IJLCD - Developing and piloting a functional numeracy assessment for people with aphasia

People with aphasia can have problems understanding or using numbers in everyday life - known as functional numeracy difficulties. However, testing this is hard because there are limited published assessments for functional numeracy difficulties for people with aphasia. 

This study aimed to explore, validate and pilot a wide-ranging, aphasia-friendly functional numeracy assessment to investigate how functional numeracy is impacted by aphasia severity and time pressure demands, and to explore predictors of PWA's functional numeracy.

The paper is:

Which blueberries are better value? The development and validation of the functional numeracy assessment for adults with aphasia' https://onlinelibrary.wiley.com/doi/full/10.1111/1460-6984.12867

Kerri Ichikowitz, Carolyn Bruce, Vanessa Meitanis, Kelly Cheung, Yekyung Kim, Esther Talbourdet, Caroline Newton

First published: 13 March 2023

This paper was awarded the IJLCD student prize.

Resources:
If you would like access to the online version of the Functional Numeracy Assessment, please contact the study authors.

The intervention study: Newton, C., Meitanis, V., Bruce, C., & Donlan, C. (2025). Evaluation of the SWAN game-based approach to re-building numeracy skills in aphasia: Feasibility and preliminary findings. https://doi.org/10.31234/osf.io/f7d39_v1

The survey of SLTs: Newton, C., Brancamp, D., & Brancamp, T. (2025). The rehabilitation of numerical processing and calculation in aphasia: An international survey of speech-language pathologists. https://doi.org/10.31234/osf.io/g63j9_v1

Please be aware that the views expressed are those of the guests and not the RCSLT.

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Transcript

Transcript Date: 

22 April 2025 

Speaker Key (delete/anonymise if not required): 

HOST:                         JACQUES STRAUSS 

KERRI:                        KERRI ICHIKOWITZ

CAROLINE:                CAROLINE NEWTON 

MUSIC PLAYS: 0:00:00-0:00:06 

HOST:                         0:00:06 Welcome to the RCSLT podcast. My name is Jacques Strauss. This is an IJLCD episode in which we talk to authors of papers published in the International Journal of Language and Communication Disorders. 

Today we are looking at a paper entitled, ‘Which blueberries are better value? The development and validation of the functional numeracy assessment for adults with aphasia’. We were joined by two of the authors, Kerri Ichikowitz and Caroline Newton, to talk about this paper and the assessment developed. I started by asking them to introduce themselves. 

KERRY:                      0:00:40 My name is Kerri Itchikowitz and I’m a speech and language therapist. I’m currently working as a research fellow at University College London and I’m going to be starting my PhD this September, actually, to continue the research that we’re talking about today. My PhD is going to be supervised by Caroline Newton, who you’ll hear a little bit more from in just a moment. 

CAROLINE:                0:01:03 I’m Caroline Newton and I’m an associate professor at University College London, otherwise known as UCL. My background is in linguistics. I’m a clinical linguist with a particular interest in aphasia and how aphasia impacts activities of daily life. 

HOST:                         0:01:22 Can you talk to us broadly about what clinical question you were trying to answer? 

CAROLINE:                0:01:28 This research relates to the difficulties with numbers and calculations that are experienced by some people who have aphasia. That might be, for example, a person who has difficulties with numbers and that means that they feel they lack confidence in dealing with money. And so, they’re going to the corner shop to buy a paper and to pay for the newspaper they hand over a £50 note and they rely on the person the other side of the counter to give them the correct change. Or another example might be, I remember speaking to a person had aphasia and, before their stroke, had taken the family out for dinner and been able quite easily to calculate the tip that he wanted to give to the people who’d been serving them in the restaurant. But since his stroke had been unable to do that and found that very frustrating. So, there are these difficulties with these real-world impacts. 

But despite this, these kinds of difficulties seem to be relatively rarely addressed clinically. [Inaudible 0:02:33] that we’re going to be talking about links to some broader research that we’ve been doing at UCL, some of which involves evaluating the feasibility of an intervention that was aimed to improve basic numerical skills in children with DLD and adults with aphasia. 

