advanced strategies

Memorizing the Geological Time Scale

In the following case study, I explore in depth the issue of learning the geological time scale — names, dates, and defining events. The emphasis is on developing mnemonics, of course, but an important part of the discussion concerns when and when not to use mnemonics, and how to decide.


The Geological Time Scale

Phanerozoic Eon 542 mya—present

  Cenozoic Era 65 mya—present

    Neogene Period 23 mya—present

Holocene Epoch 8000 ya—present

Pleistocene Epoch 1.8 mya—8000ya

Pliocene Epoch 5.3 mya—1.8 mya

Miocene Epoch 23 mya—5.3 mya

   Paleogene Period 65 mya—23 mya

Oligocene Epoch 34 mya—23 mya

Eocene Epoch 56 mya—34 mya

Paleocene Epoch 65 mya—56 mya

  Mesozoic Era 250 mya—65 mya

    Cretaceous Period 145 mya—65 mya

    Jurassic Period 200 mya—145 mya

    Triassic Period 250 mya—200 mya

  Paleozoic Era 542 mya—250 mya

    Permian Period 300 mya—250 mya

    Carboniferous Period 360 mya—300 mya

    Devonian Period 416mya—360 mya

    Silurian Period 444 mya—416 mya

    Ordovician Period 488 mya—444 mya

    Cambrian Period 542mya—488 mya

Precambrian 4560 mya—542 mya

 Proterozoic Eon 2500 mya—542 mya

 Archean Eon 3800 mya—2500 mya

 Hadean Eon 4560 mya—3800 mya


How do we set about learning all this? Let’s look at our possible strategies.

Memorizing new words, lists and dates

Acronyms

A common trick to help remember the geological time scale is to use a first-letter acronym, such as the classic:

Camels Often Sit Down Carefully; Perhaps Their Joints Creak? Persistent Early Oiling Might Prevent Permanent Rheumatism.

(This begins with the Cambrian Period and moves forward in time; note that in this traditional mnemonic the Holocene Epoch is here thought of by its older name of “Recent Epoch”.)

What’s the problem with this, as a way of remembering the geological scale?

It assumes we already know the names.

The principal (and often, only) purpose of an acronym is to remind you of the order of items that you already know.

A common problem with acronyms (first-letter by definition) is that there are often repeats of initials, causing confusion. A more useful strategy (though far more difficult) might be to use the first two or preferably three letters of the words. This not only distinguishes more clearly between items, but also provides a much better cue for items that are not hugely familiar. For example, here’s one I came up with for the geological time-scale:

Hollow Pleadings Plight Miosis;

Olive Eons Pall Creation; (or Olive Eons Palm Credulous, for a slight rhyme)

Juries Trick Perplexed Carousers;

Devils Silence Ordered Campers.

Because it is extremely difficult to make a meaningful sentence with these restraints (largely because of rare combinations such as Eo- and Mio- and to a lesser extent, Pli, Oli, and Jur), I have used rhythm to group it into a verse. There’s a slight rhyme, but it’s amazing how much power rhythm has to facilitate memory on its own.

It is easier, of course, to construct a sentence with these items if you are allowed to include a few “insignificant” words (i.e., not nouns or verbs) to hold them all together. Here’s a possible sentence, this time starting from the oldest and moving forward to the most recent:

Campers Order Silver Devils to Carry Persons Tricking Jurisprudent Cretins in Palmy Eons of Olive Milk and Pliant Pleadings for Holidays

The problem with both this and the “verse” is that they are too long, given their difficulty, to be readily memorable. The answer to this is organization, and later we’ll discuss how to use organization to reduce the mnemonic burden. But first, let’s deal with another problem.

Although the use of three-letter acronyms lessens the need for such deep familiarity with the items to be learned, you do still need to know the items. With names as strange as the ones used in the geological time-scale, the best strategy is probably the keyword mnemonic (or at least a simplified version).

Looking for meaning

But let’s start by considering the origin of the names. If they’re meaningful, if there is a logic to the naming that we can follow, our task will be made incomparably easier.

Unfortunately, in this case there’s not a lot of logic to the naming. Some of the periods are named after geographical areas where rocks from this period are common, or where they were first found — these are probably the easiest to learn. The epochs in particular, however, are problematic, as they are very similar, being based on ancient Greek (in which few students are now trained), and, most importantly of all, being essentially meaningless.

