This filmstrip metaphor is not technically accurate in terms of psychology. But I find it convenient as a visual reference, and I don’t think it is too misleading. In fact, I remember many years ago reading about a cognitive psychology concept known as Rapid Attentional Integration (RAI). I have borrowed this filmstrip metaphor from that reading. The idea is to imagine that all kinds of preconscious processes have already formed percepts for each sense, and that some higher-order process has now integrated all of those percepts into a pre-organized and partially interpreted snapshot of reality. It is this snapshot that is presented to your conscious mind, at a rate of some ten frames per second or so.

At this moment—when you first become conscious of the sensory input and can attend to its many components—the information reaches the highest level of sensory memory and enters short-term memory—allowing you to think about it and to make decisions based on it.

As shown in the illustration, a lot of time has passed since the filmstrip appeared with the list elements—they are all fading from memory as you reflect on them. You are now in a present in which your attention is focused inward—on trying to remember the vanishing list of restaurant names. That is why it is important to turn down the gain on your incoming movie by remaining quiet. Otherwise, new information will interfere with your ability to remember the immediate past.

Notice that the names—shown in the cloud that you are seeing in your “mind’s eye”—are already somewhat jumbled. The first thing that fades is the exact ordering of the names. You may remember one or two, but not be able to recollect which came earlier and which later. You are also more certain about specific ones—shown in a black font—that seem to be more vivid for no apparent reason. Others are dim and foggy. Maybe you only remember parts of some of the names, for example, “Chez some-thing-or-other.”

As shown in the illustration, you can only hold a few items in memory at a time. So when you get to the end of the list, there are only a few “ghosts” remaining. You’ll find that’s true for your colleagues as well. Some people may remember as many as nine restaurants or so—although probably the number is much smaller. I wouldn’t be surprised to see some sheets with only two or three names on them. Many of your group may well remember the last restaurant, because it was the most recent to reside in sensory memory.

Perhaps—after some thinking, you might come up with some extras:

(illustration, a handwritten list as one may have written them down for the exercise—a couple of common franchises, plus a “wrong” memory that contains a partial restau-rant name, and another “gummy something” instead of Yummies Greek Treat.) The names are: Benny’s, OneGreatBurger, Taco Guano, and Jack of Club Sandwiches.

Look at these last ones. Now look inside your own mind. You didn’t really remember them at all, did you? You reconstructed them from your world knowledge. Maybe the franchises—Benny’s, OneGreatBurger, Taco Guano—were a little easier because they’re commonly known. Does that make them easier to remember? No, probably not. Instead, what you have in your vanishing memory of the auditory list is a remnant that you have reconstructed from long-term memory. In other words, your knowledge of fast-food chains, plus a little reference to an echoic memory that is rapidly degrading, allows you to hypothesize that you “heard” these choices—even though you don’t really remember hearing them per se.

You can test this effect yourself. Build two lists. One, a random collection of unrelated words with no context. The other, a list of related choices including some commonly-known items—perhaps restaurants as shown here—or colors, celebrity names, nations of the world, or a list of animals. Make the list too long to remember on a single presentation (15 or 20 will do fine). Then read the list aloud once to a friend. Have her write down everything she remembers—not during the presentation, but immediately afterwards. Remain silent while she writes.

These kinds of tests are very easy to run, remarkably effective at teaching you the basic constraints of human memory, and surprisingly consistent. You will find natural variation from person to person, but on the whole the number of items remembered correctly will cluster into the shape of a bell curve as you sample more people. The longer the list, the more rapidly the curve will slope off. The tails of the curve will be fairly predictable—everyone will remember at least one item, and no one will remember all items.

If the list is long enough and contains commonly-known elements (as in the restaurant example), you might see false positives. That is, some people will “remember” restaurants that were not actually spoken. Such occurrences will increase with the length of the list and with the commonness of the items. If the list is arbitrary, false positives will go down but the total number of remembrances will also drop.

One final variation on this theme: try assembling two lists. Read the first one aloud. Then hand the second printed list to the friend. Have the friend check the words on the second list that were in the verbal presentation. Have the friend X the words that were not in the verbal presentation. On any for which she’s not sure, have her make no mark. You can repeat this across many friends and plot both the negatives and positives on a graph.