Authors: David Eagleman
Incognito (35 page)
Throughout the book you will often find the narrator’s term we instead of I. This is for three reasons. First, as with any book that synthesizes large bodies of knowledge, I collaborate with thousands of scientists and historians over the course of centuries. Second, the reading of a book should be an active collaboration between reader and writer. Third, our brains are composed of vast, complex, and shifting collections of subparts, most of which we have no access to; this book was written over the course of a few years by several different people, all of whom were named David Eagleman, but who were somewhat different with each passing hour.
David Eagleman
is a neuroscientist at Baylor College of Medicine, where he directs the Laboratory for Perception and Action as well as the Initiative on Neuroscience and Law. His scientific research has been published in journals from
Science
to
Nature
, and his neuroscience books include
Wednesday Is Indigo Blue: Discovering the Brain of Synesthesia
(with Richard Cytowic) and the forthcoming
Live-Wired
. He is also the author of the internationally best-selling book of fiction
Sum: Forty Tales from the Afterlives
.
SUM
is also available as an eBook: 978-0-307-37802-6
Visit David Eagleman’s website:
www.eagleman.com
Or follow him on:
twitter.com/@davideagleman
Works listed in full in the Bibliography are referred to only by short title here.
1
Music: “Tremendous Magic,”
Time
December 4, 1950.
2
Something I’ve always found inspiring: the year Galileo died—1642—Isaac Newton was born into the world and completed Galileo’s job by describing the equations underlying the planetary orbits around the sun.
3
Aquinas,
Summa theologiae
.
4
Specifically, Leibniz envisioned a machine that would use marbles (representing binary numbers) that would be guided by what we now recognize as cousins to punch cards. Although Charles Babbage and Ada Lovelace are generally credited with working out the concepts of software separation, the modern computer is essentially no different than what Leibniz envisaged: “This [binary] calculus could be implemented by a machine (without wheels) in the following manner, easily to be sure and without effort. A container shall be provided with holes in such a way that they can be opened and closed. They are to be open at those places that correspond to a 1 and remain closed at those that correspond to a 0. Through the opened gates small cubes or marbles are to fall into tracks, through the others nothing. It [the gate array] is to be shifted from column to column as required.” See Leibniz,
De
Progressione Dyadica
. Thanks to George Dyson for this discovery in the literature.
5
Leibniz,
New Essays on Human Understanding
, published 1765. By “insensible corpuscles,” Leibniz is referring to the belief shared by Newton, Boyle, Locke, and others that material objects are made of tiny insensible corpuscles, which give rise to the sense qualities of the objects.
6
Herbart,
Psychology as a Science
.
7
Michael Heidelberger,
Nature from Within
.
8
Johannes Müller,
Handbuch der Physiologie des Menschen, dritte verbesserte Auflage
, 2 vols (Coblenz: Hölscher, 1837–1840).
9
Cattell, “The time taken up,” 220–242.
10
Cattell, “The psychological laboratory,” 37–51.
Chapter 2. The Testimony of the Senses12
Freud and Breuer,
Studien über Hysterie.
1
Eagleman, “Visual illusions.”
2
Sherrington,
Man on His Nature
. See also Sheets-Johnstone, “Consciousness: a natural history.”
3
MacLeod and Fine, “Vision after early blindness.”
4
Eagleman, “Visual illusions.”
5
See eagleman.com/incognito for interactive demonstrations of how little we perceive of the world. For excellent reviews on change blindness, see Rensink, O’Regan, and Clark, “To see or not to see”; Simons, “Current approaches to change blindness”; and Blackmore, Brelstaff, Nelson, and Troscianko, “Is the richness of our visual world an illusion?”
6
Levin and Simons, “Failure to detect changes to attended objects.”
7
Simons and Levin, “Failure to detect changes to people.”
8
Macknik, King, Randi, et. al., “Attention and awareness in stage magic.”
9
The concept of a 2.5-D sketch was introduced by the late neuroscientist David Marr. He originally proposed this as an intermediate stage on the visual system’s journey to developing a full 3-D model, but it has since become clear that the full 3-D model never comes to fruition in real brains, and is not needed to get by in the world. See Marr,
Vision
.
10
O’Regan, “Solving the real mysteries of visual perception,” and Edelman,
Representation and Recognition in Vision.
Note that one group recognized the problem early on, in 1978, but it took many years to become more widely recognized: “The primary function of perception is to keep our internal framework in good registration with that vast external memory, the external environment itself,” noted Reitman, Nado, and Wilcox in “Machine perception,” 72.
11
Yarbus, “Eye movements.”
12
This phenomenon is known as binocular rivalry. For reviews, see Blake and Logothetis, “Visual competition” and Tong, Meng, and Blake, “Neural bases.”
13
The hole of missing photoreceptors occurs because the optic nerve passes through this location in the retina, leaving no room for the light-sensing cells. Chance, “Ophthalmology,” and Eagleman, “Visual illusions.”
14
Helmholtz,
Handbuch.
15
Ramachandran, “Perception of shape.”
16
Kersten, Knill, Mamassian, and Bülthoff, “Illusory motion.”
17
Mather, Verstraten, and Anstis,
The Motion Aftereffect
, and Eagleman, “Visual illusions.”
18
Dennett,
Consciousness Explained
.
