Coding Mnemonics

Coding Mnemonic: A System for Remembering Numbers

Most people find numbers such as phone numbers, personal identification numbers; dates, and so on more difficult to remember than words. That is, of course, why businesses try to get numbers that corresponds to some relevant word.

The system whereby this is possible — the linking of certain letters to the different digits on a telephone calling pad — is a kind of coding mnemonic. Basically, coding mnemonics are systems that transform numbers into words.

Because words are much easier for most of us to remember, this is a good way to remember numbers, but it’s not the only one. If you have a facility for numbers, or an existing store of memorized numbers (dates, baseball scores, running times, whatever), you can use those memorized numbers or your understanding of mathematical patterns to remember new numbers.

In one well-known experiment, for example, the subject was able (after 250 hours of practice!) to recall up to 82 digits after hearing them at the rate of one digit a second. This subject was a runner, and used his knowledge of record times to make the digit strings more memorable.

The difficulty with a coding system is that you can’t use it effectively until you have fluently memorized the codes, to the extent that the linked letter (if encoding) or digit (if decoding) comes automatically to mind. This requirement makes this sort of mnemonic the costliest of all the mnemonics — that is, it takes the most time and effort to master.

Of course, the pegword mnemonic is also a coding system, in a way — which is why it’s harder to master than the method of loc. But the pegword mnemonic is easier than the digit-letter substitution mnemonic. There are two reasons why:

1. the pegs and their numbers are connected by simple rhymes;
2. the construction of a composite image incorporating the peg and the item to be learned is less constrained than the finding of a suitable word constructed from the required letters.

As implied by the author, this is what is meant. First, here is the best-known digit-letter code — it’s important to note the system is based on sound rather than actual letters, so various similar sounding letters are regarded as equivalent:

Now these substitutes weren’t chosen arbitrarily. The inventor has tried his best to make them easy to remember. But as you can see, some of the rationale are somewhat contrived. If you think you can come up with codes that are easier for you to remember, feel free to change them — just bear in mind the dangers of confusability. For example, you could code f for 5, but there is a strong risk of becoming confused between 4 and 5 when decoding.

Once you’ve encoded the digits into letters, you can turn into words or phrases or rhymes. Only consonants are used for coding. This means you can throw vowels (and also, in this system, w, h and y) in as necessary.

In this way the date 1945 could be encoded as tprl, which could be turned into top role, to pour low, tie a poor owl, tip or lie, top rail. Or dprl: die poorly! tbrl: tuba role; dbrl: dab rule.

You see what I mean about constraints. However, there is enough give in the system to make it possible to always come up with something.

If you do want to learn this particular system, there is a mnemonic that may help you memorize the 0-9 codes (from Bower, 1978): Satan may relish coffee pie. Why will help you remember which consonants can be used freely, like vowels.

The system also allows you to use doubled consonants where the sound doesn’t change (which is mostly). For example, dipper, dabble, squirrel. Compare these to accent, where the first c is hard (7) and the second c is soft (0).

Similarly, a silent consonant doesn’t count. Thus knee equates to 2 and not 72. Less obviously, words like would, could, should don’t count the l. But I’m not sure I like this myself. I’m very aware of how words are spelled, and tend to ‘see’ words as I hear them. I think whether or not you count silent consonants depends on your awareness of what the words look like.

A similar issue of personal preference is whether you regard ng as a variant of hard g (7), or two sounds: n and g (27).

x generally makes the sound of ks (70), but when it starts a word (xylophone, xenon) it’s often more a soft z sound (0).

You can see why this system takes more training than the other systems! And why this mnemonic is the least studied of the major mnemonics. In those few studies that have been done, there are usually only one or two subjects. This is not surprising when you consider the number of hours needed to achieve mastery of this system. These studies have invariably focused on training their subjects to memorize very long strings of digits quickly. It’s hard to imagine the everyday circumstances in which this would be a useful skill for most of us.

Having said that, there a number of occasions when you want to remember shorter numbers — say four, or seven, or even nine digits. And the code really isn’t as hard to learn as it might seem, looking at it. A little practice coding numbers into letters, and back again, works wonders in cementing this in your brain.

One study that did involve a number of students, and, most interesting of all, did compare the performance of students who learnt the mnemonic with the performance of students instructed in general cognitive strategies (such as chunking Opens in new window and clustering) but not mnemonics, found impressive results with the mnemonic.

Over 45% of the mnemonic students recalled all 20 digits in a 4x5 matrix, compared to 7% of the cognitive students. Over 85% recalled at least 16 digits, compared to 35%. Even more impressively, 43% recalled all 50 digits from a 50-digit matrix (4x12+1x2), and 78% recalled at least 45. The comparison group in this case were general psychology students who had received no particular cognitive training — none remembered more than 34 digits.

Indeed, only 3 of the 37 mnemonic students who learned the 50-digit matrix did as badly as any of the general students, and those 3 had all failed to learn the mnemonic properly.

The mnemonic students had spent four 75-minutes classes studying the mnemonic, plus about an hour’s practice outside class. They studied (but didn’t memorize) a list of 100, but didn’t have much practice memorizing matrices (one 60-second practice with a 20-digit matrix).

Keeping it simple

• Remember the codes with: Satan may relish coffee pie
• Vowels and consonants why don’t count
• Avoid x, ng, silent consonants.
• Remember doubled consonants that sound like one only count as one
• Remember it’s the sound that matters.