The Working Memory Index (WMI) is a score from the Wechsler IQ tests that shows how well someone can hold information in mind and work with it. It’s a standard score: 100 is average for the person’s age, and every 15 points is one standard deviation (the typical distance from the average), so most people land between 85 and 115.
A WMI of 110 sits at the 75th percentile, at the bottom of the High Average range. That means the person did as well as or better than about 75 out of 100 people their age.
Working memory index score ranges
Pearson, the publisher, sorts index scores into labelled bands. The labels changed with the WISC-V in 2014. Adult reports from the WAIS-IV still use the older wording, so the same score can carry a different name on a child’s report and an adult’s.
| Standard score | WISC-V label | Older label (WAIS-IV) | Approx. percentile |
|---|---|---|---|
| 130 and above | Extremely High | Very Superior | 98th and up |
| 120 to 129 | Very High | Superior | 91st to 97th |
| 110 to 119 | High Average | High Average | 75th to 90th |
| 90 to 109 | Average | Average | 25th to 73rd |
| 80 to 89 | Low Average | Low Average | 9th to 23rd |
| 70 to 79 | Very Low | Borderline | 2nd to 8th |
| 69 and below | Extremely Low | Extremely Low | Below 2nd |
The percentiles here come from the normal curve for a mean of 100 and a standard deviation of 15. Your report takes its percentiles from the test’s own norm tables, so they can differ by a point. Reports also give a confidence interval, a range a few points either side of the score, because one sitting can’t pin the number down exactly.
What common working memory scores mean
A working memory score of 85
85 is the 16th percentile and falls in the Low Average band. It’s one standard deviation below the mean. About 16 in 100 people the same age score at or below it. That’s a relative weakness, not a disorder.
A working memory score of 100
100 is the exact average, the 50th percentile. Half of people the same age score higher and half score lower.
A working memory score of 110
110 is the 75th percentile and the lowest score in the High Average band. It means working memory is a bit stronger than most people’s: above average, but not rare.
A working memory score of 120
120 is the 91st percentile, the start of the Very High band on the WISC-V and the Superior band on the WAIS-IV. It’s well above average.
A working memory score of 130
130 is the 98th percentile, the start of the Extremely High (WISC-V) or Very Superior (WAIS-IV) band. Few people score this high.
Which subtests make up the WMI
The index is built from two subtests. Which two depends on the test:
- WISC-V (children aged 6 to 16): Digit Span and Picture Span. In Digit Span the child repeats strings of numbers in the same order, in reverse, and sorted from smallest to largest. In Picture Span the child looks at pictures, then picks them out again in the order shown. Letter-Number Sequencing is a secondary subtest. It pairs with Digit Span to give a separate Auditory Working Memory Index.
- WAIS-IV (adults): Digit Span and Arithmetic. Arithmetic means solving word problems in your head, without paper.
- WAIS-5 (published 2024): Pearson reworked the working memory section and added new subtests, including Running Digits. If your report is from the WAIS-5, check its own subtest list.
A big gap between the two subtest scores changes how to read the index. If Digit Span is strong and Picture Span is weak, the WMI is averaging an auditory skill and a visual one, so the psychologist will usually comment on the split rather than lean on the single number.
What a low working memory score can look like
Psychologist Susan Gathercole studied children with poor working memory in ordinary classrooms. She found they often:
- carry out the first step of a multi-step instruction and then stop
- lose their place in a task, skipping steps or doing them twice
- get described by teachers as not listening or not paying attention, not as having a memory problem
Her research also linked poor working memory with slower progress in reading, maths and science.
One index is not a diagnosis
A low WMI does not diagnose ADHD, dyslexia or anything else. Tiredness, anxiety, hearing problems, low motivation on the day and testing in a second language can all pull the score down. A psychologist reads the WMI next to the other index scores, the person’s history, school or work reports and how they behaved during testing. If the score worries you, ask the person who wrote the report what it means for this child or adult. They saw the whole picture.
How this site’s working memory test compares
The working memory test on this site is a backward digit span task: you see a string of digits and type them in reverse. That’s close to one part of the Wechsler Digit Span subtest. But it is not a standardised WMI. It isn’t given by a trained examiner, it isn’t normed on a sample matched by age, and it reports a level, not a standard score. You can’t turn your level into a WMI.
What it can tell you is how your result compares with other people online. See the average working memory score and the full working memory percentiles. For forward recall only, try the digit span test.
Frequently asked questions
What is a standard score of 110 for working memory?
It’s above average. A working memory index of 110 is the 75th percentile, so the person scored as well as or better than about 75 in 100 people their age. On both the WISC-V and the WAIS-IV, 110 is the bottom of the High Average band, which runs from 110 to 119.
Is a working memory index of 85 bad?
It’s below average but not unusual. 85 is the 16th percentile, in the Low Average band. It can mean school or work tasks that load memory feel harder, like following long instructions. It is not a diagnosis. Read it next to the rest of the report.
What questions are on a working memory assessment?
On the WISC-V the child repeats number strings forward, backward and in number order (Digit Span), and remembers a series of pictures in order (Picture Span). On the WAIS-IV, adults do Digit Span and solve spoken arithmetic problems in their head. Items get longer or harder as the test goes on.
How long is a working memory assessment?
The working memory subtests are only part of a full Wechsler test. Pearson gives about 60 minutes for the WISC-V core subtests. To check your own working memory, the working memory test on this site takes a few minutes, but it gives a level, not a WMI.
How long does working memory hold information?
Only seconds unless you keep repeating it. In a classic 1959 study, Lloyd and Margaret Peterson stopped people rehearsing by having them count backwards. Recall of short letter strings fell steeply within 18 seconds. Rehearsing, or grouping items into chunks, keeps them available for longer.
Is there a working memory IQ test online?
Not one that gives a real WMI. The index only comes from a Wechsler test given by a qualified examiner. Online tests like the working memory test here measure a similar skill and compare you with other people who took it, which is useful for tracking yourself but isn’t a clinical score.
Sources
- Pearson, WISC-V Interpretive Report sample: index scale (mean 100, SD 15), WMI subtests, Auditory Working Memory Index.
- Gloria Maccow, Pearson, Clinical Utility of the WISC-V (2014): WISC-V and traditional descriptive classifications.
- Pearson, WAIS-IV Score Report sample: WMI from Digit Span and Arithmetic, adult qualitative descriptions.
- Pearson, What’s new with the WAIS-5? (2024).
- Pearson, WISC-V product page: ages and administration time.
- Susan E. Gathercole, Working memory in the classroom, The Psychologist, British Psychological Society (2008).
- Peterson, L. R. and Peterson, M. J., Short-term retention of individual verbal items, Journal of Experimental Psychology (1959).