19
Baker, Hess, and Zihl, “Residual motion”; Zihl, von Cramon, and Mai, “Selective disturbance”; and Zihl, von Cramon, Mai, and Schmid, “Disturbance of movement vision.”
20
McBeath, Shaffer, and Kaiser, “How baseball outfielders.”
21
It turns out that fighter pilots use this same algorithm during pursuit tasks, as do fish and hoverflies. Pilots: O’Hare, “Introduction”; fish: Lanchester and Mark, “Pursuit and prediction”; and hoverflies: Collett and Land, “Visual control.”
22
Kurson,
Crashing Through
.
23
It should be noted that some blind people can convert their felt world to two- or three-dimensional drawings. However, it is presumably the case that drawing the converging lines of a hallway is a cognitive exercise for them, different from the way that sighted people have the immediate sensory experience.
24
Noë,
Action in Perception
.
25
P. Bach-y-Rita, “Tactile sensory substitution studies.”
26
Bach-y-Rita, Collins, Saunders, White, and Scadden, “Vision substitution.”
27
For an overview and synthesis of these studies, see Eagleman,
Live-Wired
. Nowadays it is popular for the tactile display to come from an electrode grid placed directly on the tongue. See Bach-y-Rita, Kaczmarek, Tyler, and Garcia-Lara, “Form perception.”
28
Eagleman,
Live-Wired
.
29
C. Lenay, O. Gapenne, S. Hanneton, C. Marque, and C. Genouel, “Sensory substitution: Limits and perspectives,” in
Touching for Knowing, Cognitive Psychology of Haptic Manual Perception
(Amsterdam: John Benjamins, 2003), 275–92, and Eagleman,
Live-Wired
.
30
The BrainPort is made by Wicab, Inc, a company founded by plasticity pioneer Paul Bach-y-Rita.
31
Bach-y-Rita, Collins, Saunders, White, and Scadden, “Vision substitution”; Bach-y-Rita, “Tactile sensory substitution studies”; Bach-y-Rita, Kaczmarek, Tyler, and Garcia-Lara, “Form perception”; M. Ptito, S. Moesgaard, A. Gjedde, and R. Kupers, “Cross-modal plasticity revealed by electrotactile stimulation of the tongue in the congenitally blind,”
Brain
128 (2005), 606–14; and Bach-y-Rita, “Emerging concepts of brain function,”
Journal of Integrative Neuroscience
4 (2005), 183–205.
32
Yancey Hall. “Soldiers may get ‘sight’ on tips of their tongues,”
National Geographic News
, May 1, 2006.
33
B. Levy, “The blind climber who ‘sees’ with his tongue,”
Discover
, June 23, 2008.
34
Hawkins,
On Intelligence
, and Eagleman,
Live-Wired
.
35
Gerald H. Jacobs, Gary A. Williams, Hugh Cahill, and Jeremy Nathans, “Emergence of novel color vision in mice engineered to express a human cone photopigment,”
Science
23 (2007): vol. 315. no. 5819, 1723–25. For a detracting opinion about the interpretation of results, see Walter Makous, “Comment on ‘Emergence of novel color vision in mice engineered to express a human cone photopigment,”
Science
(2007): vol. 318. no. 5848, 196, in which he argues that it is impossible to conclude much of anything about the internal experience of the mice, a precondition for claiming that they experienced color vision as opposed to different levels of light and dark. Whatever the internal experience of the mice, it is clear that their brains have integrated the information from the new photopigments and can now discriminate features that they could not before. Importantly, this technique is now possible in rhesus monkeys, a method that should open the door to asking the correct, detailed perceptual questions.
36
Jameson, “Tetrachromatic color vision.”
37
Llinas,
I of the Vortex
.
38
Brown, “The intrinsic factors.” Although Brown was well known in the 1920s for his pioneering neurophysiology experiments, he became even better known in the 1930s for his world-famous mountaineering expeditions and discoveries of new routes to the summit of Mont Blanc.
39
Bell, “Levels and loops.”
40
McGurk and MacDonald, “Hearing lips,” and Schwartz, Robert-Ribes, and Escudier, “Ten years after Summerfield.”
41
Shams, Kamitani, and Shimojo, “Illusions.”
42
Gebhard and Mowbray, “On discriminating”; Shipley, “Auditory flutter-driving”; and Welch, Duttonhurt, and Warren, “Contributions.”
43
Tresilian, “Visually timed action”; Lacquaniti, Carrozzo, and Borghese, “Planning and control of limb impedance”; Zago, et. al., “Internal models”; McIntyre, Zago, Berthoz, and Lacquaniti, “Does the brain model Newton’s laws?”; Mehta and Schaal, “Forward models”; Kawato, “Internal models”; Wolpert, Ghahramani, and Jordan, “An internal model”; and Eagleman, “Time perception is distorted during visual slow motion,” Society for Neuroscience, abstract, 2004.
44
MacKay, “Towards an information-flow model”; Kenneth Craik,
The Nature of Explanation
(Cambridge, UK: Cambridge University Press, 1943); Grush, “The emulation theory”. Also see Kawato, Furukawa, and Suzuki, “A hierarchical neural-network model”; Jordan and Jacobs, “Heirarchical mixtures of experts”; Miall and Wolpert, “Forward models”; and Wolpert and Flanagan, “Motor prediction.”