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.”
45 Grossberg, “How does a brain … ?”; Mumford, “On the computational architecture”; Ullman, “Sequence seeking”; and Rao, “An optimal estimation approach.”
46 MacKay, “The epistemological problem.”
47 See Blakemore, Wolpert, and Frith, “Why can’t you tickle yourself?” for more about tickling. More generally, violations of sensory expectations can inform a brain about responsibility—that is, did I cause the action or did someone else? Schizophrenic hallucinations may arise from a failure of matching expectations about one’s own motor acts to their resulting sensory signals. Failure to distinguish one’s own actions from those of independent agents means that the patient attributes his internal voices to someone else. For more on this idea, see Frith and Dolan, “Brain mechanisms.”
48 Symonds and MacKenzie, “Bilateral loss of vision.”
49 Eagleman and Sejnowski, “Motion integration,” and Eagleman, “Human time perception.”
50 Eagleman and Pariyadath, “Is subjective duration … ?”
Chapter 3. Mind: The Gap
1 Macuga, et al., “Changing lanes.”
2 Schacter, “Implicit memory.”
3 Ebbinghaus, Memory: A Contribution to Experimental Psychology.
4 Horsey, The Art of Chicken Sexing; Biederman and Shiffrar, “Sexing day-old chicks”; Brandom, “Insights and blindspots of reliabilism”; and Harnad, “Experimental analysis.”
5 Allan, “Learning perceptual skills.”
6 Cohen, Eichenbaum, Deacedo, and Corkin, “Different memory systems,” and Brooks and Baddeley, “What can amnesic patients learn?”
7 As another example of tying things together at an unconscious level, subjects were given a carbonated drink, and then their chairs were rocked back and forth to induce motion sickness. As a result, the subjects established an aversion to the carbonated drink, even though they well knew (consciously) that the drink had nothing to do with the nauseating motion. See Arwas, Rolnick, and Lubow, “Conditioned taste aversion.”
8 Greenwald, McGhee, and Schwartz, “Measuring individual differences.”
9 The implicit association test can be taken online: https://implicit.harvard.edu/implicit/demo/selectatest.html.
10 Wojnowicz, Ferguson, Dale, and Spivey, “The self-organization of explicit attitudes.” See also Freeman, Ambady, Rule, and Johnson, “Will a category cue attract you?”
11 Jones, Pelham, Carvallo, and Mirenberg, “How do I love thee?”
12 Ibid.
13 Pelham, Mirenberg, and Jones, “Why Susie sells,” and Pelham, Carvallo, and Jones, “Implicit egotism.”
14 Abel, “Influence of names.”
15 Jacoby and Witherspoon, “Remembering without awareness.”
16 Tulving, Schacter, and Stark, “Priming effects.” These effects hold even if I distract you so much that we’re certain you cannot explicitly remember what the words were; you’re still just as good at the word completion. See Graf and Schacter, “Selective effects.”
17 The idea of priming has a rich history in literature and entertainment. In The Subliminal Man, by J. G. Ballard (1963), a character named Hathaway is the only one who suspects that the dozens of gigantic blank signs towering over the roads are really subliminal advertising machines, encouraging people to take on more jobs and buy more products. A more droll incarnation of Subliminal Man can be found in comedian Kevin Nealon’s Saturday Night Live character, who says, during a talk show interview, “I’ve always liked watching this show (nauseating). It’s fun to be a guest on this show (torture). It’s kind of like a second home to me (Titanic).”
18 Graf and Schacter, “Implicit and explicit memory.”
19 See Tom, Nelson, Srzentic, and King, “Mere exposure.” For a more basic approach to demonstrating that the brain can absorb what it has seen even without attention to it, see Gutnisky, Hansen, Iliescu, and Dragoi, “Attention alters visual plasticity.”
20 Ironically, no one is quite sure who said this first. The
quotation has been variously attributed to Mae West, P. T. Barnum, George M. Cohan, Will Rogers, and W. C. Fields, among others.
21 Hasher, Goldstein, and Toppino, “Frequency and the conference of referential validity.”
22 Begg, Anas, and Farinacci, “Dissociation of processes in belief.”
23 Cleeremans, Mechanisms of Implicit Learning.
24 Bechara, Damasio, Tranel, and Damasio, “Deciding advantageously.”
25 Damasio, “The somatic marker hypothesis”; Damasio, Descartes’ Error; and Damasio, The Feeling of What Happens.
26 Eagleman, Live-Wired.
27 Montague, Your Brain Is (Almost) Perfect.
28 If you watch athletes closely, you will notice they often employ physical rituals to get themselves into the zone—for example, dribbling the ball exactly three times, cranking their neck to the left, and then shooting. By providing predictability, these rituals ease them into a less conscious state. To the same end, repetitive and predictable rituals are routinely used in religious services—for example, rote prayers, rosary counting, and chants all help to relax the buzzing of the conscious mind.
