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Neurodiversity and how it relates to psychometric testing

26 March 2024

Making assessments accessible to neurodiverse populations

By Andrea Swanepoel

This post highlights some factors you should consider to ensure that your psychometric assessments are as accessible as possible to neurodiverse populations, using dyslexia as an example. According to estimated prevalence rates, dyslexia appears to be the most diagnosed neurodiverse condition, both globally and locally.     

Neurodiversity refers to the natural variation in human cognitive functioning and that there is no single ‘right way’ for the brain to operate (Doyle, 2020). It generally includes neurodevelopmental conditions such as Autism Spectrum Disorder (ASD), Attention Deficit/Hyperactivity Disorder (ADHD/ADD), Dysgraphia, Developmental Coordination Disorder (DCD), Dyscalculia, and Tourette Syndrome (Thompson & Miller, 2018).  

Due to their neurobiological wiring, neurodiverse people differ in how they think, learn, process information, and interact with the world around them. Each neurodiverse person experiences their condition differently. Generally, each neurodiverse condition brings with it its own set of strengths and weaknesses but should never be seen as a disability.     

The neurodiversity movement is changing the narrative from focusing on deficits to understanding how various brains work differently, and then fostering a more inclusive and understanding environment.    

It is estimated that between 15-20% of the world’s population has some kind of neurodiverse condition (Doyle, 2020). Therefore, there is a strong possibility that individuals within a pool of job applicants at any given time are neuroatypical. Because of this, in as much as it is possible, it should be ensured that the selection process, including the administration of psychometric tests, does not discriminate unfairly against this cohort.  

In the table below both the local and global estimated prevalence rates of neurodiverse conditions are described.  

Neurodiverse Condition  

Prevalence Rate in SA  

Global Prevalence Rate  

ADHD: characterised by a persistent pattern of inattention and/or hyperactivity-impulsivity that has a direct negative impact on academic, occupational, or social functioning (WHO, 2022).  

Between 2.5 and 4.3% of adults (Schoeman & de Klerk, 2017) 

Approximately 2.5% of the population 

ASD:  is a diverse group of conditions, characterised by some degree of difficulty with social interaction and communication. Other characteristics are atypical patterns of activities and behaviours (WHO, 2023).  

1-2% of the population (Autism South Africa) 

1% of the population (De Goede, 2022) 

Dyslexia: is a specific learning disability that is neurobiological in origin. It is characterised by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities (IDA).  

Between 3 to 7% of the population; however, up to 20% may have some degree of symptoms (DiSA)  

1 in 10 people (Zauderer, 2023)  

DCD: also known as dyspraxia affects movement and co-ordination as well as fine motor skills, such as writing or using small objects (NHS, 2020).  

Affecting around 5 to 6% (Pedro & Goldschmidt, 2019). 

Fluctuates between 1.8 and 8% (Biotteau et al., 2020)  

Dyscalculia: is a specific and persistent difficulty in understanding numbers which can lead to a diverse range of difficulties with mathematics (Sharma, 2022).  

Between 6 and 8% of school children (Du Plessis, 2022)  

Between 3 and 7% (Haberstroh, 2019) 

Dysgraphia: is the condition of impaired letter writing by hand, that is, disabled handwriting. Impaired handwriting can interfere with learning to spell words in writing and speed of writing text (IDA).  

Estimation could not be found  

5 to 20% (Cleveland Clinic) 

Tourette Syndrome: The main symptoms of TS are tics. A person can have tics ranging from simple, temporary tics lasting a few weeks or months, to having many complex tics that are long-lasting (CDC)  

Estimate of prevalence could not be found  

Around 0.3 to 0.7% (Schaich et al., 2020)  

It is thought that dyslexia is the most widely diagnosed neurodiverse condition, which may mean that there is more likely than not someone with dyslexia in a talent pool at any given time.  It is important for us to understand the challenges faced by dyslexic individuals, the impact dyslexia can have on psychometric assessments, and the accommodations we can offer to mitigate the effect of the symptoms.   

Defining Dyslexia: It’s much more complex than you thought 

Dyslexia is defined as a hereditary learning difficulty that primarily affects areas in the brain that process language in the forms of reading, writing, and spelling. The core challenge is identifying speech sounds (phonics) and learning how they relate to letters and words (decoding) which effectively leads to reading (DiSA).  

Dyslexia is seen to exist on a spectrum with various classifications (DiSA). Symptoms can vary greatly between individuals, even within the same category.  

Some of the different categories of dyslexia are:   

  • Phonological Dyslexia: Difficulty with connecting sounds to letters (decoding) and manipulating sounds in words.  

  • Surface Dyslexia: Challenges with recognising whole words by sight, often relying on sounding them out.  

  • Rapid Naming Deficit: Difficulty quickly naming letters, numbers, or objects, impacting reading fluency.  

  • Double Deficit Dyslexia: Combines difficulties in both phonological and rapid naming skills.  

  • Other classifications: Include visual dyslexia (reversing letters), spatial dyslexia (trouble with layout and direction), and auditory dyslexia (struggle to process spoken language).  

It is important to remember that the conditions mentioned under the neurodiversity umbrella above are often comorbid. Research (McGrath, et al., 2019) shows that up to 40% of people who have dyslexia may also have ADHD, 30% of people with dyslexia have dysgraphia (Ashraf, 2020), and 26% have dyscalculia.   

Notwithstanding the above, dyslexic symptoms also co-occur with the following: 

  • Speech and language disorders which can make it challenging to learn new vocabulary and develop strong reading comprehension skills.  

  • Executive functioning disorders which affect cognitive skills such as planning, organisation, time management, and self-control.  

