventions.

No negative impact of word retraining on vocabulary use or clarity of communication in semantic dementia.

Word retraining techniques can improve picture naming of treated items in people with semantic dementia (SD). The utility of this, however, has been questioned given the propensity for under- and overgeneralization errors in naming in SD. Few studies have investigated the occurrence of such errors. This study examined whether, following tailored word retraining: (1) misuse of words increases, (2) the type of naming errors changes, and/or (3) clarity of communication is reduced. Performance on trained and untrained word naming from nine participants with SD who completed a word retraining programme were analysed. Responses from baseline and post-intervention assessments were coded for misuse (i.e., trained word produced for another target item), error type, and communication clarity. All participants showed significant improvement for trained vocabulary. There was no significant increase in misuse of words, with such errors occurring rarely. At a group level, there was an increased tendency toward omission errors for untrained items, and a reduction in semantically related responses. However, this did not impact on clarity scores with no consistent change across participants. In sum, we found no negative impacts following tailored word retraining, providing further evidence of the benefit of these programmes for individuals with SD.

Results of the COMPARE trial of Constraint-induced or Multimodality Aphasia Therapy compared with usual care in chronic post-stroke aphasia.

BACKGROUND: While meta-analyses confirm treatment for chronic post-stroke aphasia is effective, a lack of comparative evidence for different interventions limits prescription accuracy. We investigated whether Constraint-Induced Aphasia Therapy Plus (CIAT-plus) and/or Multimodality Aphasia Therapy (M-MAT) provided greater therapeutic benefit compared with usual community care and were differentially effective according to baseline aphasia severity. METHODS: We conducted a three-arm, multicentre, parallel group, open-label, blinded endpoint, phase III, randomised-controlled trial. We stratified eligible participants by baseline aphasia on the Western Aphasia Battery-Revised Aphasia Quotient (WAB-R-AQ). Groups of three participants were randomly assigned (1:1:1) to 30 hours of CIAT-Plus or M-MAT or to usual care (UC). Primary outcome was change in aphasia severity (WAB-R-AQ) from baseline to therapy completion analysed in the intention-to-treat population. Secondary outcomes included word retrieval, connected speech, functional communication, multimodal communication, quality of life and costs. RESULTS: We analysed 201 participants (70 in CIAT-Plus, 70 in M-MAT and 61 in UC). Aphasia severity was not significantly different between groups at postintervention: 1.05 points (95% CI -0.78 to 2.88; p=0.36) UC group vs CIAT-Plus; 1.06 points (95% CI -0.78 to 2.89; p=0.36) UC group vs M-MAT; 0.004 points (95% CI -1.76 to 1.77; p=1.00) CIAT-Plus vs M-MAT. Word retrieval, functional communication and communication-related quality of life were significantly improved following CIAT-Plus and M-MAT. Word retrieval benefits were maintained at 12-week follow-up. CONCLUSIONS: CIAT-Plus and M-MAT were effective for word retrieval, functional communication, and quality of life, while UC was not. Future studies should explore predictive characteristics of responders and impacts of maintenance doses. TRIAL REGISTRATION NUMBER: ACTRN 2615000618550.

Investigating the influence of semantic factors on word retrieval: Reservations, results and recommendations.

There is consensus that word retrieval starts with activation of semantic representations. However, in adults without language impairment, relatively little attention has been paid to the effects of the semantic attributes of to-be-retrieved words. This paper, therefore, addresses the question of which item-inherent semantic factors influence word retrieval. Specifically, it reviews the literature on a selection of these factors: imageability, concreteness, number of semantic features, typicality, intercorrelational density, featural distinctiveness, concept distinctiveness, animacy, semantic neighbourhood density, semantic similarity, operativity, valence, and arousal. It highlights several methodological challenges in this field, and has a focus on the insights from studies with people with aphasia where the effects of these variables are more prevalent. The paper concludes that further research simultaneously examining the effects of different semantic factors that are likely to affect lexical co-activation, and the interaction of these variables, would be fruitful, as would suitably scaled computational modelling of these effects in unimpaired language processing and in language impairment. Such research would enable the refinement of theories of semantic processing and word production, and potentially have implications for diagnosis and treatment of semantic and lexical impairments.

