Blogging about research: Functionally relevant items in the treatment of aphasia

Selecting the right words for therapyIt is possible to draw an analogy between interventions in speech therapy/pathology and interventions in pharmacology (i.e. drug-based interventions). Both interventions require a ‘substance’ and both interventions require a delivery method. In pharmacological interventions, the substance would naturally be the drug and the delivery method would be the syringe, canula, tablet etc, i.e. the method by which the drug is introduced to the body. As would be expected, in pharmacology, the effects of both the delivery mechanism and the substance need to be fully understood and researched before the intervention is rolled out for use with the general public. If you then extend this to the field of speech therapy/pathology and in particular interventions for people with aphasia that attempt to improve spoken word-retrieval abilities, you can similarly identify a substance and a delivery mechanism. However, in this area, research has had a strong focus on identifying the effectiveness of various delivery methods to the relative neglect of investigating the effects of the ‘substance’. In this analogy that I am making, the delivery mechanisms are the intervention tasks (e.g. phonological therapy, semantic therapy, semantic-phonological therapy, and the various ‘branded’ tasks that fall under these general banners, such as semantic feature analysis therapy and phonological components analysis therapy). The ‘substance’, in this analogy, represents the words/vocabulary that are used in order to exemplify the tasks, i.e. the words that the person with aphasia is practicing as part of therapy. Essentially, the lack of attention paid to the ‘substance’ in interventions for people with aphasia has left clinicians with little concrete guidance about how to go about selecting words to use within their interventions in order to increase the chances of positive outcomes.

The selection of stimuli in speech therapy/pathology interventions for people with aphasia, is something that I am interested in within a research capacity. This is something that should be obvious when I eventually get around to finishing off writing the manuscript describing the primary intervention study that formed a large component of my PhD research. I’m also currently in the process of conducting a systematic review of stimuli selection procedures for words in interventions for word-retrieval impairments as reported in the published research literature. Through this research I’ll eventually come to the conclusion that more attention needs to be paid to stimuli selection in order for interventions to test and inform cognitive-neuropsychological models of language processing, in other words to ensure that ‘therapy’ in upholding its side when it comes to the cycle of theory informing therapy and vice-versa.

So, this leads into this month’s blog about research which is a double-whammy with a joint review of:

Renvall, K., Nickels, L., & Davidson, B. (2013a). Functionally relevant items in the treatment of aphasia (part I): Challenges for current practice. Aphasiology, 27(6), 636-650, and:

Renvall, K., Nickels, L., & Davidson, B. (2013b). Functionally relevant items in the treatment of aphasia (part II): Further perspectives and specific tools. Aphasiology, 27(6), 651-677.

Review/Description

Together, these two articles present an interesting discussion on the issue of item selection in language-based therapies targeting improvements in word-retreival for people with aphasia. This is sparked by two important and inter-linked factors: i) the recurring finding that improvements in word-retreival following intervention (particularly impairment-based intervention) tend to be greatest, if not totally restricted to, words explicitly practiced within therapy (i.e. limited generalisation to other words when elicited within the same task conditions); and ii) the desire for words practiced in therapy to be meaningful and useful (i.e. functional) for the person with aphasia so that generalisation may be more likely to different contexts (i.e. so that words practiced in the clinic room may be more effectively used outside of the clinic room in the person’s day-to-day activities). However, Renvall et al (2013ab) argue that in reality, there is very little guidance as to how to actually go about the process of identifying and selecting ‘functionally relevant’ treatment stimuli: “the field lacks concrete tools, systematicity and transparency when attempting to identify functionally relevant items for treatment” (p645) – this is therefore a problem.

In first defining what is actually meant by the term ‘functionally relevant treatment items’, Renvall et al present two broad groups of items that may be considered to fall under this banner. The first group corresponds to those words that are ‘personally chosen’ by the person with aphasia (and possibly their family and with the support of the clinician). The second group relates to words that occur frequently in the language and may therefore be required frequently in everyday conversation. It should therefore be immediately obvious that these two groups are not necessarily mutually exclusive, as for a particular individual, words that are generally highly frequent in the language may overlap with those words that the person with aphasia may wish to improve.

