Low Working Memory: Signs in Adults and Children, and What Helps

People with low working memory tend to lose track of instructions before they finish them, forget where they are partway through a task, and struggle to handle several things at once. Working memory is the ability to hold information in mind for a short time while processing it. This article covers the signs in children and in adults, how working memory relates to IQ and ADHD, and why reducing the load works more reliably than trying to expand capacity, all based on research.

What working memory is: about four items at a time

Working memory is what holds the information you need for a few seconds to a few tens of seconds during conversation, calculation, or reading, so that you can think with it. You use it when you keep an intermediate result in mind during mental arithmetic, or when you plan a reply while listening to someone.

Its capacity has a clear ceiling. After reviewing a wide range of experiments, the psychologist Nelson Cowan concluded that people can hold about four chunks at once on average, with a range of three to five (Cowan, 2001, Behavioral and Brain Sciences). The familiar figure of seven plus or minus two comes from Miller's 1956 paper (Miller, 1956, Psychological Review), which Cowan characterizes as a rough estimate.

A small capacity is not quite the same as a poor memory. It concerns not your store of knowledge and experience but the workbench where you set information down for the task in front of you. When the workbench is narrow, each new piece of information pushes out an earlier one.

Signs of low working memory in children

Researchers have described what low working memory looks like in the classroom. A guide for teachers by the British psychologists Susan Gathercole and Tracy Alloway lists the following (Gathercole & Alloway, 2007, Understanding Working Memory: A Classroom Guide).

• Forgetting part or all of instructions or messages
• Losing their place in complicated tasks, which they may eventually abandon
• Not seeing tasks through to completion and appearing not to have paid attention
• Being reserved in group activities and rarely volunteering answers
• Making poor progress in reading and mathematics
• Being seen by teachers as having a short attention span and being easily distracted

The same guide notes that these children are typically well adjusted socially. What matters is that these are failures that occur when the amount to be remembered exceeds capacity, not problems of motivation or character.

The effect on learning is large. In a study that gave working memory tests to 3,189 children aged 5 to 6 and 8 to 9 in the UK and examined those scoring in the bottom 10%, 63 to 68% had low reading scores (standard scores below 86) and 65 to 71% had low mathematics scores. Teachers also rated them high on inattention (Alloway and colleagues, 2009, Child Development).

Difficulties adults with low working memory tend to notice

The mechanism is the same in adults: difficulties arise in situations where a lot has to be held in mind. At work and at home, these are typical.

• Losing the second half of a set of spoken instructions
• Losing your place in a task when someone speaks to you partway through
• Finding it hard to take notes or organize your thoughts while listening in a meeting
• Struggling to keep earlier content in mind while reading a long text
• Forgetting intermediate numbers during mental arithmetic or when working out change

Research also links individual differences in adult working memory to how easily attention is sustained in everyday life. In a study that prompted 124 undergraduates eight times a day for seven days to report what they were thinking, people with higher working memory capacity kept their thoughts on task better during activities that demanded concentration and effort, while those with lower capacity mind-wandered more (Kane and colleagues, 2007, Psychological Science).

These difficulties also arise from sleep deprivation, fatigue, and simply having too many tasks on the go (see sleep and cognition and multitasking and switching costs). Matching the signs does not, by itself, mean your working memory is low.

Working memory and IQ: correlations of about 0.5 to 0.7

Working memory and IQ are closely related, but they are not the same thing. A meta-analysis of 86 samples found a correlation of 0.48 between working memory and general intelligence (Ackerman and colleagues, 2005, Psychological Bulletin). Another analysis, looking at latent variables with measurement error removed, found a median correlation of 0.72, meaning the two share about half of their variance (Kane and colleagues, 2005, Psychological Bulletin).

Either way the correlation is not 1, and some people with low working memory do well on reasoning or vocabulary. Wechsler tests report working memory as a separate index, the Working Memory Index. In the Japanese edition of the adult WAIS-IV it is measured with Digit Span and Arithmetic (Nihon Bunka Kagakusha, WAIS-IV), and in the WISC-V for children with Digit Span and Picture Span (Nihon Bunka Kagakusha, WISC-V). How to read gaps between indexes is explained in how to read WISC results.

Working memory, ADHD, and developmental disorders

Children with ADHD tend, on average, to score lower on working memory tasks. In a meta-analysis of 26 studies, the difference from children without ADHD (effect size) was 0.85 for spatial storage, 1.06 for tasks that require manipulating spatial information, 0.47 for verbal storage, and 0.43 for manipulating verbal information (Martinussen and colleagues, 2005, Journal of the American Academy of Child & Adolescent Psychiatry). The gap is larger for locations and shapes than for words.

This is a group average, however. Some people with ADHD have high working memory, and low working memory does not mean someone has ADHD. Diagnosis is made by a physician from the overall course of behavior and is not determined by a test score. See ADHD and IQ for more.

Reducing the load works better than training

Working memory training improves performance on the trained tasks, but effects on other abilities have not been confirmed. A meta-analysis of 23 studies concluded that there was no convincing evidence that training generalizes to verbal ability, nonverbal ability, attention, word decoding, or arithmetic (Melby-Lervåg & Hulme, 2013, Developmental Psychology). A 2016 analysis extended to 87 studies reached the same conclusion (Melby-Lervåg and colleagues, 2016, Perspectives on Psychological Science).

What researchers recommend, therefore, is not trying to increase capacity but reducing the amount that has to be remembered. The principles in the classroom guide apply equally to adult work and daily life (Gathercole & Alloway, 2007).

• Break instructions into short pieces: give (or ask for) one or two at a time and move on once they are done
• Write things down: keep a record outside your head with notes, checklists, and written procedures
• Repeat important information: say it back, and keep it in a form you can look at later
• Simplify the task: cut down on situations where you must remember while doing something else, and finish one thing at a time

Reducing interruptions, for example by turning off notifications, also helps you avoid losing what you are holding in mind. Strategies like these place memory outside the head, which is also called cognitive offloading (see AI and cognitive offloading). Everyday practice methods are covered in how to train working memory, and the effects of games and musical training in video games and cognition and music and IQ, each together with the limits of the research.

Getting a sense of your own cognitive strengths and weaknesses

Measuring working memory accurately requires a professionally administered test such as the WAIS or WISC. BrainRank's test measures reasoning with figures and is not a test of working memory itself, though questions that require tracking several rules at once do draw on the ability to hold information while thinking. BrainRank's free IQ test scores 20 questions (about 10 minutes) across four domains, spatial reasoning, pattern recognition, logical reasoning, and classification, using item response theory (IRT), and returns an estimated IQ on a mean-100, SD-15 scale along with your strengths and weaknesses by domain. Taking it is free with no signup; viewing the results, including the estimated IQ, is a one-time payment of ¥300 (tax included), with no subscription or auto-renewal (the result can be reopened for 24 hours after it is first shown, and saved as an image or PDF during that window). Results are estimates for entertainment and self-understanding, not a medical or diagnostic assessment.