Exploring the effects of verb and noun treatment on verb phrase production in primary progressive aphasia: A series of single case experimental design studies.

Evidence of generalization to connected speech following lexical retrieval treatment in Primary Progressive Aphasia (PPA) is scarce. Consequently, this study systematically investigated changes in verb phrase production following lexical retrieval treatment in a series of single case experimental design studies. Four individuals with PPA (three semantic- and one logopenic variant PPA) who had previously demonstrated that they could integrate verbs and nouns into sentence structures in a cueing paradigm, undertook a sequence of verb and noun lexical retrieval treatments using Repetition and Reading in the Presence of a Picture. Production of treated nouns- and/or verbs-in-isolation significantly improved following treatment for three of the four participants. Verb phrase production did not improve for one of these participants (logopenic PPA), perhaps due to the relatively small treatment dose. Two participants (semantic variant PPA) did, however, demonstrate across-level generalization, with improvement in treated verbs and using those verbs in (untreated) verb phrases. Their verb phrase production improved most after lexical retrieval treatment for both nouns and verbs, suggesting this combined approach may benefit across-level generalization for some individuals in clinical practice.

Serial position effects in graphemic buffer impairment: An insight into components of orthographic working memory.

This study investigated the nature of graphemic buffer functioning and impairment, through analysis of the spelling impairment shown by GEC, a man with acquired dysgraphia and clear characteristics of graphemic buffer impairment. We discuss GEC's error patterns in relation to different processes of orthographic working memory. This is the first study to show the contribution of these processes in one individual through performance on different spelling tasks. GEC's spelling errors in writing to dictation showed a linear serial position effect, including deletions of final letters. These "fragment errors" can be explained as the result of information rapidly decaying from the buffer (reduced temporal stability). However, in tasks that reduced working memory demands, GEC showed a different error distribution that may indicate impairment to a different buffer process (reduced representational distinctiveness). We argue that different error patterns can be a reflection of subcomponents of orthographic working memory that can be impaired separately.

Outcomes of semantic feature analysis treatment for aphasia with and without apraxia of speech.

BACKGROUND: To date, studies have not explored whether a dual diagnosis of aphasia plus apraxia of speech (AOS) versus aphasia alone (APH) affects the response to language-based naming treatments. AIMS: To compare the effects of semantic feature analysis (SFA) treatment for individuals with APH versus aphasia plus AOS, and to test if the presence of AOS impacted the effects of treatment. METHODS AND PROCEDURES: A non-randomized experimental group study was conducted to explore the treatment, generalization and maintenance effects between the AOS and APH groups. Participants included nine individuals with aphasia and 11 with concomitant aphasia and AOS. Dependent measures included lexical accuracy, number of sound-level distortions, and lexical stress and syllable segmentation errors. OUTCOMES AND RESULTS: Both groups showed significantly improved naming accuracy of trained items for up to 2 months post-treatment. Improvement on naming accuracy of untrained items post-treatment, both semantically related and unrelated to trained items, was lower in magnitude. That this may have been due to effects of repeated probing (which included target repetition) or regression to the mean cannot be excluded. There was a tendency for the AOS group to respond slightly better to treatment than the APH group overall, which was not correlated with aphasia severity. Also, measures of phonetic accuracy and fluency improved for both groups, with no main effect of group. Treatment effects did not generalize to formal measures of (untrained) picture naming or expression of correct information units in discourse in a story retelling task. CONCLUSIONS AND IMPLICATIONS: Findings indicate that individuals with aphasia plus AOS can gain equivalent benefits in word retrieval and production from the language-based SFA treatment as individuals with aphasia alone. This may be, in part, due to the tendency for SFA to incorporate principles of practice that are known to support motor learning in AOS, such as high intensity, random stimulus presentation and variable practice. Findings provide further support for high-intensity practice and use of self-generated features to facilitate maintenance of effects. What this paper adds What is already known on the subject SFA treatment is the most common intervention for word-finding difficulties for individuals with aphasia. AOS is a common concomitant disorder to aphasia. However, it is not clear whether the effects of language-based SFA treatment are mitigated by the presence of AOS, which tends to respond well to treatments focused on articulatory-kinematic aspects of speech movement. What this paper adds to the existing knowledge This study compares the effects of SFA in a group of individuals with aphasia alone and a group with similar severity of aphasia but with concomitant AOS, ranging from mild to moderate-severe. Overall, AOS did not have a negative effect on response to the treatment. What are the potential or actual clinical implications of this work? Individuals with aphasia plus AOS can be expected to benefit to a similar degree from SFA as people with aphasia alone. It is likely that the use of practice principles of high intensity, random stimulus presentation and varied practice are important components of the protocol.

