8For a review of the literature on the capacity of human memory, refer to: Yadin Dudai. “How big is human memory, or on being just useful enough.” Learning and Memory 3 (5) (1997): 341–365.
9Hermann Ebbinghaus. Über das Gedächtnis: Untersuchungen zur experimentellen Psychologie. Leipzig: Duncker & Humblot, 1885. (Memory: A Contribution to Experimental Psychology, Tr. Henry A. Ruger & Clara E. Bussenius. New York: Teachers College, Columbia University, 1913.)
10For a description of the results obtained with many subjects, see Chapter 5 of the book: Frederic Bartlett. Remembering. Cambridge: Cambridge University Press, 1932.
Chapter 7 describes similar results obtained using several other stories. For a description of the contrasting views of Ebbinghaus and Bartlett, see Chapter 5 of: Alan Baddeley, Michael Eysenck, and Michael Anderson. Memory. New York: Psychology Press, 2009.
11Elizabeth Loftus and John Palmer. “Reconstruction of automobile destruction: An example of interaction between language and memory.” Journal of Verbal Learning and Verbal Behavior 13 (1974): 585–589.
12For more details, see: Elizabeth Loftus. “Our changeable memories: Legal and practical implications.” Nature Reviews Neuroscience 4 (2003): 231–234.
13Testimony by Cotton, Thompson, and the detective can be found on video: www.youtube.com/watch?v=-2oDRfj0vME.
14Elizabeth Loftus describes the case of Steve Titus, another man identified incorrectly as a rapist. The interesting detail here is that the victim said, “That one’s the closest” at the initial lineup and during the trial changed her line to “I’m absolutely positive that’s the man.” Titus was set free after a subsequent investigation uncovered the true culprit.
15The tragic story of Jennifer Thompson and Ronald Cotton had, surprisingly, a happy ending. They are close collaborators who advocate for change in eyewitness-related practice and wrongful conviction legislation, and even wrote a book on the subject.
16The results are described in: Thomas Landauer. “How much do people remember? Some estimates of the quantity of learned information in longterm memory.” Cognitive Science 10 (1986): 477–493.
17For a review of different estimates of memory capacity see: Yadin Dudai. “How big is human memory, or On being just useful enough.” Learning and Memory 3(5) (1997): 341–365.
18Refer to Chapter 12 of Borges and Memory for a more comprehensive discussion of the topic.
19To arrive at this number, I simply took the number of characters in this chapter and divided it by the number of words. Similar estimates can be easily found on the internet.
20Considering that an average person (or an average text sample) uses no more than 20,000 words (see Dudai, 1997), which (as 215 is 32,768) can be represented with 15 bits, we obtain 15 × 3 = 45 bps if we assume a reading rate of three words per second.
21See Table 3 in Dudai (1997).
22Again, as we noticed in the case of the visual artists described in Chapter 3, there is a very interesting intersection between art—in this case the art of magic—and neuroscience. Neuroscientists have much to learn from magicians, who for the last 2,000 years have mastered subjects of great relevance to neuroscience such as attention, decision-making, memory, etc. For a recent essay on this topic, see: Rodrigo Quian Quiroga. “Magic and cognitive neuroscience.” Current Biology 26 (2016): R387–R407.
23Other ways of generating tension include the use of rhythm and volume. A monotonous rhythm that is suddenly interrupted cries for its resumption; a rhythm that accelerates, decelerates, or plays progressively louder cries out for change. These tricks are widely used in contemporary dance music, which lacks classical structure in melody and harmony.
24This is the basic idea behind what is known as Bayesian inference, a principle widely used in neuroscience.
Chapter 5
1So much for actual events. However, as with any good legend, Quintilian on the one hand, and Cicero on the other, spun a much more interesting tale with a peculiar mythological background. According to this version, the banquet’s host was a nobleman called Scopas, who was celebrating having won a boxing match. Simonides was hired to declaim a poem in Scopas’s honor, in which Simonides, as was customary, included legendary figures. In particular, Simonides mentioned in his poem the brothers Castor and Pollux, siblings of Helen of Troy, who were considered the patron saints of both athletes and sailors. It came to pass that Scopas maliciously decided to pay Simonides only half of the agreed-upon sum for his poem, telling him he should charge the rest to Castor and Pollux. According to legend, it was Castor and Pollux who came to pay Simonides his due and called him to the door just before the roof came crashing down.