Renvall et al then go one to discuss methods and tools that currently exist that may allow clinicians to identify both personally chosen words and also highly frequent words. In order to identify personally chosen words, the authors suggest that the person with aphasia may be encouraged to record some form of conversation diary so that popular topics of conversation can be systematically identified and this vocabulary items may be identified as an extension of this. A second method proposed is that of conversation analysis as this can provide a ‘window’ into people’s choices in conversational topics and also the words they tend to use. However, as the authors point out, words that may be functional to target in therapy may not be present in conversation samples for the reason that these words may be difficult for the person with aphasia to produce. In absence or other more formalised alternatives, a further suggestion is that the person with aphasia (and their family) is asked to compile a list of words they’d like to work on at that particular point in time (in acknowledgement that the nature of functional words may change throughout the recovery process_. However, this again has the potential drawback that the person with aphasia may not be able to effectively communicate those words that would be useful to work on as these are the words they currently have difficulty in producing. An adaptation of this is suggested to be where the clinician provides a ‘ready-made’ list and asks the person with aphasia to select words from this list. However, the authors state that while this frequently occurs, it is often up to the individual clinician to develop such lists using their own intuition, as again, there is an lack of such lists being published and validated.

Untitled

The top 20 words within the top 100 most frequent words based on Renvall et al (2013) analyses

The next discussion centres around methods for identifying generally frequent words. This includes discussion of various language corpora and databases that have been applied in previous research. Examples of this include the Kučera & Francis (1967) word counts and the CELEX database. The content and applications of these databases are described in some detail along with their limitations if applying these for both assessment and therapeutic purposes. The remainder of Part I then goes on to describe how the authors used lexical database (i.e. the CELEX database and the SUBTLEX-US, a database containing 51 million words extracted from American film and TV series in the 1990s and up to 2007))  in order to develop a list of the 100 most frequent words. Overall it was found that verbs are among the most frequent word class along with pronouns and adverbs. This is interesting in itself as a vast majority of published interventions targeting word-retrieval tend to focus on improving noun retrieval. Further analysis of these most frequent words also revealed that those words that were most frequent also tended less imageable and less concrete in comparison to words that were considered to represent ‘typical’ treatment stimuli (i.e. words in semantic categories such as body parts, fruits, vegetables, clothing, and so on). The implication of this being that further research should be carried out on interventions that aim to improve retrieval of abstract and low-imageable words as these characteristics appear to typify words that could potentially be most ‘functional’.

Part II continues the discussion of functionally relevant items for interventions in aphasia by discussing strategies for achieving similar goals in a related area, namely methods for selecting words incorporated into argumentative and alternative communication devices (AAC). Firstly, the distinction is drawn between what is considered, in the AAC literature, to be core vocabulary and fringe vocabulary. Core vocabulary refers to a relatively small set of vocabulary (200-250 words in total) that is consistent across individuals and consists of high-frequency words drawn from various word classes. The fringe vocabulary refers to words that are highly individualised and refer to words related to the individual’s ‘activities, interests, environment and personal style’. Renvall et al, naturally draw the comparison between their groups of frequently used words and personally chosen words as identified in Part I. However, they also point out that within the AAC literature, different researchers have tended to apply the term core vocabulary differently meaning that there is not necessarily and agreed upon definition, and hence selection method for identifying core vocabulary for AAC purposes (as is also comparable with the aphasia literature).

Frequent topics of conversation identified in previous research

Frequent topics of conversation identified in previous research

The article then goes on to discuss research that has sought to identify topics of conversation that are ‘typical’ and common for healthy speakers and speakers with aphasia on the grounds that knowing what people talk about can inform vocabulary selection. The article then presents further specific resources that may be helpful in informing vocabulary selection including a link to the authors’ project webpage that hosts some of the word lists previously discussed (http://www.ccd.edu.au/research/language/aphasia/functionallyrelevantitems/index.html).

Evaluation/Summary

It should be fairly clear that I’ve enjoyed reading these articles and further considering the issues they raise. Despite the fact the review is fairly substantial in size, it does feel to me as though I’ve really only scratched the surface in terms of what these articles raise. Therefore, in an attempt to wrap this post up reasonably efficiently, I’ll conclude by summarising what I see as the main reasons why speech therapists/pathologists, especially those working clinically with people with aphasia and acquired disorders of communication, should read these articles.

  1. It will raise awareness and encourage clinicians to reflect on what it means to them when they refer to intervention being ‘functional’
  2. It provides various suggestions on how clinicians may use structured principles and methods in order to guide selection of vocabulary in intervention
  3. It actually gives rich data in the form of tables, appendices, and web-hosted excel files filled with vocabulary lists and associated frequency data that can be used to inform vocabulary selection

As stated, at the beginning of this review, investigation of the ‘substance’ has been relatively neglected in the aphasia literature, and in language-based speech pathology in general. I for one will look forward to seeing more research and resources like this becoming available in the future.

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About chrissp1980
Currently a lecturer in speech pathology in North Queensland, Australia. I'm lecturing in acquired disorders of speech and language and also attempting to enthuse students in conducting clinically-relevant projects using principles of Evidence-Based Practice. Wish me luck!

One Response to Blogging about research: Functionally relevant items in the treatment of aphasia

  1. Pingback: Blogging about Research – August Edition | "Talks Just Fine"

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