An Exploration of the Impact of Group Treatment for Aphasia on Connected Speech.

OBJECTIVE: Group treatment enables people with aphasia to practise communication skills outside the typical clinician-patient dyad. While there is evidence that this treatment format can improve participation in everyday communication, there is little evidence it impacts linguistic abilities. This project aimed to investigate the effects of 'typical' group treatment on the communication skills of people with aphasia with a focus on word retrieval in discourse. METHODS: Three people with aphasia took part in a 6-week group therapy programme. Each week focused on a different topic, and three topics also received a home programme targeting word retrieval. The six treated topics were compared with two control topics, with regard to language production in connected speech. Semistructured interviews were collected twice prior to treatment and twice following the treatment and analysed using (a) word counts; (b) the profile of word errors and retrieval in speech; (c) a measure of propositional idea density, and (d) perceptual discourse ratings. RESULTS: Two participants showed no significant improvements; one participant showed significant improvement on discourse ratings. CONCLUSIONS: This study provides limited support for group treatment, leading to improved communication as measured by semistructured interviews, even when supplemented with a home programme. We suggest that either group treatment, as implemented here, was not an effective approach for improving communication for our participants and/or that outcome measurement was limited by difficulty assessing changes in connected speech.

Too harts, won sole: Using dysgraphia treatment to address homophone representation.

Previous spoken homophone treatment in aphasia found generalization to untreated homophones and interpreted this as evidence for shared phonological word form representations. Previous written treatment of non-homophones has attributed generalization to orthographic neighbours of treated items to feedback from graphemes to similarly spelled orthographic word forms. This feedback mechanism offers an alternative explanation for generalization found in treatment of spoken homophones. The aim of this study was to investigate the mechanism underpinning generalization (if any) from treatment of written homophones. To investigate this question a participant with acquired dysgraphia and impaired access to orthographic output representations undertook written spelling treatment. Generalization to untreated items with varying degrees of orthographic overlap was investigated. Three experimental sets included homographs (e.g., bank-bank), heterographs (e.g., sail-sale), and direct orthographic neighbours (e.g., bath-path). Treatment improved written picture naming of treated items. Generalization was limited to direct neighbours. Further investigation of generalization found that items with a greater number of close neighbours in the treated set showed greater generalization. This suggests that feedback from graphemes to orthographic word forms is the driving force of generalization. The lack of homograph generalization suggests homographs do not share a representation in the orthographic lexicon.

Treatment for spoken and written word retrieval in the semantic variant of primary progressive aphasia.

