Overview

Dyscalculia is a learning disorder that refers to difficulties learning mathematics and arithmetics.¹ Two main types of dyscalculia are distinguished based on the way of presenting the information, namely verbal dyscalculia which refers to difficulties understanding the mathematical concepts and information given verbally, and lexical dyscalculia, which involves trouble understanding the mathematics given in writing. Four more types of the disorder are distinguished based on the type of learning difficulty, namely practognostic, graphical, operational, and ideognostical dyscalculia.²

What is dyscalculia?

Dyscalculia is a learning difficulty that involves trouble understanding mathematical concepts and, in some cases, information that is presented as numbers. The first symptoms of the disorder usually appear in childhood as difficulties understanding basic mathematical concepts and performing mathematical operations, such as additions and substractions. It results from abnormalities in the brain area that handles numerical skills. Dyscalculia is not related to the intelligence of the person, it is a disorder that solely affects a person’s mathematical and number-related skills. It is estimated that around 6% of people across the world might have dyscalculia; however, there might be many more people affected by the disorder without knowing it.^1,3,4

Types of dyscalculia

Determining the type of dyscalculia a child develops might help the parents or caregivers to better understand their child’s disability, manage the symptoms, and provide them with the necessary help to overcome the impediment and learn effectively. It is important to know that for each of the types of dyscalculia, it is possible to find a way of presenting the information that will cause less trouble to the child and will be easier to comprehend and understand.

Based on how the information or a mathematical concept is presented, two types of the disorder are distinguished:

• Verbal dyscalculia – Individuals with this disorder struggle to grasp mathematical concepts when explained verbally. They usually do not find it problematic when the information is given in writing. A person with verbal dyscalculia can write and read numbers but they are not able to talk about them or understand the same information given verbally. They most often also struggle to remember the names of the mathematical concepts and ideas.
• Lexical dyscalculia – Essentially, the reverse of verbal dyscalculia. A person with lexical dyscalculia understands the mathematical concept when given verbally but struggles with the same information presented in writing. They have trouble reading mathematical symbols and numbers as well as mathematical equations. Therefore, they can handle a mathematical equation read for them but find it difficult if they have to read the equation by themselves.

The other four types of dyscalculia are distinguished according to the type of learning difficulty the person experiences:

• Practognostic dyscalculia – This type of dyscalculia involves issuestranslating mathematical concepts into information that can be used in real life. In other words, a person with prognostic dyscalculia experiences trouble understanding what type of information the mathematical concept gives them. For example, a person with practognostic dyscalculia cannot differentiate between quantity and values, for instance to determine which object is larger, heavier, or more expensive. Simple tests that canbe used to determine whether a person has this type of dyscalculia involve comparing numbers and asking questions about them, as presented below (Figure 1).

3 7

Which number is greater?

3 ₇

Which number is taller?

Figure 1. Examples of simple tests that may cause problems for a person with practognostic dyscalculia.

• Graphical dyscalculia – This involves difficulties in the writing and understanding of mathematical symbols. A person with this type of disorder understands mathematical concepts and can process the information given verbally but struggle to use the symbols and formulae which are very often applied when the mathematical concept is presented in writing. Therefore, it might be classified as a subtype of lexical dyscalculia. A simple test to determine whether a person has graphical dyscalculia might involve solving a simple mathematical operation, for instance, 4+9=? When this equation is given in writing it causes troubles since it includes symbols. However, if it is read for the person, it simplifies the problem.
• Operational dyscalculia – People with this form of dyscalculia struggle to perform mathematical operations and calculations. They understand numbers and the relationship between them but find it difficult to manipulate numbers and symbols to solve the mathematical problem. They can determine which number is bigger or smaller but performing mathematical operations on them, such as addition, subtraction, multiplication, division, and more complex operations, causes trouble. It can be simply determined by asking a person to perform simple mathematical operations.
• Ideognostical dyscalculia – This type of disorder involves difficulties understanding and remembering mathematical concepts. A person with ideognostical dyscalculia has trouble with the conceptual understanding of mathematics rather than performing mathematical operations. They struggle to grasp mathematical concepts and principles, as well as relationships between numbers. For instance, they may find it difficult to understand the reason behind the rule of order of operations. A person with ideognostical dyscalculia might also experience trouble carrying out mathematical operations without using numbers. They understand the ‘how’ of mathematics but struggle with the ‘why’ behind it. Simple questions the answers to which might reveal ideognostical dyscalculia, require explaining the mathematical concepts and the reason for using them, for instance, ‘What does division represent?’^2,5

The simple tests and questions included in the description of each of the types of dyscalculia cannot be used for diagnostic purposes. They are given only to help to understand the differences between different categories of the disorder. Only a healthcare provider can diagnose this condition following a comprehensive evaluation.

How to determine the type of dyscalculia?

The teachers and parents or caregivers are most likely to notice the first symptoms of dyscalculia, which usually involve difficulties with basic mathematical concepts and operations on numbers that are presented to the child at school. If such problems are noticed, it might be useful to contact the child’s healthcare provider or directly a pediatrician who might have broader knowledge about this type of disorder.

To diagnose dyscalculia, the child’s maths-related skills will be tested; however, to confirm that the difficulties are caused by dyscalculia, other possible causes such as hearing or vision problems, or mental health-related conditions must be eliminated. The healthcare provider will recommend appropriate tests and examinations. Once the diagnosis is confirmed, the specific type of dyscalculia must be identified. It is usually done through a dedicated set of tests that consist of simple mathematical problems and exercises that involve numbers and mathematical symbols. The result depends on the correctness of the test but also on the time required to give the answer. The person carrying out the evaluation will determine the type of dyscalculia depending on the types of exercises the child experiences difficulties with. 

Early diagnosis is very important and gives hope for effective treatment since the child’s brain is still developing. The parents or caregivers will be provided with a comprehensive explanation of the child’s condition and ways of managing the impediments. They will be advised on the choice of the learning methods the most appropriate for the child and their individual case.¹

Summary

Dyscalculia is a learning impediment that involves difficulties understanding the information given in numbers and consequently results in troubles with understanding mathematical concepts and performing mathematical operations. These issues may be related to how the information is presented. Some people find it difficult to understand written mathematics but find it easier when the same information is given verbally (lexical dyscalculia) whereas others have an opposite problem (verbal dyscalculia). Four other types of dyscalculia can bedistinguished, namely:

• practognostic dyscalculia which involves trouble translating mathematical concepts into information useful in real life;
• graphical dyscalculia which leads to difficulties in reading and comprehending mathematical symbols (such as +, -, x, =);
• operational dyscalculia which results in the inability to perform mathematical operations (for instance addition, subtraction, and multiplication);
• ideognostical dyscalculia which involves problems understanding the mathematical concepts and principles.

Determining the type of dyscalculia is very important for the successful management of the symptoms and helps to find a learning method effective for each individual patient.