Let’s look at them in detail. The common cene ending comes from the Greek for new (ceno).

  • Holocene is from holos meaning entire
  • Pleistocene is from pleistos meaning most
  • Pliocene is from pleion meaning more
  • Miocene is from meion meaning less
  • Oligocene is from oligos meaning little, few
  • Eocene is from eos meaning dawn
  • Paleocene is from palaois meaning old

So we have

  • Holocene: entire new
  • Pleistocene: most new
  • Pliocene: more new
  • Miocene: less new
  • Oligocene: little new
  • Eocene: dawn new
  • Paleocene: old new

You could find this helpful (remember that we’re moving backward in time, so that the Holocene is indeed the newest of these, and the Paleocene is the oldest), but the naming is really too arbitrary and meaningless to be of great help.

Better to come up with associations that have more meaning, even if that meaning is imposed by you. Here’s some words you could use:

  • Holocene: holy; hollow; hologram; holly
  • Pleistocene: plasticine; plastic
  • Pliocene: pliable; pliant; pliers
  • Miocene: my; milo; myopic
  • Oligocene: oligarchy; olive; oliphaunt (! Notice that the words don’t have to be familiar to the whole world, even the dictionary-makers; the important thing is that they have significance to you)
  • Eocene: eon; enzyme; obscene (note that it is not necessary for the word to begin with the same letter(s) — a particularly difficult task in this instance; what’s important is whether the word will serve as a good link for you)
  • Paleocene: palace; palatial; paleolithic

To tie your chosen word to the word to be learned, you must form an association (that’s why it’s so important to choose a word that’s good for you — associations are very personal). For example, you could say:

  • Holograms are very recent (the Holocene is the most recent epoch)
  • Glaciers are plastic or My glaciers are made of plasticine (the Pleistocene was the time of the “Great Ice Age”)
  • The pliant Americas joined together or Pliable hominids arose (Hominidae began in the Pliocene, and North and South America joined up)
  • Mild weather saw Africa collide with Asia (the Miocene was warmer than the preceding epoch; during this time Africa finally connected to Eurasia)
  • Elephants become oligarchs! (during the Oligocene mammals became the dominant vertebrates)
  • Continents obscenely separate (Laurasia, the northern supercontinent, began to break up at the beginning of the Eocene; Gondwanaland, the southern supercontinent, continued its breakup)
  • Pale from the disaster, we pull ourselves together (the Paleocene marks the beginning of a new era, after the K-T boundary event (thought by many to be an asteroid impact) in which the dinosaurs and so much other life died)

Now this is not, of course, in strict accordance with the keyword method. According to this method, we should choose a word as phonetically similar to the word-to-be-learned as possible, and as concrete as possible, and then form a visual image connecting the two. While this is fine with learning a different language (the most common use for the keyword method, and the one for which it was originally designed), it is clearly very difficult to create an image for something as abstract and difficult to visualize as a period of time.

It’s also often difficult to find keywords that are both phonetically similar and concrete. We must improvise as best we may. What you need to bear in mind is that you are searching for an association that will stick in your mind, and link the unfamiliar (the information you are learning) to the familiar (information already well established in your mind).

With this in mind, look again at the suggested associations. This time, think in terms of whether you can make a picture in your mind.Holocene mnemonic image

Instead of “Holograms are very recent”, you might want to form an image of someone falling into a hole (tying the Holocene to the “Age of Humans”).

 

Glaciers made of plasticine might stand.Pleistocene mnemonic image

 

 

 

 

 

Pliocene mnemonic imageIf you can visualize very limber (perhaps in distorted postures) ape-like humans, Pliable hominids might be satisfactory, or you may need to fall back on the pliers — perhaps an image of pliers bringing North and South America together.

 

 

Miocene mnemonic imageMild weather isn’t terribly imageable; you might like to imagine milk pouring from the joint where Africa and Eurasia have collided.

 

 

Oligocene mnemonic imageOligarchs is likewise difficult, but you could visualize elephants under olive trees, eating the olives.

