I've used the techniques described here for as long as I can remember (over 30 years: man, how the years have passed!) and here's how I'd summarize my experience:

1) The techniques work well to impress your friends and family (you look like a genius weaving that magic) but better still, they work wonders for examinations that require lots of memorization (think history, biology, geography, chemistry, literature and so on.) In a world where we all agree memorization is not the best way to go, our education system can't seem to avoid it. These memory techniques help you to "tape" the facts and spit them out appropriately - no thinking, no stress. They've allowed me to get done with the memorization quickly, and move on to where logic and analysis is actually required. A double win.

2) The other great fear in life - public speaking - is also neatly handled. Among other things public speaking combines the recalling of the content of a story, and the presentation of that story. We fear we will forget on the one hand, and that we will screw up delivery on the other. These memorization techniques make the recalling a breeze, and allow you to focus on the presentation. Worth it's weight in gold.

3) Finally, on the questioning of the value of the "junk associations" connected with these techniques. As others have pointed out, the reality is our human mind creates mostly junk associations anyway. We remember what we remember only because those mostly junk associations are vivid. These memory techniques teach you how to make vivid whatever junk association you use via heightened or over exaggerated imagery.

What I've found is that while the short-term benefit is better short-term memory, in the long-term the exercise of such vivid imagery has made me much more creative in the way I see things. Sometimes crazy but mostly creative, and lots of non sequiturs that bring out a crazy sense of humor that keeps you chuckling along to better ideas.

To follow up with a bit more substance. Rather than sweat it out remembering something like this the hard way (and it would be hard using normal methods):

    91852719521639092112

It's a piece of cake remembering this instead:

    A beautiful naked blond jumps up and down.

The imagery is easy to conjure, and before I get hammered for sexism of any kind, imagine a beautiful naked blond of either gender. ;)

The key linking the two is this:

    1 : t, d
    2 : n
    3 : m
    4 : r
    5 : l
    6 : j, sh, soft g
    7 : k, hard g, hard c
    8 : f
    9 : p, b
    0 : s, z, soft c

A little bit of time and effort memorizing the key has allowed me to handle tables of numbers and dates of amazing sizes and lengths. Thanks to a book by Harry Lorayne I picked up by chance in my 9th grade. :)

I concur. I too chanced across that Harry Lorayne book in high school and it made rote memorization much less of a chore during those years :) Even now I occasionally use it for phone numbers.

For the others, this is the book: http://www.amazon.com/How-Develop-Super-Power-Memory/dp/0811...

He has many other books describing his techniques but that was easily the best one. I remember being able to memorize the sequence of half a deck of cards, forward and back, on my first attempt. It's amazing what you're capable of if you put the effort in (unfortunately I stopped...).

Why this specific mapping?

It's the one Harry Lorayne came up with. It could be any other mapping you choose, as long as you stick with it. However, in this method the use of consonants for numbers and vowels as fill-ins is probably already optimal. The Life Hacker post describes some other methods which I'm not familiar with. I plan to try them out to see if they are any more efficient. Memorizing a deck of cards in just over a minute, as described there, is very compelling. I've always required a little bit more time than that to do the same.

Others have commented on the lack of proof for the "cramped attic" theory of memory. Additionally, if you're trying to remember information that you'll use regularly, in my experience the more absurd imagery merely serves as the means of getting the information into long-term memory.

For example, occasionally I'll visit a train stop known as "7774". To check on the train arrival schedule if I'm not there yet, the simplest route is to feed that number into an Android app. Initially I used the ancient Major System of equating digits and consonant sounds, so 7774 becomes k-k-k-r, or "kaka car". (Think of a clown car driving past the stop, except it's filled to overflowing with poop instead of clowns.)

Now my point is that these days I only use the car association on those rare occasions when I momentarily block on the stop number. Normal usage brings up the stop number automatically -- without the poop car image. So it's not like my thinking is somehow cluttered with thousands of random images.

BTW, working on generating your own memory prompt images is effectively the same as practicing your creativity and lateral thinking skills. And that's a good thing, no?

Totally clueless about the science but assuming that "Ozzy Ozbourne" takes up more memory space inside our brain than 00 is a fallacy (mixing computers with brains). Imagery can be more efficient in some cases. Like the Chinese language where one character can express a complex object makes for faster reading since they are unique and translate instantly to images. It's more of a compression technique.