This study investigated whether a treatment programme for spoken word retrieval, supplemented with written naming, was beneficial for an individual with right-hemisphere dominant semantic variant of PPA (svPPA). Assessment and treatment were delivered remotely through Skype. Treatment consisted of two phases of lexical retrieval therapy (Repetition and Reading in the Presence of a Picture: RRIPP), with and without written responses (Phases 1 and 2 respectively), and a third treatment phase based on the procedures of Conceptual Enrichment (COEN) therapy. The first two phases of treatment resulted in short-lasting improvements in spoken and written word retrieval, with greater improvement in Phase 2 when written production was also required. Both treatment phases resulted in gains only for treated items, but generalised to different depictions to those treated. However, Phase 2 also resulted in significant improvement of treated items on a comprehension task. COEN treatment did not result in significant gains in word retrieval or comprehension. This study reinforces the value of a simple lexical retrieval treatment delivered remotely. It adds to the current evidence that anomia in svPPA can be responsive to treatment, but also shows that challenges remain regarding maintenance effects and the generalisation of treatment effects to connected speech.

Developmental graphemic buffer dysgraphia in English: A single case study.

A single case study is reported of a 10-year-old, English-speaking boy, L.S., who presented with spelling errors similar to those described in acquired graphemic buffer dysgraphia (GBD). We used this case to evaluate the appropriateness of applying adult cognitive models to the investigation of developmental cognitive disorders. The dual-route model of spelling guided this investigation. L.S. primarily made "letter errors" (deletions, additions, substitutions, transpositions, or a combination of these errors) on words and nonwords and in all input (aural and visual) and output modalities (writing, typing, oral spelling); there was also some evidence of a length effect and U-shaped serial position curve. An effect of lexical variables on spelling performance was also found. We conclude that the most parsimonious account is an impairment at the level of the graphemic buffer and without systematic cognitive neuropsychological investigation, the nature of L.S.'s spelling difficulty would likely have been missed.

The Single-Case Reporting Guideline In BEhavioural Interventions (SCRIBE) 2016 Statement.

We developed a reporting guideline to provide authors with guidance about what should be reported when writing a paper for publication in a scientific journal using a particular type of research design: the single-case experimental design. This report describes the methods used to develop the Single-Case Reporting guideline In BEhavioural interventions (SCRIBE) 2016. As a result of 2 online surveys and a 2-day meeting of experts, the SCRIBE 2016 checklist was developed, which is a set of 26 items that authors need to address when writing about single-case research. This article complements the more detailed SCRIBE 2016 Explanation and Elaboration article (Tate et al., 2016 ) that provides a rationale for each of the items and examples of adequate reporting from the literature. Both these resources will assist authors to prepare reports of single-case research with clarity, completeness, accuracy, and transparency. They will also provide journal reviewers and editors with a practical checklist against which such reports may be critically evaluated. We recommend that the SCRIBE 2016 is used by authors preparing manuscripts describing single-case research for publication, as well as journal reviewers and editors who are evaluating such manuscripts. SCIENTIFIC ABSTRACT Reporting guidelines, such as the Consolidated Standards of Reporting Trials (CONSORT) Statement, improve the reporting of research in the medical literature (Turner et al., 2012 ). Many such guidelines exist and the CONSORT Extension to Nonpharmacological Trials (Boutron et al., 2008 ) provides suitable guidance for reporting between-groups intervention studies in the behavioural sciences. The CONSORT Extension for N-of-1 Trials (CENT 2015) was developed for multiple crossover trials with single individuals in the medical sciences (Shamseer et al., 2015 ; Vohra et al., 2015 ), but there is no reporting guideline in the CONSORT tradition for single-case research used in the behavioural sciences. We developed the Single-Case Reporting guideline In BEhavioural interventions (SCRIBE) 2016 to meet this need. This Statement article describes the methodology of the development of the SCRIBE 2016, along with the outcome of 2 Delphi surveys and a consensus meeting of experts. We present the resulting 26-item SCRIBE 2016 checklist. The article complements the more detailed SCRIBE 2016 Explanation and Elaboration article (Tate et al., 2016 ) that provides a rationale for each of the items and examples of adequate reporting from the literature. Both these resources will assist authors to prepare reports of single-case research with clarity, completeness, accuracy, and transparency. They will also provide journal reviewers and editors with a practical checklist against which such reports may be critically evaluated.

