Each station, such as the mirror and sofa, is now connected to a particular item. If the following week's list contains a chocolate bar but no cereal, then the bookshelf would be made of chocolate, but the thick book would be missing. This way, various shopping lists can be remembered, with commonly purchased items such as eggs appearing regularly and occasional items such as a chocolate bar appearing sporadically when needed.

Once you have worked with a set sequence for some time--say, 10 locations in each of three rooms--more rooms can be added, increasing your memory storage capacity. Regular training is required for success, however. "Without constant practice," states an anonymous Roman book of rhetoric, Ad Herennium, "the rules will be practically useless. You must see to it that you have as many locations available to you as possible. The insertion of images must be practiced on a daily basis." Adept students of the discipline can build up an incredible number of locations. In modern-day memory competitions, contestants may memorize more than 1,000 numbers in a sequence or playing cards shuffled randomly in multiple decks. Some individuals can repeat a lengthy poem in its entirety after hearing it only once and can retell it with the stanzas in reverse order.

With practice, you can build your visual maps to great degrees. One predecessor of today's memory champions was Peter of Ravenna, a jurist in the late Middle Ages and author of a Latin handbook on memory strategies. Peter traveled extensively in Italy, and whenever he arrived in a new city he would visit churches and cloisters and memorize their layouts. Over time he built up an impressive collection of remembered spaces--more than 100,000 locations, according to his own claims. Whether or not that number was true, he could recite in public entire law books with commentaries, innumerable Bible passages as well as hundreds of classical quotations. Given those feats, the rest of us should at least be able to handle a trip to the grocery store.

Four hundred years later Roman rhetorician Cicero (106-43 B.C.) related Simonides' story in one of his instructional books on learning and memory. Whether the diners' deaths actually happened is not clear, but according to legend, Cicero wrote, the ceiling collapse motivated Simonides to develop a visual memory technique that still prevailed in Cicero's day, used widely by the Roman Empire's politicians and lawyers. These professionals were looked down on if they could not memorize the long speeches they often had to give; it was important for them to recite complex strains of an argument in moving oration.

Many people who exhibit extraordinary memory capabilities use this technique, including winners of world memory championships. Although the method may seem peculiar at first, any person can use it to improve their recollection of anything, from shopping lists to lecture outlines. Once you find a way to "see" the items you must remember, you can use the trick on different strings of information. Most current self-help books on improving memory or mental acuity also endorse this method, using, of course, modern strategies--and environments--that build on this ancient approach.

Soap Cushions

The mnemonic device, known as the loci method, involves placing mental pictures of items in specific locations inside a room, in a specific order. A person can then "walk" through the room and see all the objects that must be recalled. Each person must develop his or her own locational system. Teachers in antiquity recommended using public places such as temples or meeting houses as sites for spatial memory training; an individual would stand inside a temple and memorize the position of each column and statue, from the main entrance, along the right wall, across the front, back down the left wall, and so on. Each item from a list would then be assigned to a column, statue or other feature, in a given order. Later, the memorizer would visualize the room to find each item.

As an example, let us say you are going grocery shopping and have nine items to remember: eggs, cheese, spaghetti, fish, bread, soap, butter, salami and cereal. Imagine three rooms in your home, each containing three items from the list. You enter the foyer and hang your keys on the hook shaped like a loaf of bread. You walk across the rug, but it is made of salami slices, and look into a mirror that has two fried eggs stuck to it. In the living room, the TV has become an aquarium in which a big fish swims. The fish is looking across the room at the radiator, on which a stick of butter sits, melting. The melting butter drips down onto the sofa, whose cushions are made of bars of soap. In the den you see a computer mouse nibbling at some cheese. The bookshelf above it supports a thick book--the cereal box--and the curtain rod over the window is holding curtains made of woven spaghetti.