 

 

 

 

Eocene mnemonic imageAnd now of course, we come to the most difficult — the Eocene. Here’s a thought, for those brought up with Winnie the Pooh. If you have a clear picture of Eeyore, you could use him in this image. Perhaps Eeyore is standing on one part of the separating Laurasia (looking appropriately disconsolate).

 

 

Paleocene mnemonic image

The Paleocene might best be associated with a palace, if we’re looking for something imageable — perhaps dinosaurs sheltering in a palace as the asteroid comes down and destroys it.

 

You see from this that the demands of visual associations are often quite different from those of verbal associations. Both are effective. Whether you use verbal or visual associations should depend not only on your personal preference (some people find one easier, and some the other), but also on what the material best affords — that is, what is easiest, what comes more readily to mind, and also, which association will be less easily forgotten.

But mnemonics only take you so far. While very useful for learning new words, and for learning lists, they are not a good basis for developing an understanding of a subject — and unlike the situation of learning a language, a scientific topic definitely requires a more holistic approach. Mnemonics here are very much an adjunct strategy, not a complete solution. So before using mnemonics to fix specific hard-to-remember details in my brain, I would begin by organizing the information to be learned, with the goal of cutting it into meaningful chunks.

 

Excerpted from Mnemonics for Study

 

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Story mnemonic

The story method (sometimes called the sentence mnemonic) is the most easily learned list-mnemonic strategy, although it is not as widely known as the other simple methods we’ve talked about so far.

As its name suggests, the story method involves linking words to be learned in a story. While this is most obviously useful for learning actual lists, it can also be used for remembering the main points of a passage. In such a case, you need to reduce each point to a single word, which hopefully has the power to recall the whole point.

Let’s look at an example. First, an easy one — a list:

Vegetable Instrument College Carrot Nail Fence Basin Merchant Scale Goat

This can be transformed into:

A VEGETABLE can be a useful INSTRUMENT for a COLLEGE student. A CARROT can be a NAIL for your FENCE or BASIN. But a MERCHANT would SCALE that fence and feed the carrot to a GOAT.

But let’s face it , this is not a very probable list of words for you to memorize. The example is taken (with some modification) from a laboratory experiment1, and the few tests of the story mnemonic that there have been have tended to involve such lists of unrelated words. But learning lists of unrelated words is not something we need to do very often. And generally, if we do have lists of words to learn — say, the names of the elements in the periodic table — they’re going to be too technical to lend themselves readily to creating a story.

Even if the words themselves are not particularly technical, the nature of them is not likely to lend itself to a narrative. Let me show you what I mean. Consider the taxonomy of living things:

Kingdom

Phylum

Class

Order

Family

Genus

Species

Here’s an attempt at a story:

In the KINGDOM, PHYLUM is a matter of CLASS, but ORDER is a matter for FAMILY, and GENIUS lies in SPECIES.

The trouble with this is not the re-coding of genus to genius; the trouble is, it doesn’t make a lot of sense. It’s a sentence, but not a story — there’s no narrative. Humans think in stories. We find them easy to remember because they fit in with how we think. It follows then that the more effective story mnemonics will actually tell a story. To do that, we’re going to have to transform our technical words into more common words.

King Phillip went to the classroom to order the family genius to specifically name the individual who had stolen the taxi.

The last part of this is of course unnecessary — you could finish it after individual if you wished. But an important thing to remember is that it’s not about brevity. It’s about memorability. And memorability is not as much affected by amount to remember, as it is by the details of what is being remembered. So meaningfulness is really important. Adding that little detail about stealing the taxi adds meaningfulness (and also underlines what this mnemonic is about: taxonomy).

Here’s a longer example. Remember our hard-to-remember cranial nerves? This story was mentioned in a 1973 Psychology Today article by the eminent psychologist G.H. Bower2:

At the oil factory the optician looked for the occupant of the truck. He was searching because three gems had been abducted by a man who was hiding his face and ears. A glossy photograph had been taken of him, but it was too vague to use. He appeared to be spineless and hypocritical.

Here it is again with the nerves shown for comparison:

At the oil factory (olfactory) the optician (optic) looked for the occupant (oculomotor) of the truck (trochlear). He was searching because three gems (trigeminal) had been abducted (abducens) by a man who was hiding his face (facial) and ears (auditory). A glossy photograph (glossopharyngeal) had been taken of him, but it was too vague (vagus) to use. He appeared to be spineless (spinal accessory) and hypocritical (hypoglossal).

