Hack84.Keep Your Sources Straight (if You Can)

Hack 84. Keep Your Sources Straight (if You Can)

When memory serves up information upon request, it seems to come packaged with its origin and sender. But these details are often produced ad hoc and may not fully match the true source.

Every memory has a sourceor at least it ought to. That said, memories can often float loose from their moorings, making it some achievement that we manage to anchor mnemonic detail to their origins.

9.5.1. In Action

This test involves word stems, the idea being to complete the beginning of each stem in Table 9-2 with a word of your choice. So ple___ (complete it with any number of letters) could be "please," or equally "pledge," "pleat," and so on. Complete the odd-numbered stems (the ones on the left) out loud; for the even-numbered ones (on the right), merely imagine saying the words. Use a different word for each stem (i.e., don't use "please" twice if you run across the ple___ stem twice).

Table 9-2. Stem completion task. Think of a word to complete each stem. Speak the ones on the left out loud, but the ones on the right just in your head.

Complete out loud	Imagine completing out loud
1. BRE___
	2. MON___
3. FLA___
	4. TAR___
5. SAL___
	6. FAL___
7. SPE___
	8. BRE___
9. TAR___
	10. SPE___
11. MON___
	12. SAL___

Take a break! This is a memory test, so you need to pause for 1 or 2 minutes before reading on.

Now see if you remember your two fla__ words (it should be fairly easy) and whether they were spoken or imagined. You've got a fair chance of being right, although you'd likely make a few slips across the whole list. Try the whole list if you like, giving both items and whether you said them out loud or in your head: bre__, spe__, sal__, tar__, mon__, and spe__. It's probable that you can remember what you said for most words, and usually whether it was spoken or imagined. But while this is not an impossible task, you are in no way guaranteed to get the source of a recalled item correct.

Now in the traditional view of the mind, the idea that memories could stray from their true contextthat there is no master index putting all our memories in their placeis rather troublesome. On the other hand, consider what was done: when you come to look back, you have memories that are in most respects equivalentfor both spoken and imagined answers, you are left with a purely mental record of you saying the word. At the time, saying the word out loud was different from just imagining it, but now all that remains of both events is just an internal image of you saying the word. Yet, somehow, for the most part, we can distinguish the real event from the imaginary kind. That you've done it at all seems a testament to the memory system, as there are no obvious hooks to pull apart the problem.

Let's dig a bit deeper into this...

9.5.2. How It Works

If memories were itemswhole events that were fed into memory from an ideal memory systemit would be odd for us to retrieve a detail stripped of context. In the previous task, this would be knowing a word but not knowing if it were really said; but other mistakes taken from research include confusing the gender of the voice that spoke a word, or whether information was presented in the lab, learned outside it, or given in an audio or visual modality. The fact that we can make these errors pushes us to accept that memories are not holistic (read: nicely packaged) entities. Given further consideration, it is hard to imagine how they could be so and still be useful.

Consider this: how could you (or your brain) objectively and instantly demarcate the boundaries of what constitutes a single event? An event is as long as a piece of string, just as an "item" is as many features as you need to make that item. Figuring out what an "event" or "item" is, is an implausible task. If the brain were to attempt it, we would be stuck halfway to nowhere.

Once we reject this view and, in so doing, are freed to look at memories as collections of features, we can again wonder how it is that we can reconnect a memory detail with its source. This is a property memory needs to function well, so it should come as no surprise that the brain has found a solution. This is the use of multiple processes (parallel processing is a common pattern [Hack #52] ): one to allow quick automated categorization, coupled with a fact-checker to catch any major glitches and inconsistencies.

The quick system is a "heuristic" route, which relies on generalities about the mental world to make snap classifications. So, for example, there is usually a greater degree of perceptual and contextual information in perceived events relative to imagined events. Imagined images are probably sparser in content and richness of detail, so a memory that is full of detail and vividness can be quickly categorized as a good candidate for being a real memory. Even when the situations seem identical, there are subtle differences in memory quality that may be exploited; we can make comparisons in different modalities (audio/visual) to exploit different, but analogous, perceptual and contextual discrepancies.

The second, a "systematic" route, steps through the event in question, using other knowledge bases to appraise whether this labeling is consistent with wider facts (despite my gut feeling, is it really likely I had a pillow fight with Viggo Mortensen last night?) and can step in and reverse decisions made by the quick route.

