Memorize the digits, then
enter them in reverse order
2.5
Memorize...
🔄 Enter in reverse
Shown:
Answer:
Yours:
Streak: 0 | Level: 3
Memorize the digits, then
enter them in reverse order
Memorize...
🔄 Enter in reverse
Shown:
Answer:
Yours:
Streak: 0 | Level: 3
The backward digit span is a classic working memory task. Unlike forward recall, reversing a sequence requires holding the digits while simultaneously reordering them. This dual demand — retention plus manipulation — places sustained load on both the capacity and processing functions of working memory.
In the Baddeley and Hitch multi-component model of working memory, "holding" information and "manipulating or transforming" it are treated as distinct functions. Forward span primarily engages the phonological loop — temporary storage of verbal information. Backward span additionally recruits the central executive, the control system that organises and transforms held information. Backward span is therefore considered a more sensitive measure of working memory capacity that places greater demand on processing functions.
The average adult span is approximately 7 digits forward (Miller's "magic number") and roughly 5 digits backward; this gap reflects the cognitive cost of reorganisation.
Start at a level where your accuracy is around 70–80 %. Short daily sessions of 5–10 minutes tend to be easier to maintain than longer, irregular practice. Sustained, moderate load is the basic approach used in working memory research. If you hit a plateau at a particular span length, drop back by one or two digits, rebuild accuracy, and try again. A plateau is a sign that the brain is searching for a new strategy.
Reverse Digits is the foundation of the TOMOY working memory training series. Backward span provides the simplest form of the core demand — "hold and manipulate" — that underpins every other task in the series. All other tasks layer additional executive demands on top of this base.
Once comfortable, consider progressing to Ascending Digits (reordering), Dual-Task Reverse (divided attention), Filtered Digits (inhibitory control), and finally Transform Digits, which engages all three executive functions simultaneously.