Notice how, with these technical words, they have been transformed into more familiar words — this is what I meant by saying the keyword method is a vital part of all these list-mnemonics.

 

Excerpted from Mnemonics for Study

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Coding mnemonics

Most people find numbers — phone numbers, personal identification numbers, dates, and so on — more difficult to remember than words. That is, of course, why businesses try to get phone numbers that correspond to some relevant word. The system whereby this is possible — the linking of certain letters to the different digits on a telephone calling pad —is a kind of coding mnemonic. Basically, coding mnemonics are systems that transform numbers into words.

Because words are much easier for most of us to remember, this is a good way to remember numbers, but it’s not the only one. If you have a facility for numbers, or an existing store of memorized numbers (dates, baseball scores, running times, whatever), you can use those memorized numbers or your understanding of mathematical patterns to remember new numbers. In one well-known experiment1, for example, the subject was able (after 250 hours of practice!) to recall up to 82 digits after hearing them at the rate of one digit a second. This subject was a runner, and used his knowledge of record times to make the digit strings more memorable.

The difficulty with a coding system is that you can’t use it effectively until you have fluently memorized the codes, to the extent that the linked letter (if encoding) or digit (if decoding) comes automatically to mind. This requirement makes this sort of mnemonic the costliest of all the mnemonics — that is, it takes the most time and effort to master.

Here is the best-known digit-letter code — it’s important to note the system is based on sound rather than actual letters, so various similar sounding letters are regarded as equivalent:


0 = s, z, soft c (zero starts with a s sound)

1 = t, d, th (there’s 1 downstroke in t)

2 = n (2 downstrokes in n)

3 = m (3 downstrokes in m)

4 = r (r is the last letter of four)

5 = l (l is 50 in Roman numbers)

6 = sh, ch, j, soft g (six has a sort of sh sound)

7 = k, q, hard g, hard c (number 7 is embedded in k)

8 = f, v (both 8 and f have two loops)

9 = p, b (9 is p the wrong way round)


Practical uses for coding mnemonics

In the study situation, there is quite a lot of numerical information that you might need or be interested in learning. Historical dates; mathematical formulae; geographical facts. Let’s look at how we can combine three different mnemonics to remember the lengths of the ten longest rivers (in miles):

  1. Nile (4140 miles)
  2. Amazon (3990 miles)
  3. Yangtse (3960 miles)
  4. Yenisei-Angara (3445 miles)
  5. Ob-Irtysh (3360 miles)
  6. Hwang Ho (3005 miles)
  7. Zaire/Congo (2900 miles)
  8. Amur (2800 miles)
  9. Mekong (2795 miles)
  10. Lena (2730 miles)

First, let’s use the coding mnemonic to convert the lengths:

  1. Nile 4140 = r-t-r-s = rotors, raiders, readers
  2. Amazon 3990 = m-p-p-s = my pipes
  3. Yangtse 3960 = m-p-sh-s = impish ass
  4. Yenisei-Angara 3445 = m-r-r-f = more or few, more rev
  5. Ob-Irtysh 3360 = m-m-sh-s = mommy shoes
  6. Hwang Ho 3005 = m-s-s-f = mass shave, miss safe
  7. Zaire/Congo 2900 = n-p-s-s = any passes
  8. Amur 2800 = n-f-s-s = no fusses
  9. Mekong 2795 = n-k-p-f = neck puff
  10. Lena 2730 = n-k-m-s = hen games

They’re not brilliant, I know. Sometimes numbers will fall nicely into meaningful words, but more often than not they won’t. Still, you’ll be surprised how much these rather weird phrases help.

Now we need to use the keyword mnemonic to turn the names of the rivers into something concrete and familiar.

Nile — nail

Yangtse — ant sea (a sea of ants)

Yenisei-Angara — nice anchor (nice is not concrete, but you can attach it by always thinking nice anchor when visualizing it)

Ob-Irtysh — (observe the) yurt

Hwang Ho — hanging (image of a noose hanging from a gallows)

Zaire/Congo — stair (not using Congo because of its similarity to Mekong)

Amur — a mule

Mekong — King Kong

Lena — lion

You’ll notice I didn’t give a keyword for Amazon; I felt the female Amazon would provide an adequate image.

