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Chapter 4

Fill in the information you have

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#Dyscalculia and working memory  

Dyscalculics have different patterns of working and visual memory.

Working memory means holding information in your head for when you need it.

Examples of working memory are remembering phone numbers and birthdays or recalling an address or location.

Visual memory is recalling something seen previously, for example, a reference or verification number.

You can help by filling in the information you already have and avoiding asking people to remember numbers, like reference and verification numbers.

Show the number throughout the journey. If it’s online, show the number on each screen, especially if your service is a complex journey over many screens.

Make sure people know where to find reference numbers if it's on paper.

Reference numbers confirm an action or act as a key. Some people get stressed about reference numbers and obsess about keeping track of them. Give context about reference numbers so people know why they need them.

Tell people:

  • what the reference number is

  • if they need to keep the number safe

  • when they might need to use it again 

Don’t use reference numbers as confirmation only. 

#Allow people to copy and paste into forms

According to Harkla, dyscalculics struggle with some or all 7 visual perception skills.

  1. Visual discrimination is identifying differences in numbers like 5 and 2

  2. Visual figure ground is locating an item in a busy environment, like finding a reference number on a letter

  3. Visual sequencing is visually organising items in a specific order, like creating a number line

  4. Visual memory is recalling something seen previously, for example, a reference or verification number

  5. Visual closure is seeing part of an object and knowing what it is

  6. Visual-spatial processing is understanding where objects are in space

  7. Visual motor integration means hand-eye coordination

Most forms require us to use 1 or more visual perception skills.

#Designing for time blindness

Some dyscalculics experience time blindness which is more common for people with ADHD. 

Time blindness means someone:

  • overestimates or underestimates how much time has passed

  • can’t estimate how long a task will take

  • can’t say which two activities will take (or did take) longest


Dyscalculics struggle to tell the time, keep to schedules and understand units of measurement. People with ADHD feel that time is passing by without them being able to complete tasks accurately and well.

And people who are stressed (which is everyone at some point) report losing time.

Many services we use require us to tell or interpret time somehow, like:

  • timetables and journey planning

  • arranging and attending appointments 

  • authentication and security

  • online shopping baskets

  • bills and money management 

  • cooking and baking 


Authentication apps, government services, ticket sales websites and even entertainment like Netflix use countdown timers. But it’s common for dyscalculics and people with ADHD to start a task and walk away from it, only to be timed out and have to start again. 

Monzo says that people with ADHD spend £1600 more yearly because of difficulties managing money

Don’t time people out.