Processing Speed and Working Memory in Neurodivergence: What They Are and Why They Matter

There are specific criteria for ADHD and autism in the DSM5, but there are many other psychological differences that can co-occur. Processing speed and working memory are two cognitive functions that can quietly affect day-to-day life. These mental capacities often don’t get the attention they deserve, yet when processing speed or working memory are slower than usual, they can be problematic.

What Is Processing Speed?

Processing speed refers to how quickly a person can take in information, make sense of it, and respond. It’s not about intelligence or effort. It’s more like the mental “loading time” for a task.

People with slower processing speed might:

• Take longer to read or understand instructions, both written or verbal

• Struggle to keep up with fast-paced conversations

• Appear slow to respond, even when they know the answer

• Need more time to complete assignments or work tasks than other people

Processing speed can be slower, even in people with higher intelligence. This isn’t due to laziness or lack of interest—it’s a neurological difference that affects the pace, not the quality, of thinking.

What Is Working Memory?

Working memory is like a mental sticky note. It allows you to hold and manipulate information in your mind over short periods. For example, doing mental maths, remembering a phone number just long enough to dial it, or following multi-step instructions all rely on working memory.

When working memory is weaker, it can lead to:

• Losing track of what you were doing

• Forgetting instructions partway through

• Needing to reread information multiple times

• Trouble organising thoughts or writing clearly

• Feeling overwhelmed by tasks with several steps

How Cognitive Testing Measures These Skills

Cognitive assessments (often known as IQ tests) can provide insight into processing speed and working memory, as they are processes that are measured through the use of standardised structured tasks.

Processing speed is often measured using timed tasks that involve scanning, matching, or copying symbols or patterns. These tasks assess how quickly someone can take in visual information and respond accurately under time pressure.

Working memory is usually assessed through tasks that involve holding and manipulating information in your mind. For example:

• Digit span tasks, where you repeat sequences of numbers forward or backward

• Letter-number sequencing, where you re-order mixed lists of letters and numbers

• Visual working memory tasks, where you recall patterns or positions of objects

Cognitive testing is not a standard or required part of ADHD or autism assessments. I do not use cognitive testing in my assessments, but occasionally, an assessment client will have a previous cognitive assessment that they provide. I have often seen significantly lower scores in either processing speed, working memory, or both, compared to the person's general level of intellectual function. These outcomes can highlight potential difficulties the person is likely experiencing in tasks affected by these processes.

What Can Help?

Accommodations for slower processing speed or working memory difficulties are the mainstay of management. Stimulant medication can't be expected to improve these difficulties to average levels.

1. Externalise Information

• Use sticky notes, to-do lists, alarms, and visual cues to support memory.

• Write down steps before starting a task to avoid mental overload.

2. Allow Extra Time

• Advocate for extra time in academic or work settings where appropriate.

• Build in buffer time for transitions or complex tasks.

3. Break Tasks Into Smaller Steps

• Tackling one piece at a time helps reduce overwhelm and improves follow-through.

4. Minimise Distractions

• A quieter, calmer environment can help compensate for slower processing.

5. Use Repetition and Routine

• Repeating information or routines can strengthen retention and reduce the load on working memory.

7. Medication and Therapy

• ADHD medications may improve attention and cognitive processing in some people.

• Therapy can help develop strategies and improve confidence.

Final Thoughts

Processing speed and working memory challenges are often invisible but very real for many neurodivergent people. Understanding these cognitive functions can bring relief—it’s not a character flaw or a failure of willpower but a difference in how the brain works.

With the right supports and strategies, it’s possible to work with these challenges instead of against them.