2When I tried to remember the list of words a few hours after I first wrote them, I found that I remembered all of them except the lamp, which, after all, was not so conspicuous on the pedestrian crossing. To enhance my memory of the lamp, I added detail, imagining that it turned on and off with each passing pedestrian. Some ten days after creating this association between these words and places, and having given it no thought in the meantime, I was able to remember all the words except the first. The problem that time was that I had put the bread at the corner, which was the first place I visited in my stroll. However, it was so obvious that this was the first spot that I failed to take the time to form a specific image of the corner and the loaf of bread resting on it. This highlights the need to use vivid and specific images, both of the places and of the words you wish to remember.
3A study carried out in the 1970s performed this very comparison by giving two groups of subjects five lists of twenty words each, and asking one group to memorize the lists using the method of loci and the other group to learn them some other way. The difference is striking: the first group remembered 72 percent of the words on average, while the second averaged only 28 percent. For more details, see: Gordon H. Bower. “How to . . . uh . . . remember!” Psychology Today 7 (5) (1973): 63–70.
An earlier study had shown that the method of loci enabled subjects to remember more than 95 percent of a list of between forty and fifty words after looking at them only once. For more details, see: John Ross and Kerry Ann Lawrence. “Some observations of memory artifice.” Psychonomic Science 13 (2) (1968): 107–108.
These and other quantitative studies of the method of loci are described in Chapter 16 of: Alan Baddeley, Michael W. Eysenck, and Michael C. Anderson. Memory. New York: Psychology Press, 2009.
4There are various techniques to associate numbers with images. Some are described in several books by Dominic O’Brien, as well as in: Joshua Foer. Moonwalking with Einstein: The Art and Science of Remembering Everything. New York: Penguin, 2012.
5The invention of paper, in the year 105 of the current era, is attributed to Ts’ai Lun, an official in the royal court of the Han dynasty in China. However, it took this discovery more than a millennium to be known in the West. The manufacture of paper expanded to the Muslim world after the battle between the Arab caliphate and the Chinese empire at Talas in 751. During this battle, the Arabs captured Chinese prisoners, who taught them to make paper in exchange for freedom. But the secrets of paper manufacturing were jealously guarded by the Chinese and Arabs alike and were unknown in Europe until the twelfth century, when the Spanish retook the southern part of the Iberian Peninsula from the Arabs. Before paper, people wrote on papyrus (which had to be imported from Egypt and was thus very expensive) or on the even dearer parchment (made from animal skin). In antiquity, especially in ancient Greece, wax tablets—slabs of wood with wax spread on one side—were also used. Several writing techniques were indeed available in ancient times, but they were onerous and expensive, and thus of limited use; hence the relevance of exercising memory.
6Along with the anonymous Ad herenium, these are the most important works on memory and mnemonics to come to us from antiquity.
7References to the remarkable powers of memory of these men can be found in the treatises by Cicero and Quintilian and in Pliny the Elder’s Natura
lis historia.
8Cicero, De oratore II, LXXXVIII, 360.
9Historian Frances Yates attributes the loss of the Greek-initiated tradition of mnemonics to the difficulties of a barbarous age, where it was dangerous even to assemble to listen to someone speak. Moreover, the main reference works on mnemonics were lost, and medieval studies of memory, mainly Aquinas’s, were based on texts either incomplete or misinterpreted. This was particularly true in the case of Quintilian’s Institutio oratoria, which offered the most concrete description of the method of loci as used by orators in Greece and Rome, and whose complete text was found as late as 1416, in the library of the Abbey of St. Gall in present-day Switzerland. In these paragraphs I follow the arguments set forth by Frances Yates, who drafted a fascinating historical description of the use of mnemonics from antiquity to the Renaissance in her 1966 book The Art of Memory (London: Routledge).
10Peter of Ravenna, Fornix, ed. of Venice, 1491, quoted in Yates, The Art of Memory, 113.