Pretend your memory is a hash table. You forget stuff because too much crap gets stored under the same few keys. So all the stuff that's mostly the same gets blended together in your memory. If you want to remember, the memory has to be unique. And those techniques are supposed to make things stand out.

That's why things people told me yesterday get blended together, but I'll probably be stuck remembering the "purple monkey dishwasher" thing for the rest of my life, even though I haven't seen that show in a decade or so.

All of these invented system carry their own pros and cons, but the aversion to "junk associations" is an extremely common misconception in my opinion (one that I held for quite a while as well). Many will argue that relative to your total cognitive power the cost is virtually zero but I don't think the discussion needs to go that way, and here's why: like anything, the beginner has to force everything. You put in the effort consciously because you recognize it as a step in some process. If the technique remains a novelty, then that's where you'll stay. Your associations may get ever more clever, simpler, faster, etc. But when you start to apply it constantly in your work and in everything else that you do, soon the technique simply fades into the background until at some point it might as well have disappeared. It's like math or spelling as a child, where you have to learn step by step what is and what isn't until it clicks, and then the why no longer matters. You add two numbers because that's the way it works– you don't have to convince yourself. As your memory progresses you the junk associations will fade out and stronger associations predominate, because they're relevant and you want to remember relevant things.

Edit: this is especially relevant to the "read me a list and I'll repeat it forwards, backwards, or in any order you call out" party trick.

I am not sure, but I do know that your brain is making associations with everything you experience, whether you like it or not. Might as well use those associations for something useful.

I thought of a simpler technique the other day that uses triggers like fear or pleasure. Fearful incidents people tend to remember very clearly. Imagine you have a big test and need to do a lot of memorization you could turn it into a fearful experience that will really burn it into your memory but without making dozens of crazy associations. Take a hammer, spread your fingers open wide on a table. Start saying out loud the things you need to memorize while hitting between your fingers with the hammer. I have not tried this myself but I am guessing that the information will be written to the brain as part of the fearful experience making the information easy to pull up for a test.

This technique does have a cost. Every time you activate your amygdala (which, in turn, activates your sympathetic nervous system, which primes your body for fight or flight mode), it becomes more sensitive both in the moment and the future. You don't want to be in fight or flight mode. It's enormously unhealthy and hard on your body. Moreover, it inhibits your medial prefrontal cortex, which is your "head" in coloquial terms, the region of your brain that houses rational, abstract thought, making it harder to think straight. Fear is the mind killer.

I think if you did that enough it would go the way of the crazed runner chasing dog technique that I used a few times.

It goes like this.

You are running and a dog chases you. So you run toward the dog acting like a lunatic. I've tried this and the dog does run away. But only the first time. The second time (that I tried) the dog was on to it and continued the confrontation.

What works for me is being very annoyed about something because I forgot it in a test. It's the best way to remember things so far - just do them wrong once when it counts.

I lost a spelling bee on "tawny" when I was a child. I had never noticed seeing or hearing the word before, but I sure noticed it when I saw it five years later.

I still vividly remember the moment a week later when I dislodged the lost and then found spelling bee study guide that was jammed behind the drawer of my nighttable.

I feel like it's worth it to remember people's names. I also don't think there's any evidence that indicates being better at remembering one thing makes you worse at remembering others. In fact it might even make you better, as you're sharpening your brain, so to speak. (If there's evidence to the contrary please feel free to share.)

There is some evidence that great memory comes at the cost of other functions like creativity. However, that may simply be because people with poor memory spend more time grasping at straws.

The cost is negligible with respect to the total carrying capacity of your brain. I don't have a source, but I've seen this stated in a few books.

It is often mentioned that there is a cost in that an additional association seems like more work. (To disclose my bias, I find visual memory techniques to be a boon to my apparently concept-driven mind.) Consider, however, that work must be done both when constructing the memory and also when repeating it. Visual memory, mnemonics, and the like, all work, I believe, because they increases the strength of the encoding, decreasing the need for repetition later. So, there may be more work upfront, but there is much less over the lifetime of the memory.

Good memory is both a curse and a gift. I hate remebering every single shitty moment in my life but I love being able to recap meeting minutes without notes at work.