Now we can use the pegword mnemonic to provide our ordered list. So we tie our keywords to the pegwords to produce the following images:

  1. a nail in a bun
  2. an Amazon with one big shoe
  3. a sea of ants around a tree
  4. an anchored door
  5. someone watching a yurt with a beehive hanging from its pole
  6. an axe among sticks next to the gallows
  7. stairway to heaven
  8. a mule nudging a gate
  9. King Kong drinking wine
  10. a lion ripping apart a hen

Once you’ve worked on visualizing these images and got them well down, you can then connect the images to your sentences. Don’t worry if your images aren’t as clear as you think they should be; I rely equally on the words as much as the images — but it helps to visualize as much as you can while thinking on the words.

Now you’ve got these word-images (and it really does take very little practice), you can stick the coded phrases on.

  1. a nail in a bun: rotors (helicopter blades) trying to lift the nailed bun
  2. an Amazon with one big shoe: tripping over her big shoe, she drops her blowpipes: My pipes! she cries
  3. a sea of ants around a tree: an impish ass (donkey) grins as he flicks ants at the tree
  4. an anchored door: the door strains to move against its anchor; I shout: More rev!
  5. someone watching a yurt with a beehive hanging from its pole: the observer is wearing mommy shoes
  6. an axe among sticks next to the gallows: a mass of people lining up to be shaved by the axe (mass shave)
  7. stairway to heaven: “any passes?” I ask anxiously
  8. a mule nudging a gate: going through easily; “no fusses
  9. King Kong drinking wine: big neck puff around his neck
  10. a lion ripping apart a hen: hen games!

It all sounds very strained and unnecessarily complicated if you simply read all this! You absolutely cannot appreciate this method until you try it. It really is much simpler than it appears (although still not a simple strategy). However, it is vital that you build up the strategy step by step. In this case, for example, you must be fully confident of the standard 1-10 pegwords (1 is a bun, etc) first; then you fix the rivers to the pegwords firmly; and finally you attach the coded phrases.

 

Excerpted from Mnemonics for Study

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Achieving flow

I’ve recently had a couple of thoughts about flow — that mental state when you lose all sense of time and whatever you’re doing (work, sport, art, whatever) seems to flow with almost magical ease. I’ve mentioned flow a couple of times more or less in passing, but today I want to have a deeper look, because learning (and perhaps especially that rewiring I was talking about in my last post) is most easily achieved if we can achieve "flow" (also known as being ‘in the zone’).

Let’s start with some background.

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Event boundaries and working memory capacity

In a recent news report, I talked about how walking through doorways creates event boundaries, requiring us to update our awareness of current events and making information about the previous location less available. I commented that we should be aware of the consequences of event boundaries for our memory, and how these contextual factors are important elements of our filing system. I want to talk a bit more about that.

References: 

Culham, J. 2001. The brain as film director. Trends in Cognitive Sciences, 5 (9), 376-377.

Kurby, C. a, & Zacks, J. M. (2008). Segmentation in the perception and memory of events. Trends in cognitive sciences, 12(2), 72-9. doi:10.1016/j.tics.2007.11.004

Speer, N. K., Zacks, J. M., & Reynolds, J. R. (2007). Human Brain Activity Time-Locked to Narrative Event Boundaries. Psychological Science, 18(5), 449–455. doi:10.1111/j.1467-9280.2007.01920.x

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Subliminal & sleep learning

Subliminal learning achieved notoriety back in 1957, when James Vicary claimed moviegoers could be induced to buy popcorn and Coca-Cola through the use of messages that flashed on the screen too quickly to be seen. The claim was later shown to be false, but though the idea that people can be brainwashed by the use of such techniques has been disproven (there was quite a bit of hysteria about the notion at the time), that doesn’t mean the idea of subliminal learning is crazy.

Ten years ago, researchers demonstrated that subliminal messages do indeed affect human cognition — and showed the limits of that influence [1]. The study demonstrated that, to have an effect on a person’s decision, the subliminal message had to be received very very soon before that decision (a tenth of a second or less), and the person had to be forced to make the decision very quickly. Moreover, there was no memory trace detectable, indicating no permanent record was stored in memory.