And as part of that study we included measures which linked very directly to the skills that we were training, but we also wanted to see if our intervention might have a positive impact on those numerical skills as applied in more functional activities. 

HOST:                         0:03:14 So, what does the literature say about numeracy and aphasia?

CAROLINE:                0:03:19 We know that some individuals recover spontaneously from numerical difficulties that they experience early after their stroke. For others with aphasia, numbers actually might be a relative strength compared to their linguistic difficulties, so they may have relatively well preserved mathematical skills even though they can’t process comparable rules in language. 

And then there’s this group in between those, for whom difficulties with numbers, with calculation, persist for much longer. The prevalence of those difficulties is unclear, but if you look across studies it’s possibly around 50% of people with aphasia show below typical performance on a range of numerical tasks. 

The range of difficulties that people experience might be actually as varied as their linguistic difficulties. So, some people may have problems with number concepts, so what is three? The fact that three is greater than two and less than eight. Other people may have difficulties with a count sequence, so counting from one to ten, which is for us something which has been automatic since we were very young. But for some people with aphasia that is an area of particular difficulty. Or they may start the count sequence and end it, but not fill in all the numbers between one and ten, so they might count one, three, eight, ten. 

For others, the count sequence might be a strength, so they might use that count sequence to access a number name. They can’t automatically produce the number eight, so they have to count up from one to get there. For others, they may have difficulty identifying the Arabic numeral, the digits, when they hear a number named. Other difficulties might be with calculations, so they might be simple calculations like simple arithmetic, simple addition, simple subtraction. We know that multiplication may be an area of particular difficulty for some people with aphasia. Difficulties with percentages. Fractions may be problematic. There’s a range of difficulties. 

Research also shows us that there may be a relationship between numerical difficulty and a person’s linguistic difficulty, so a person who has problems understanding language generally may include problems understanding number names. But that relationship, it seems, is not straightforward. There are measures of functional numeracy – that’s the core of this study. There are assessments of functional numeracy designed more broadly for clinical populations, but they maybe have language demands that perhaps then take into account the difficulties that people with aphasia may experience, and that may be a problem for accessing those assessments. 

There are functional assessments for people with aphasia, which include items related to number, but our feeling was that they lack the breadth required to assess aphasic individuals, their functional numeracy in a comprehensive way. So, this study aimed to fill that gap specifically and in terms of functional assessment. 

HOST:                         0:06:33 Just to restate what you were doing. It was really looking at how we can measure numeracy in people with aphasia, given that existing assessments may not be suitable because of the aphasia. And of course, we need these assessments to measure the level of impairment, we need to understand the impact it could have on a person’s life, and then, of course, to help us determine the efficacy of any interventions. 

CAROLINE:                0:06:57 That’s the aim, yes. And specifically, we wanted the questions, the items, to be setting numerical abilities in tasks that relate to everyday life activities, so that aren’t just doing classroom maths, if you like, but might be calculating… well, which blueberries are the best value, which is the name of the paper. 

HOST:                         0:07:18 So, Kerri, could you tell us a little bit more about how you undertook this research. 

KERRI:                        0:07:22 Yes, so this research was done as my Masters research project, and also just to add it was just after COVID, so everything was conducted online and designed specifically so that it could be all done remotely. 

This paper really describes our pilot validation study of this novel functional numeracy assessment that my co-authors and I developed, with the aim of assessing people with aphasia’s functional numeracy skills, really, and trying to address all of those things that Caroline’s touched on briefly. 

I think I’ll talk a little bit about the assessment itself and then move on to the design of the study. Our novel functional numeracy assessment has 23 questions. We developed these questions to assess a range of functional numeracy difficulties that people with aphasia report experiencing with everyday tasks, so looking at things like shopping, following recipes, telling the time, understanding sports scores, etc. – really trying to trying to focus on functional everyday activities. 

