Person-Action vs. Person-Action-Object vs. 3-Digit Systems
hen I was deciding on what kind of memory system to use, I made a chart to compare the efficiency of different systems.
The comparison was between:
- a 2-digit person-action (PA) system
- a 2-digit person-action-object (PAO) system
- a 3-digit system where three images are placed in each locus, which could be PAO or arbitrary
I’m not claiming that one system is necessarily better than another; I’m only sharing a bit of the research that I did before I chose a three digit system. :)
Here is the chart:

By the 25th location, the three digit system can store 225 digits in 75 images compared to 100 digits in 50 images ¶ or 150 digits in 75 images (2-digit PAO).
What do you think? Does the difference lead to a boost in performance? Is there an even more efficient system than the ones listed above?
In the end, one of the reasons I went with Ben Pridmore’s system because it’s incredibly efficient for binary numbers. By the 25th locus, it can encode 750 binary digits, using the same images as for the 3-digit decimal system and cards.
Update: read about a 4-digit system with 10,000 images.