But even such brief, low-level learning seems to require some level of attention. A study [2] found that subliminal learning doesn’t occur if the subliminal stimuli are presented during what has been termed an "attentional blink" You may recall when I’ve discussed multi-tasking, I’ve said that we can’t do two things at the same time — that tasks have to "queue" for attention. When a bottleneck occurs in the system, this attentional "blink" occurs.

But low-level sensory processing, which is an automatic process, isn’t affected by the attentional blink, so the finding that subliminal learning is affected by the blink indicates that subliminal stimuli require some high-level cognitive processing.

This finding has been confirmed by other studies. One such study [3] also has implications for reading. Participants in the study were shown either words or pronounceable nonwords and asked to perform either a lexical task (to identify whether the word they saw was a real word or a nonsense word) or a pronunciation task on the words. Unbeknownst to the participants however, they had been first presented with a subliminal word that either matched or didn't match the target word. People performed the tasks faster when the subliminal word was identical to the target word. However (and this is the interesting bit), the researchers then applied a magnetic pulse (transcranial magnetic stimulation) to the key brain regions of the brain before presenting the subliminal information. By applying TMS to one brain area or the other, they found they could selectively disrupt the subliminal effect for either the lexical or pronunciation task. In other words, it seems that, even when the stimulus is subliminal, the brain takes into account the conscious task instructions. Our expectations shape our processing of subliminal stimuli.

Another study [4] suggests that motivation is important, and also, perhaps, that some stimuli are more suitable than others. The study found that thirsty people could be encouraged to drink more, and also pay more for their drink, after being exposed to subliminal smiling faces. Subliminal frowning faces had the opposite effect. However, how much, and whether, the faces had an effect on drinking, depended on the person’s thirst. Those who weren’t thirsty weren’t affected at all. Smiles and frowns are of course stimuli to which we are very responsive.

So clearly, although it is possible to be unconsciously affected by stimuli that can’t be consciously detected, the effect is both small and fleeting. However, that doesn’t mean more long-term effects can’t be experienced as a result of information we’re not conscious of.

Psychologists make a distinction between explicit memory and implicit memory. Explicit memory is what you’re using when you remember or recognize something — it’s what we tend to think of as "memory". Implicit memory, on the other hand, is a concept that reflects the fact that sometimes people act in ways that are clearly affected by earlier experiences they have had, even though they are not consciously recalling such experiences.

Another study [5] that used erotic images (because, like smiling and frowning faces, these are particularly potent stimuli, making it easy to see a response) found that when your eyes are presented with erotic images in a way that keeps you from becoming aware of them, your brain can still detect them — evidenced by the way people respond to the images according to their gender and sexual orientation.

The study is more evidence that the brain processes more visual information than we are conscious of — which is an important part in the process of determining what we’ll pay attention to. But the researchers believe that the information is probably destroyed at an early stage of processing — in other words, as with subliminal stimuli, there is probably no permanent record of the experience.

Which leads me to sleep learning. This was a big idea when I was young, in the science fiction I read — the idea that you could easily master new languages by being instructed while you were asleep.

Well, the question of whether learning can take place during sleep (and I’m not talking about the consolidation of learning that’s occurred earlier) is one that has been looked at in animal studies. It has been shown that simple forms of learning are indeed possible during sleep. However, the way in which associations are formed is clearly altered even for simple learning, and complex forms of learning do not appear to be possible.[6]

As far as humans are concerned, the evidence is that any learning during sleep must occur during the lightest stage of sleep, when you still have some awareness of the world around you, and that what you are learning must be already familiar (presented previously while you were awake and paying attention) and not requiring any understanding.

All the evidence suggests that, although information can be processed without conscious awareness, there are severe limitations on that information. If you want to "know" something in the proper meaning of the word — be able to recall it, think about it — you need to actively engage with the information. No free lunches, I’m afraid!

But that doesn’t mean unconscious influences don’t have important implications for learning and memory. A paper provided online in the Scientific American Mind Matters blog describes how a single, 15-minute intervention erased almost half the racial achievement gap between African American and white students. And this is entirely consistent with a number of studies showing how our cognitive performance is affected by what we think of ourselves (which is affected by what others think of us).