We specifically designed the assessment to be accessible for people with aphasia. As Caroline’s mentioned, this is something that we really feel that a lot of the existing assessments aren’t necessarily designed for people with aphasia, and we didn’t want people’s language difficulties to confound their performance on the assessment. 

We did this in a couple of ways. We limited the language demands as much as possible. We bolded keywords in written text. We had audio recordings of the questions, images to support understanding. We also had different response modes for different questions. This was done to try and mirror the responses we’d expect people would usually need to give in that type of functional scenario. We had some questions with multiple choice answers, spoken or typed responses. 

And now, to talk a little bit about the design of our study. We had a large group of people without aphasia, and then a smaller group of 20 people with aphasia who all completed the assessments online. The assessments included our novel functional numeracy assessment and then other existing validated numeracy assessments, which we had adapted to be more aphasia-friendly. This included a shortened version of the general health numeracy test, which measures objective numeracy in a way that we feel is really quite challenging, and we saw that in our in our results as well. And we also used the subjective numeracy scale, which is another existing, validated assessment which measures subjective numeracy. 

HOST:                         0:10:19 Just to clarify for listeners, the general health numeracy test checks how well someone can understand and use numbers in a health context. It includes tasks like reading charts, understanding risks, and doing basic calculations related to health information. The subjective numeracy scale is a questionnaire where people rate how good they think they are with numbers and how comfortable they feel using them. It doesn’t test actual skills, but measures confidence and preferences related to numerical information. 

Now, in your assessment, you created a time pressure task. Can you tell us a little more about this? 

KERRI:                        0:10:57 This was a novel task, and we created it, really, in an attempt to make an assessment that’s more ecologically valid, so something that replicates experiences people with aphasia might have in their everyday life when they’re needing to complete tasks requiring numbers and there are other pressures involved and increased processing demands and it’s not as straightforward as here’s a question and you’ve got all the time in the world to answer it. 

But we tried to get as kind of a bit closer to real life as we’re never really assessing people in their everyday life doing these tasks. So, the time pressure task, in that we require participants to complete a set of questions that were adapted from the full functional numeracy assessment, and they had a set amount of time to do these questions while there was a ticking clock counting down in the corner of the screen – really to try and mimic that pressure that can be experienced in everyday life. 

We’d heard stories of people finding they feel really, really pressured and their anxiety gets involved and it starts to cause even more difficulties. There’s some previous research that’s also been done looking at numeracy and aphasia and just some comments on the fact that people took really long to do tasks, and they could perform similarly to people without aphasia, so maybe they managed to do the numeracy task, but it just took them really long, and that could be something that really impacts them in their everyday life. 

The example we were already thinking about with the time pressure task is something like being in a busy supermarket aisle and you’re feeling pressured to make way for other people, you’re looking at the shelf, you’re trying to choose your groceries, trying to work out which blueberry is a better value – the title of our paper – and trying to do all these numeracy calculations and using your skills while you’re really pressured and there’s additional demands on your processing, and really, how can we assess that? 

HOST:                         0:13:06 Did the test work? What were your key findings? 

KERRI:                        0:13:12 We had three key findings, and the first finding is about the impact of aphasia on functional numeracy. We compared the group of people with aphasia to the group of people without aphasia, and we found that, yes, people with aphasia had significantly poorer functional numeracy compared to people without aphasia. 

We also found that our functional numeracy assessment was sensitive enough to pick up on functional numeracy difficulties that people with aphasia can have. 

Another interesting point here is that, as a group, people with aphasia did take significantly longer than the people without aphasia to complete the numeracy tasks. 

As well, some people with aphasia scored similarly to people without aphasia, which we’ve seen in previous research, but the people with aphasia took longer to complete the numeracy tasks. So, this is really suggesting that these people with aphasia would still be disadvantaged in everyday situations involving these tasks, even though they’re scoring okay on the assessments, they’re performing okay, but they’re just taking a lot longer. 

Our second key finding is about the reliability and validity of our functional numeracy assessment. We ran an analysis using the Kuder-Richardson formula to evaluate the internal consistency reliability of the assessment. We found that the assessment showed acceptable internal consistency reliability, which suggests that the questions in our assessment were reliably measuring what we want them to measure. 