The Single-Case Reporting Guideline In BEhavioural Interventions (SCRIBE) 2016 Statement.

Reporting guidelines, such as the Consolidated Standards of Reporting Trials (CONSORT) Statement, improve the reporting of research in the medical literature (Turner et al., 2012). Many such guidelines exist, and the CONSORT Extension to Nonpharmacological Trials (Boutron et al., 2008) provides suitable guidance for reporting between-groups intervention studies in the behavioral sciences. The CONSORT Extension for N-of-1 Trials (CENT 2015) was developed for multiple crossover trials with single individuals in the medical sciences (Shamseer et al., 2015; Vohra et al., 2015), but there is no reporting guideline in the CONSORT tradition for single-case research used in the behavioral sciences. We developed the Single-Case Reporting guideline In Behavioral interventions (SCRIBE) 2016 to meet this need. This Statement article describes the methodology of the development of the SCRIBE 2016, along with the outcome of 2 Delphi surveys and a consensus meeting of experts. We present the resulting 26-item SCRIBE 2016 checklist. The article complements the more detailed SCRIBE 2016 Explanation and Elaboration article (Tate et al., 2016) that provides a rationale for each of the items and examples of adequate reporting from the literature. Both these resources will assist authors to prepare reports of single-case research with clarity, completeness, accuracy, and transparency. They will also provide journal reviewers and editors with a practical checklist against which such reports may be critically evaluated.

Nonlinear spelling in graphemic buffer deficit.

In this paper, we describe a case of nonlinear spelling and its implications for theories of the graphemic buffer. C.T.J., an individual with an acquired deficit of the graphemic buffer, often wrote the letters of his responses in a nonlinear temporal order when writing to dictation. The spatial ordering of the letters was maintained: Letters in the later positions of the words were written towards the right side of the response, even when written before letters in earlier positions. This unusual phenomenon has been briefly reported in three prior cases but this study provides the most detailed analysis of the phenomenon to date. We specifically contend that the decoupling of the temporal and spatial aspects of spelling is difficult to reconcile with competitive queuing accounts of the graphemic buffer.

Challenges in the use of treatment to investigate cognition.

The use of data from people with cognitive impairments to inform theories of cognition is an established methodology, particularly in the field of cognitive neuropsychology. However, it is less well known that studies that aim to improve cognitive functioning using treatment can also inform our understanding of cognition. This paper discusses a range of challenges that researchers face when testing theories of cognition and particularly when using treatment as a tool for doing so. It highlights the strengths of treatment methodology for testing causal relations and additionally discusses how generalization of treatment effects can shed light on the nature of cognitive representations and processes. These points are illustrated using examples from the Special Issue of Cognitive Neuropsychology entitled Treatment as a tool for investigating cognition.

Orthographic learning in developmental surface and phonological dyslexia.

Phonological decoding skill has been proposed to be key to successful sight word learning (orthographic learning). However, little is known about how children with phonological dyslexia, who have impaired phonological decoding, acquire sight words, or why children with surface dyslexia can have normal phonological decoding skill yet impaired sight word acquisition. This study addressed this issue by investigating orthographic learning in two 10-year-old children: S.D., with a reading profile of surface dyslexia, and P.D., with a reading profile of phonological dyslexia. They participated in two experiments exploring the role of phonological decoding and paired-associate learning in orthographic learning. The results showed that, first, P.D.'s orthographic learning ability was better than S.D.'s, despite her phonological decoding skills being poorer. Second, S.D. showed impaired paired-associate learning abilities while P.D. did not. Overall, the results indicate that phonological decoding ability does not translate directly to orthographic learning ability, and that paired-associate learning ability may also be associated with success in orthographic learning.