This article first appeared in the Memory Key Newsletter for March 2007

References: 

  1. Greenwald, A.G., Draine, S.C. & Abrams, R.L. 1996. Three Cognitive Markers of Unconscious Semantic Activation. Science, 273 (5282), 1699-1702.
  2. Seitz, A. et al. 2005. Requirement for High Level Processing in Subliminal Learning. Current Biology, 15, R753-R755, September 20, 2005.
  3. Nakamura, K. et al. 2006. Task-Guided Selection of the Dual Neural Pathways for Reading. Neuron, 52, 557-564.
  4. Winkielman, P. 2005. Paper presented at the American Psychological Society annual convention in Los Angeles, May 26-29. Press release
  5. Jiang, Y. et al. 2006. A gender- and sexual orientation-dependent spatial attentional effect of invisible images. PNAS, 103 (45), 17048-17052.
  6. Coenen, A.M. & Drinkenburg, W.H. 2002. Animal models for information processing during sleep. International Journal of Psychophysiology, 46(3), 163-175.

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Photographic Memory

Does photographic memory exist?

"Photographic" or eidetic memory is said to occur in some 8% of children, but almost all of these grow out of it. The phenomenon is extremely rare in adults, and indeed the very existence of photographic memory is still somewhat contentious. However, it may be that particular brain abnormalities can lead to ways of processing information that are dramatically different from the normal (see the case of Kim Peek).

Is a photographic memory desirable?

It is generally assumed that at any rate such a memory would be a great thing to have. I am by no means sure, however, that such is the case.

Let us dwell for a moment on Shereshevskii, a remarkable memorist made famous in a book by A.R. Luria. Although Shereshevskii did not have a “photographic” memory as such, he had a formidable ability to rapidly and easily commit vast amounts of information to memory, due to his amazing capacity for synaesthesia (the association of one sensory modality with another, so, e.g., you might “see” a tone as green) and ability to create visual images.

However, while advantageous in many regards, this ability did have a quite serious downside. Irrelevant details would tend to be included in his memory, and these would stand in the way of his subsequent recall. The confusion of so many conflicting images and sensory details would also often impede his understanding. He also had great difficulty in forgetting, and as time went on had increasing difficulty with the many items in his memory he did not wish to recall (although he did in fact hit on a solution to this: he imagined the information written on a blackboard, and pictured himself erasing it!)

Interestingly, some time ago, I received an email from a reader who knew an adolescent troubled with a “photographic memory” — she had a great deal of difficulty understanding what she was reading.

My point is that simply being a database, like a computer, is not sufficient in itself. Memory to be useful must be able to be used! And the most effective memory strategies are those that facilitate the use of memory, not simply its storage.

On this note, I would like to quote Mary Carruthers, who has written extensively about the medieval “arts of memory”. Carruthers argues convincingly that the idea that “the good of an art of memory is to remember things in order to regurgitate them by rote later on” is a misconception. On the contrary, “the orator’s “art of memory” was not in practice designed to let him reiterate exactly in every detail a composition he had previously fabricated. … [but] an art of invention, an art that made it possible for a person to … respond to interruptions and questions, or to dilate upon the ideas that momentarily occurred to him without becoming hopelessly distracted, or losing his place in the scheme of his basic speech.”

Similarly, the art of memory practiced by medieval monks involved “the making of mental images for the mind to work with as a fundamental procedure of human thinking.” The technique was designed not simply to provide “immediate access to whatever piece of stored material one may want, [but] also provides the means to construct any number of cross-referencing, associational links among the elements.”

References: 

  • Carruthers, M. 1998. The Craft of Thought: Meditation, Rhetoric. and the Making of Images. 400-1200. Cambridge: Cambridge University Press.
  • Ericsson, K.A. (1985). Memory skill. Canadian Journal of Psychology, 39, 188-231.
  • Higbee, Kenneth L. Your memory. How it works and how to improve it. NY: Simon & Schuster, Inc., 1988.
  • Luria, A.R. 1968. The Mind of a Mnemonist. New York: Basic Books.
  • Thompson, C. P., Cowan, T.M. & Frieman, J. Memory search by a memorist. Hillsdale, NJ: Lawrence Erlbaum Ass., 1993.

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