A.F.

9.5.3. In Real Life

Great examples of source confusion abound. The pioneer neurologist Charcot's patient LeLog was convinced his paralysis was due to his legs being crushed in a traffic accident, yet this injury had never occurred and, in fact, his paralysis had no physical basis. LeLog had mentally rehearsed this situation to the extent that it began to obtain the flavor of reality, leading Charcot to coin the notion that the mind may be parasitized by suggested ideas. A less extreme outcome of source confusion in the healthy mind is unconscious plagiarism.^1,2 This is the consequence of being presented with an idea, usually in a situation in which the ownership may not be explicit or emphasized (brainstorming in a group or hearing a ditty on the radio without any clear sense of the artist), and consequently believing the idea is genuinely your own. Often the individual will rehearse and revisit the idea, and this can demolish its association with an external source or speaker. These errors can lead to merry legal escapades, especially as the accused will be unwilling to back down even in the face of incontrovertible evidence, due to the certainty we have in our own memory. Even Mark Twain, that most individual and independent-minded writer, fell foul of this.³ The same effect may lead to rather less costly squabbles, as evidenced by studies that show identical twins can dispute the possession of certain memories4; the degree of shared existence and confidences in these situations can lead to the real identity of memory protagonists being blurred.

When we turn to the abnormal functioning of the memory system, we are faced with a far more extreme example, that of patients who display confabulations.⁵ These individuals will give fanciful, false responses to questions in totally good faith, mixing details from films, current affairs, or their distant past into statements about their current activities. These individuals can be otherwise functioning fairly normally, and rationally intact, even embarrassed by inconsistencies in the memories they express, but will insist that this is what their minds are offering them. Often information that has been recently presented will be regurgitated as distinctive personal experience, the source dislocated from the item itself.

The reason that we, unlike these patients, rarely produce phantoms of this magnitude is believed to be due to a stellar monitoring and assessment system distributed within the frontal lobes of the brain. It sifts through mental items and labels them correctly as fantasy, fact, or nonsense or warns us that we do not have enough certainty to say either way. We may occasionally forget whether we were intending to turn the oven off or actually did so, but it is rare indeed that we will find ourselves confusing an intention to complete an information-rich task (say, going to visit a relative) with actually having done so.

These systems seem to be at fault within these confabulators, which, in combination with deep memory deficits, allows the creative elements of the mind to weave stories out of piecemeal elements. Confabulations seem to require damage to the two systems together: a severe problem with memory coupled with the lifting of the monitoring systems that prevent flights of fancy and other intact but irrelevant memories being crowned with the status of authenticity.

(

We should also note that, as with many memory dysfunctions, there are likely multiple kinds of confabulation. In particular, damage to the posterior orbitofrontal cortex, a structure in the anterior limbic system (the limbic system is implicated, in part, in memory. See [Hack #7] for more), is argued to cause insistent confabulation by a rather unusual route, namely damage to a motivational system.⁶ The idea is that memories are normally given markers that signify whether the information "pertains to now," but damage to the brain region warps this mechanism so all memories are tagged this way. Any memory brought into consciousness is accompanied by a deep subjective feeling of relevance that is normally afforded to only truly relevant information.

9.5.4. End Notes

1. Stark, L. J., Perfect, T. J., & Newstead, S. (2004). When elaboration leads to appropriation: Unconscious plagiarism in a creative task. Memory (in press).

2. Applied info about plagiarismhas a cognitive bent but contains lots of practical tips for teacherscan be found at http://www.psychologicalscience.org/teaching/tips/tips_0403.html.

3. Mark Twain anecdote delivered at the dinner given by the publishers of The Atlantic Monthly to Oliver Wendell Holmes, in honor of his 70th birthday, August 29, 1879 (http://www.search-engine-lists.com/marktwain/unconscious-plagiarism.html).

4. Sheen, M., Kemp, S., & Rubin, D. (2001). Twins dispute memory ownership: a new false memory phenomenon. Memory & Cognition, 29(6), 779-788.

5. See "Soul In A Bucket," a chapter of Paul Broks' Into the Silent Land (London: Atlantic Books, 2003), which features a patient who confabulates and an eloquent summary of the features of the condition.

6. Schnider,A. (2003). Spontaneous confabulation and the adaptation of thought to ongoing reality. NatureReviews Neuroscience, 4(8), 662-671 .

Alex Fradera