11Fragment of a letter from Vigilius Zuychemus to Erasmus of Rotterdam, quoted in Yates, The Art of Memory, 131. Vigilius was one of the few people to have access to the wooden model, which was never finished or shown to the public. His writings to Erasmus are one of the few concrete proofs of the theater’s existence.
12Giulio Camillo, L’idea dela theatro, Florence and Venice, 1550, quoted in Yates, The Art of Memory, 138.
13Roberto Belarmino, a cardinal inquisitor and a member of the tribunal that sentenced Giordano Bruno to be burned at the stake, was very involved years later in the famous trial of Galileo Galilei for heresy due to Galileo’s support of Copernicus’s heliocentric theory.
14Again, for more details I refer to Frances Yates’s book, in this case to the fifth and final chapter.
15Luria offers a brief and fascinating account of Shereshevskii in his book The Mind of a Mnemonist: A Little Book about a Vast Memory. Cambridge, MA: Harvard University Press, 1987.
16The extraordinary similarity between Funes and Shereshevskii is explored in Chapter 3 of: Rodrigo Quian Quiroga. Borges and Memory. Cambridge, MA: MIT Press, 2011.
17As we saw in the previous chapter, this notion was already present in the ideas of Aristotle and Thomas Aquinas.
18For more details about Kim Peek and other savants, see: Darrold Treffert. Islands of Genius (London: Jessica Kingsley, 2010). Dr. Treffert is a savant specialist who worked with Peek for many years.
Chapter 6
1Estimates based on considerations of anatomy (such as neuron density) and neurophysiology (such as the effective area in which an electrode can register a neuron’s firing) conclude that between 5 percent and 10 percent of neurons whose activity can be recorded are active at a given instant. For more details, see: Gyorgy Buzsáki. “Large-scale recording of neuronal ensembles.” Nature Neuroscience 7 (5) (2004): 446–451.
2The activation of neurons is a very expensive process in metabolic terms. The brain represents about 2 percent of a human body’s mass but uses 20 percent of its energy.
3Part of the difficulty in finding a general treatment or cure for epilepsy stems from the fact that epilepsy is a blanket name historically given to a range of pathologies with different clinical manifestations and gestation mechanisms. A child who lapses for a few seconds into an absence seizure is very different from an adult writhing on the street; a person with a facial tic differs from another who unexpectedly loses muscular firmness and drops to the floor. Another difficulty is that the onset of epileptic seizures tends to be abrupt, which makes it hard to determine, based on electroencephalographic records, just when and why a seizure began. In fact, starting in the 1990s, several labs have devoted their efforts to predicting epileptic seizures, with no success so far. For example, see: Florian Mormann, Ralph Andrzejak, Christian Elger, and Klaus Lehnertz. “Seizure prediction: the long and winding road.” Brain 130 (2) (2007): 314–333.
4Participants in memory championships attempt to memorize the greatest number of cards, numbers, words, names, etc.
5As reported in: Alan Baddeley, Michael W. Eysenck, and Michael C. Anderson. Memory. New York: Psychology Press, 2009, 363.
6A survey carried out in Norway showed that more than 90 percent of respondents thought that it is possible to improve one’s memory, just as one can become stronger by exercising. This belief, however, is incorrect, since the prowess attained by exercising a specific type of memory does not transfer to other types. For more details, see: Svein Magnussen et al. “What people believe about memory.” Memory 14 (2006): 595–613.
For more details about the fact that memory abilities do not transfer, see: A. Owen, A. Hampshire, J. Grahn, R. Stenton, S. Dajani, A. Burns, R. Howard, and C. Ballard. “Putting brain training to the test.” Nature 465 (2010): 775–778.
7A recent study compared the ability of students to remember the names of people they met at a party using different methods. Surprisingly, those who used a visual technique (relating each name to a different thing) recalled fewer names than those who used no method at all. The problem is that the distractions present in a real situation, such as at a party, conspire to hinder an optimal implementation of the method. For more details, see: P. Morris, C. Fritz, L. Jackson, E. Nichol, and E. Roberts. “Strategies for learning proper names: Expanding retrieval practice, meaning and imagery.” Applied Cognitive Psychology 19 (2005): 779–798.
