Hack89.Navigate Your Way Through Memory

Hack 89. Navigate Your Way Through Memory

A 2,500-year-old memory trick shows how our memory for events may be based on our ability to remember routes to get to places.

Remembering where you are and what is currently happening are (as you might expect) both rather important. It turns out that orienting yourself in space may rely on some of the same brain areas as are used for remembering what has happened to youareas that originally evolved to help animals find their way around, but now allow us to retain the episodes that make up our personal narratives.

The demonstration we'll use is a famous memory trick used to remember a list of arbitrary things, with the added bonus that the things are remembered in order. It's called the method of loci and involves remembering things according to where they are positioned along a route. Simply take your list of things to remember and place them along a familiar route, imagining each item (or something that will remind you of it) at key points on the route.

9.10.1. In Action

How many words do you think you could remember if given an arbitrary list and around 10 seconds per word in which to learn them? Knowing that my memory isn't all that good, I thought perhaps I could remember around 10. So I decided to use the method of loci to remember 20 words, twice that number. I didn't want to come up with my own list, because it would be easier for me to remember, so I used the 20 most common words appearing in the lyrics of the songwriter Tom Waits, as kindly provided by the excellent Tom Waits Supplement (http://www.keeslau.com/TomWaitsSupplement/Lyrics/common.htm) and shown in Table 9-5.

Table 9-5. Imagine an item for each word at points along a route that is familiar to you. Rehearse for 4 minutes and then test yourself

1. NIGHT	8. HOME	15. DRINK
2. TIME	9. RAIN	16. STREET
3. LOVE	10. HEART	17. BLOOD
4. DAY	11. DEATH	18. RED
5. EYE	12. DOG	19. HAIR
6. DREAM	13. BLUE	20. GIRL
7. MOON	14. ROAD

Perhaps you think 20 is too easy; feel free to use a longer list or give yourself less time, if you're so inclined. But 20 in 4 minutes seemed daunting enough for me. Starting with "night" (131 mentions across Tom Waits' entire discography) and finishing with "girl" (40 mentions), I imagined something to do with each item at each point of the journey from the front room of my house, where I was sitting, to my nearest subway station.

After mentally doing the journey and noting the items strewn along the way (a "love" letter at the foot of the stairs, a "drink" of coffee at the café on the corner, and so forth) and checking that I thought I'd remembered them all, my 4 minutes were up and I pulled out my notebook and got my pen ready to write down the list of items.

Normally with things like this my mind goes blank as soon as the thing I'm supposed to be remembering leaves my sight. But, using the method of loci, I was impressed with how quick and easy it was to remember all the words. (Yeah, yeah, I know I'm supposed to know that it works, but I still managed to impress myself.) I got every item right, and only two out of order.

Try it yourself. It doesn't have to be these words. It can be things, people, numbersanything. This is one of the tricks professional memory artists use to remember lists of hundred, or even thousands, of things.

9.10.2. How It Works

The are several reasons this method works to help aid your memory, but the main one is the attaching of things to locations in space.

The memory technique also benefits from something inherent in the dual structure of navigating: the landmarks and route mutually define each other, but each exists in its own right. The route allows you to chain from one memory item (or landmark) to the next. Because the landmarks exist apart from the route, even if you can't remember what is at a particular location, it doesn't have to stop your journey onto the next location or item.

T.S.

We know that the human brain has specialized mechanisms dedicated to remembering landmarks,¹ and that (interestingly) this region and those nearby seem to be responsible for giving humans and other animals a sense of where they are in space.² Brain imaging of people navigating through virtual environments has shown that even if we don't consciously recognize something as a landmark it still triggers a response in this specialized part of the brain.

This part of the brain, the hippocampus and nearby nuclei, is also known to be absolutely crucial for storing our memory for events. Psychologists call this kind of memory episodic memory, to distinguish it from memory for facts or memories of how to do things. People with hippocampal damage (like the hero of the film Memento (http://www.imdb.com/title/tt0209144), for example) aren't able to store new episodic memories, although they can retain memories for episodes that they stored before their injury and they can learn new facts (with lots of effort) and skills.

So we know that this same part of the brain, the hippocampus, seems to be crucial both for recording events and for helping us understand where we are in space. Evidence that this first function may have evolved from the second has recently been published.³ It was found that the expectations and intentions an animal has affect how the hippocampus encodes memory for locations in the hippocampus. This encoding of context for locations at different times may have laid the foundations for the encoding of context in time for other memories. From this may have developed the memory for events, that ability to mentally time travel, which makes up what most of us think of as our memories.

9.10.3. In Real Life

You can see this landmark-specialized processing at work when we give and follow directions. If you are following directions and go past something that's an obvious landmark and your directions don't specify it, you know something's wrong. Interestingly there is also evidence from brain imaging that supports the well-known fact that men and women tend to navigate in a different manner; women tend to rely more on landmarks alone, whereas men rely more on absolute spatial position (the geometry of the situation) in combination with landmarks.⁴ The information architect Christina Wodtke has observed that "On the Web, everyone's a woman," because there is no consistent spatial geometry; we are all forced to rely on landmarks.5

9.10.4. End Notes

1. Janzen, G., & van Turennout, M. (2004). Selective neural representation of objects relevant for navigation. Nature Neuroscience, 7, 673-677.

2. Burgess N., Maguire, E. A., & O'Keefe, J. (2002). The human hippocampus and spatial and episodic memory. Neuron, 35, 625-641.

3. Ferbinteanu, J., & Shapiro, M. L. (2003). Prospective and retrospective memory coding in the hippocampus. Neuron, 40, 1227-1239. Discussed in Jeffery, K. J. (2004). Remembrance of futures past. Trends in Cognitive Sciences, 8, 197-199.

4. Gron, G., Wunderlich, A. P., Spitzer, M., Tomczak, R., & Riepe, M. W. (2000). Brain activation during human navigation: Gender-different neural networks as substrate of performance. Nature Neuroscience, 3, 404-408.

5. Wodke, C. (2002). Information Architecture: Blueprints for the Web. Pearson. (See the sample chapter at http://eleganthack.com/blueprint/sample.php for the particular observation.)