Answer fast, then refocus
Spend as little time on each sum as you can. The longer you look away, the more the list fades.
glance · decide · back to letters
WHY THE SUMS?
Storage is easy. Storage while working is the real test.
In Digit Span you can rehearse freely. Here, every sum interrupts your rehearsal, so you have to protect the letters with attention instead. Psychologists call this a complex span task.
That's why it's shorter than digit span, and why it predicts reading comprehension and reasoning better than simple span tasks do.
Simple span
7
Hold a list with nothing else to do.
Complex span
4–5
Hold a list while solving something else.
Six ways to keep the letters
The trick is protecting the list while your attention is on the sum. Try one per round.
Rehearse in the gaps
Say the letters silently in every tiny pause, while the next sum loads, before you tap.
“K… K-R… K-R-P”
Make them a word
Turn letters into a word or name as they arrive. K-R-P can become “KaRP”.
F · L · T → “FLaT”
Chunk in pairs
Group every two letters so a set of six is only three things to hold.
KR · PL · ST
Keep sums above 85%
Research versions only count scores when maths accuracy stays high. Don't sacrifice the sums to save the letters.
accuracy ≥ 85%
Rebuild from the start
If you blank on the recall screen, restart from the first letter, the sequence often comes back as a whole.
1st → 2nd → 3rd…
INSIDE YOUR BRAIN
Which parts of your brain Operation Span uses
Switching between sums and letters puts the frontal lobes in charge. They keep the letters safe while other areas do the maths and store the list.
1
Based on Gray's Anatomy, fig. 728 (public domain)
Dashed = deep inside the brain, not on the surface
Dorsolateral prefrontal cortex
Frontal lobeBoth sidesIts job
Guards what you’re holding against interference.
In this game
Keeps the letters alive while your attention is on the sum.
Anterior cingulate cortex
Frontal lobe, midlineBoth sidesIts job
Notices conflict and switching demands.
In this game
Handles the constant jump between maths and memory.
Posterior parietal cortex
Parietal lobeBoth sidesIts job
Supports attention and number processing.
In this game
Helps check each sum quickly.
Broca’s area
Frontal lobeLeft sideIts job
Plans speech, including your inner voice.
In this game
Rehearses the letters in the short gaps between sums.
1989
A test built to predict thinking
Marilyn Turner and Randall Engle introduced operation span at the Georgia Institute of Technology. They wanted a memory test that tracked how well people actually think, not just how many items they can repeat.
Complex span scores went on to predict reading comprehension and fluid reasoning, and an automated version from 2005 became a standard research tool.
SourcesTurner, M. L. & Engle, R. W. (1989). Is working memory capacity task dependent? Journal of Memory and Language, 28, 127–154.Unsworth, N., Heitz, R. P., Schrock, J. C. & Engle, R. W. (2005). An automated version of the operation span task. Behavior Research Methods, 37, 498–505.Conway, A. R. A. et al. (2005). Working memory span tasks: a methodological review and user's guide. Psychonomic Bulletin & Review, 12, 769–786.Kane, M. J. & Engle, R. W. (2002). The role of prefrontal cortex in working-memory capacity, executive attention, and general fluid intelligence. Psychonomic Bulletin & Review, 9, 637–671.
WHAT THIS GAME TRAINS
Remembering while you work
Solve a simple sum, then remember a letter; repeat. Recall the letters at the end. Because you're processing and storing at once, it's one of the best measures of working-memory capacity.
corestrongsomelight
coreWorking memory capacityHolding letters while doing something else.
strongDivided attentionSwitching between maths and memory.
someMental arithmeticChecking each sum quickly.
strongInterference controlKeeping the sums from wiping the letters.
REAL-WORLD MOMENTS
Pick a moment to see what's going on
Tap a situation to see which part of the skill it relies on.
SKILLS THESE MOMENTS DRAW ON
Working memory capacitycore
Divided attentionstrong
Mental arithmeticsome