And to evaluate concurrent validity, we compared performance on our functional numeracy assessment to the existing measure of objective numeracy that we used, which was the general health numeracy test, and we found a strong correlation between scores on our assessment and the general health numeracy test, which suggests that we had satisfactory concurrent validity. Really, what this means is it’s providing evidence that our new assessment is measuring the same underlying construct as this existing, validated numeracy assessment. 

The last key finding I want to talk about is the influence of time pressure on people with aphasia’s performance. Actually, in the end, what happened was our time pressure task did not seem to work as we expected. And contrary to what we predicted, people with aphasia’s scores did not differ across questions with and without time pressure. This is suggesting that the addition of time pressure didn’t have a significant effect on their performance, but we also think that perhaps the design of our novel task just did not induce sufficient feelings of pressure to mimic the experiences that people with aphasia might experience in everyday scenarios. We really think that this is something that would be interesting to do further research on, as we really need to find out what pressure is enough pressure. 

When we were designing this, it was a novel task; it was the first time that we’ve tried something like this and we really have to do some more work looking at what levels of pressure are the right amount of pressure. You don’t want to put people under so much pressure that they’re not even able to attempt the task. So, it’s tricky to replicate this in a research environment. 

Really, we think this will be interesting to look at in future, as if we were able to add time pressure to part of our functional numeracy assessment, this would increase the ecological validity of the assessment, which could give us a better picture of the difficulties people might experience in everyday life. 

CAROLINE:                0:17:05 It may be that it’s not just the time that’s problematic, it’s not just the speed that is problematic, it’s the speed in which I need to do these things with three people waiting behind me, and the social pressure of that in addition to the speed with which I can process this information. 

HOST:                         0:17:25 The countdown is perhaps not inducing the right kind of pressure, the social anxiety of inconveniencing other people, the anxiety of being seen to struggle, etc. To recap, we’ve again confirmed the difficulties people with aphasia have with numeracy, how number problems take more time for them to solve, and then there’s work to be done around mimicking those real life pressures in a research environment. 

I guess my next question is: what does all of this mean for SLTs who may not be involved in research?

CAROLINE:                0:18:02 I think numbers may seem quite niche to people who aren’t as deeply involved in this. It may seem like it’s not as big or as important an area as other areas of language, particularly where someone presents with quite serious aphasic difficulties. And I suppose it may seem quite niche especially for those of us for whom numbers are not problematic. 

Partly what we’ve tried to demonstrate in this conversation but also in the paper is that numbers are integral to so many important activities of daily life. So, I suppose a first message for therapists would be ask about numbers. As I’ve mentioned earlier, numbers aren’t routinely assessed as how we work with people with aphasia. Working with numbers may be important to them because they’ve lost something that they were able to do before their stroke. And think about everyday circumstances in which number problems may arise. So, I guess, first, ask about numbers. 

I guess, secondly, consider ways of circumventing the difficulties. So, there currently aren’t a lot of evidence-based assessments or interventions. We hope this is a valuable start in terms of identifying where problems might arise for individuals. And actually, subsequent to this work, I was involved in some work where we were asking clinicians who had spotted these numeracy difficulties what they did in terms of intervention. And what we found was, actually in terms of assessment, people were being creative in devising informal assessments, and they were created to in intervention, so devising bespoke interventions that worked for the individuals and [inaudible 0:19:46] numeracy difficulties. 

So, SLTs might need to be creative. This could this could be considering the strategies that a person with aphasia might use. For example, I mentioned earlier the person who counts from one to get to the number. So, if it’s difficult to access a number name, consider counting up from one to get there, or using your fingers to count up to a number if that helps get to the correct name for the number. Or a person with aphasia asking others to write important times and dates in their diary or, increasingly, into our phones. 

Speaking of phones, our phones now come with voice recognition, they come with text-to-speech tools. There’s a calculator handy on every phone I’ve ever I’ve ever had, and these might be really useful tools. 