  • Anxiety and depression which can be more common in individuals with dyslexia due to the challenges they face in school and social situations. 

It's critically important to understand that dyslexia is not related to intelligence.  (DiSA). Individuals with dyslexia can possess strong cognitive abilities and excel in areas not assessed by traditional psychometric tests. Some of these pronounced strengths are 3D visual thinking, verbal skills, and long-term memory (Genius within).   

How do the symptoms of dyslexia influence test administration?  

Assessments most often used in the selection space are designed to assess cognitive ability, personality traits, and/or specific skills, and rely heavily on written language and sometimes timed tasks, all areas where dyslexic individuals might face challenges. We need to think carefully to ensure that what we are measuring and the test batteries we choose are job relevant.  

More specific ways in which dyslexia can affect the test administration process are described below:   

  • Slow and effortful decoding can significantly impact reading comprehension.   

  • Extended time is required to read questions and answer choices, which may lead to time pressure and potential errors.   

  • Written responses may not be clear or accurate. This might disadvantage them in tests requiring written responses.  

  • Fine motor difficulties associated with dyslexia can make writing slower and more laborious, adding further stress and time pressure.  

  • Timed tests place pressure on dyslexic individuals who may already struggle with decoding and processing information quickly. This can lead to rushed answers and inaccurate results.  

  • Remembering test instructions is challenging, especially complex sequences, or having to remember multiple pieces of written information simultaneously.  

  • Dyslexia can potentially hinder vocabulary development, making it harder to understand complex test language and technical terms. This can disadvantage them in tests with verbal reasoning or specific knowledge assessments.  

  • The pressure of standardised testing can exacerbate dyslexia-related challenges, leading to anxiety and stress, which can further hinder performance.  

  • Online tests with limited accessibility features or hard copy tests with small font sizes or poor contrast can further complicate difficulties.  

Symptoms associated with the comorbid conditions are not mentioned above. These add another layer of complexity to the test administration process.   

Looking at the above, it is obvious that difficulty with written language can present significant hurdles when taking psychometric tests. By understanding the challenges, we can offer appropriate accommodations to individuals with dyslexia.   

Accommodations during psychometric testing 

Before the assessment process begins, it is important for the test administrator to know if the test taker has been diagnosed with dyslexia, or any other neurodiverse condition in order to discuss and offer appropriate accommodations during the assessments.  A possibility could be to include a question related to neurodiversity on the consent form, simultaneously offering accommodation, to encourage disclosure. It should be explicitly stated on the consent form that the neurodiverse condition will not be disclosed to a third party without the written consent of the test taker. Not every neurodiverse individual might want to disclose their condition in fear of the disclosure negatively affecting their chances at being employed.   

According to the APA, during the assessment, accommodations offered may include the following:  

  • Quiet and distraction-free environment: Minimising external distractions can improve focus and concentration during the assessment. Also offer noise cancelling earphones.   

  • Extended time: Additional time can alleviate pressure and allow the individual to process information and complete tasks at their own pace.  

  • Reader/scribe: A trained reader can read test questions aloud, and a scribe can write answers dictated by the individual. This eliminates the reading barrier and focuses on their cognitive abilities.    

  • Alternative test formats: Depending on the assessment, alternative formats like audio recordings or enlarged print can be offered.  

  • Breaks: Allowing short breaks at regular intervals can help maintain focus and reduce fatigue.  

  • Assistive technology: Use of specific text to speech software to transcribe speech into text, like TalkType, Dragon NaturallySpeaking, and Google's speech-to-text technology or spell-check can be allowed to minimise the impact of dyslexia on reading and writing tasks.  

  • Dyslexia-friendly fonts: Opt for clear and easy-to-read fonts like OpenDyslexic which is a typeface designed against some common symptoms of dyslexia such as letter-spacing, font-weight, and font-family. It aims to improve readability for dyslexic readers.   

  • Colour filters or overlays: Reduce visual strain and improve reading comfort.  

If possible, a post-assessment review of the assessment results with the individual, considering the impact of dyslexia on specific tasks can provide more accurate insights into their overall abilities.  

In general, accommodations do not influence the ability/skill/knowledge measured, however, it is up to the professional to ensure that the accommodation type does not negatively influence the measurement of job relevant constructs. Not all accommodations will be suitable for every individual or every assessment. Collaboration and open communication are key to ensuring a fair and accurate assessment experience for people with dyslexia.   

The benefits of employing someone with dyslexia  

The Sir Richard Branson’s of the world are often game-changers and may disrupt industries. They provide solutions that we didn’t know we needed and solve problems we didn’t know we had (Griggs, 2020). Additional benefits in including people with dyslexia in your workforce could include (Hennessey, 2023): 

  • Their excellent visual and spatial reasoning, which can be valuable in roles, such as engineering, design, and architecture. They may find it easy to visualise complex concepts and identifying patterns.  

  • Their unique approach to information processing causes them to be highly creative problem solvers. They may think "outside the box" and come up with innovative solutions that others might miss.  

  • Their strong sense of determination and resilience. They may be highly motivated to succeed and possess a strong work ethic.  

  • Their strong verbal communication and interpersonal skills, due to their experience overcoming challenges in these areas.  

  • Their highly empathetic and understanding nature due to their own experiences with facing difficulties.  


One in five people worldwide may have symptoms of dyslexia (Zauderer, 2023).  This prevalence rate means that there is a good chance that a person with dyslexia is part of any talent pool at any given time. As psychology professionals it is our responsibility to understand the effect of the symptoms on the test administration process and the accommodations we can offer to minimise the effects thereof to ensure, as much as we can, a fair selection process. 



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