8In the final pages of his 2012 book Moonwalking with Einstein, Joshua Foer mentions that, while the use of mnemonics greatly improved his ability to remember information, one night, as he returned home via the subway after dinner with friends, he realized he had taken his car to the restaurant.
9A study carried out with professors at the University of California, Berkeley, showed that, given their prolific intellectual activity, the professors had much smaller memory and cognitive deficits due to aging compared to other people. For more details, see: Arthur Shimamura, Jane Berry, Jennifer Mangels, Cheryl Rusting, and Paul Jurica. “Memory and cognitive abilities in university professors.” Psychological Science 6 (1995): 271–277.
10Rodrigo Quian Quiroga. Borges and Memory. Cambridge, MA: MIT Press, 2012.
11This estimate was made by Martin Hilbert, communications expert and professor at the University of California, Davis, taking into account the information received through email, television, cell phones, newspapers, radio, etc. For more details, see: Martin Hilbert and P. López. “The world’s technological capacity to store, communicate, and compute information.” Science 332 (6025) (2011): 60–65.
12In The Shallows: What the Internet Is Doing to Our Brains (New York: W. W. Norton, 2010), Nicholas Carr describes how, after using the internet for many years, he finds it almost impossible to focus enough to read a book.
13In Moonwalking with Einstein, Joshua Foer relates how difficult it is to find the most intelligent person in the world. In fact, Google makes it relatively easy to find the oldest, tallest, or (according to some competition result) strongest person. But how do we define who is smartest? IQ provides only a vague idea, and in fact its ability to measure intelligence is quite limited. What is interesting about Foer’s quest is that it led him naturally to search for people with prodigious memory. To aid his search, Foer started to hone his own memory, with the unexpected consequence that he ended up winning a memory championship in the US. His bestseller is an entertaining account of this series of events—in particular, his learning of the method of loci and his interaction with professional mnemonists.
14Among other things, Richard Andersen discovered two areas of the brain (in the posterior parietal cortex, to be precise) whose function is to plan arm and eye movements, respectively. For many years, Richard has studied how visual information leads to movement execution—for example, when lifting a glass from a table. See, for example: Hans Scherberger, Rodrigo Quian Quiroga, and Richard Andersen. “Coding of movement intentions.” In: Rodrigo Quian Quiroga and Stefano Panzeri, eds. Principles of Neural Coding. Boca Raton, FL: CRC Press, 201
3, 303–321.
As for the advice to focus on just one or two general messages, Carol, Richard’s wife, told me some time later that it was she who recommended this rule to him as she heard him rehearse his talks.
15In the first part of this fragment, James quotes from: James Mill. Analysis of the Phenomena of the Human Mind. Vol. 1. London: Baldwin & Cradock, 1829, 235.
16This, of course, applies to adults as well. I have seen this firsthand while teaching physics to high school and first-year university students. Few people struggle when asked at what constant speed a car must travel to cover 500 meters in two minutes. On the other hand, students find the exact same problem to be more challenging when formulated in a different way. For example: “I have only two minutes to pick up my sister from the supermarket, which is 500 meters away from home; if I keep the speed constant along the way, how fast should I drive to make it on time?” In fact, one of the first and most difficult things that students must learn is to comprehend what they are being asked and then set out a strategy to solve the problem. This, again, involves identifying and discarding irrelevant information to focus on what matters—the car has to cover 500 meters in two minutes, whether to go to a supermarket, to test-drive a new set of tires, etc.
Chapter 7
1See, for example: Alan Baddeley, Michael Eysenck, and Michael Anderson. Memory. New York: Psychology Press, 2009.
2George Sperling. “The information available in brief visual presentation.” Psychological Monographs 74 (11) (1960): 1–29.
3In the case of the visual system, sensory memory is also called iconic memory. Its aural counterpart, called echoic memory, is analogous, but unlike iconic memories, which last for a fraction of a second, echoic memories can last up to three or four seconds.
4Richard Atkinson and Richard Shiffrin. “Human memory: A proposed system and its control processes.” In K. W. Spence and J. T. Spence, eds. The Psychology of Learning and Motivation. Vol. 2. New York: Academic Press, 1968, 89–195.
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