But there may also be other gadgets and devices out there. I’m thinking of gadgets and devices that have been designed for people who live with sight loss. The Royal National Institute for the Blind have a range of products like talking kitchen scales, talking watches, phones with talking digits, which may be useful. These kinds of things that may help circumvent the difficulties that people experience and that may have this real-world impact. 

A third thought was just to ensure that other professionals are aware of these difficulties where that’s relevant, and how those difficulties might impact everyday tasks. For example, if you are working with a client who has problems working with clocks and reading a clock, or managing a budget, then it may be useful to involve an occupational therapist in managing that person’s difficulties. Or if you have a person whose difficulties with numbers then affects their ability to deal with or manage medication, so thinking of dosage and dose frequency, well, that’s something that their GP needs to know about so they can effectively manage their health. 

And then, I guess, a fourth thing in terms of what therapists could be doing is watch this space, in a way, and look out for future work from us at UCL, from other places who are seeking to fill the gap in terms of assessment, in terms of intervention. 

HOST:                         0:22:05 Of course, if there’s anyone listening to the podcast who has thoughts on interventions that they found helpful, please do get in touch, we’d love to hear from you. 

So, Kerri, what research should we be doing next? 

KERRI:                        0:22:18 I think a really big message here is that we really need further research in this area. We really need to build the evidence base of both assessments and interventions that are accessible for people with aphasia, can be used in clinical practice. And these studies need larger groups of people with aphasia to validate numeracy assessments and trial these interventions, so that these studies have sufficient power and we can be more certain about the results of the studies. 

We think that our functional numeracy assessment that we’ve spoken about today, we think that the development’s heading in the right direction. It’s definitely still in its infancy and there’s a lot we want to do to improve the assessment, but as Caroline said, definitely watch this space. I’m going to be starting my PhD in September, and this is something I’m really looking forward to doing some more work on, hopefully refining our assessment, starting to build the evidence base, and then also working on an intervention to help people with aphasia regain these numeracy skills. 

HOST:                         0:23:27 Any limitations that we should take into consideration? 

KERRI:                        0:23:31 Yes, so one limitation of our study, really, we feel, comes from the design of our assessment itself. We think that it could be helpful for this assessment to be more systematic in how its assessing different numeracy skills. We’ve attempted to cover different potential areas of difficulty that have been reported that Caroline’s spoken about already, like transcoding, number comparison, counting, etc. But we think that these skills could be assessed more systematically by having more items that are tapping each skill. This would just help us get a better picture of someone’s specific difficulties and where the breakdown may occur. 

However, that being said, it is difficult to do this and keep the assessment a reasonable length. At the moment, it takes an average about 20 minutes with 23 questions in the assessment as it is at the moment. But we really need to find the balance between having a manageable number of questions and then also the systematic assessment of different skills.

We also had limited power in many of our analyses as we had a relatively small group of 20 people with aphasia. This prevented more in-depth analyses of performance across different skills and possible predictors of numeracy abilities. And we really need greater power in in these kinds of analyses and studies so we can be more sure of our results. 

HOST:                         0:25:08 Finally, are there any take-home messages? 

CAROLINE:                0:25:10 It’s a small community, so we’d love to hear from people, researchers, or clinicians who are interested in in this area, so that we can connect. It’s always been great for me to talk to clinicians who are working with these kinds of difficulties. 

KERRI:                        0:25:27 Think about numbers. Ask about numbers. We know that number difficulties can be really important to people with aphasia. It can bother them that they can’t do the things they used to do. There’s some research which talks about number difficulties leading to reduced independence, reduced participation in everyday life. All of these things are really important to people with aphasia. 

HOST:                         0:25:51 A very big thank you to Kerri and Caroline for their time. As always, please do see the show notes for links to the article and other resources that may be of interest. If you have thoughts on this area, let us know, and we can put you in touch with our guests. 

Every now and then, we do ask that you rate and review the podcast and share it with your colleagues so that we can continue to promote research and advocate for SLTs and service users in the UK and beyond. 

Until next time, keep well. 

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