Chapter 4. The Kinds of Thoughts That Are Thinkable
1 Blaise Pascal, Pensées, 1670.
2 All of these signals (radio, microwave, X-ray, gamma ray, cell phone transmissions, television broadcasts, and so on) are exactly the same thing as the stuff coming out of the front of your flashlight—just of a different wavelength. Some readers already knew this; for those who didn’t, the sheer amazingness of this simple scientific fact urges its inclusion.
3 Jakob von Uexküll introduced the idea of the umwelt in 1909 and explored it through the 1940s. It was then lost for decades until rediscovery and revivification by the semiotician Thomas A. Sebeok in 1979; Jakob von Uexküll, “A stroll through the worlds of animals and men.” See also Giorgio Agamben, Chapter 10, “Umwelt”, in his book The Open: Man and Animal, trans. Kevin Attell (Palo Alto: Stanford University Press, 2004); originally published in Italian in 2002 as L’aperto: l’uomo e l’animale.
4 K. A. Jameson, S. Highnote, and L. Wasserman, “Richer color experience in observers with multiple photopigment opsin genes,” Psychonomic Bulletin & Review, 8, no.2 (2001): 244–61; and Jameson, “Tetrachromatic color vision.”
5 For more about synesthesia, see Cytowic and Eagleman, Wednesday Is Indigo Blue.
6 Think you might have synesthesia? Take the free online tests at www.synesthete.org. See Eagleman, et al., “A standardized test battery for the study of synesthesia.”
7 Our laboratory has turned to the details of synesthesia—from behavior to neuroimaging to genetics—to use it as an inroad into understanding how slight differences in the brain can lead to large differences in the perception of reality. See www.synesthete.org.
8 In other words, the forms have a location in mental space that can be pointed to. If you’re not a spatial sequence synesthete, imagine your car parked in the space in front of you. Although you do not physically see it there like a hallucination, you will have no trouble pointing to the front wheel, the driver’s side window, the rear bumper, and so on. The car has three-dimensional coordinates in your mental space. So it goes with automatically triggered number forms. Unlike hallucinations, they do not overlie the outside visual world; they instead live in a mental space. In fact, even blind subjects can experience number form synesthesia; see Wheeler and Cutsforth, “The number forms of a blind subject.” For a larger discussion of spatial sequence synesthesia, see Eagleman, “The objectification of overlearned sequences,” and Cytowic and Eagleman, Wednesday Is Indigo Blue.
9 Eagleman, “The objectification of overlearned sequences.”
10 An interesting speculation is that all brains are synesthetic––but the majority of us remain unconscious of the sensory fusions going on in our brains under the surface of awareness. In fact, everyone seems to possess implicit number lines for sequences. When asked, we might agree that the number line for integers increases as one goes from left to right. Spatial sequence synesthetes differ in that they experience sequences explicitly in three dimensions as automatic, consistent, and concrete configurations. See Eagleman, “The objectification of overlearned sequences”, and Cytowic and Eagleman, Wednesday Is Indigo Blue.
11 Nagel, The View from Nowhere.
12 See Cosmides and Tooby, Cognitive Adaptations, for an overview, and Steven Pinker’s The Blank Slate for an excellent in-depth read.
13 Johnson and Morton, “CONSPEC and CONLERN.”
14 Meltzoff, “Understanding the intentions of others.”
15 Pinker, The Blank Slate.
16 Wason and Shapiro, “Reasoning,” and Wason, “Natural and contrived experience”
17 Cosmides and Tooby, Cognitive Adaptions.
18 Barkow, Cosmides, and Tooby, The Adapted Mind
19 Cosmides and Tooby, “Evolutionary psychology: A primer,” 1997; http://www.psych.ucsb.edu/research/cep/primer.html
20 James, The Principles of Psychology.
21 Tooby and Cosmides, Evolutionary Psychology: Foundational Papers (Cambridge, MA: MIT Press, 2000).
22 Singh, “Adaptive significance” and “Is thin really beautiful,” and Yu and Shepard, “Is beauty in the eye?”
23 More generally, women with waists thinner than this range are seen as more aggressive and ambitious, while those with thicker waists are viewed as kind and faithful.
24 Ramachandran, “Why do gentlemen …?”
25 Penton-Voak, et al., “Female preference for male faces changes cyclically.”
26 Vaughn and Eagleman, “Faces briefly glimpsed.”
27 Friedman, McCarthy, Förster, and Denzler, “Automatic effects.” It may even be the case that other concepts related to alcohol (such as sociability) may also be activated by priming to alcohol-related words—such that merely seeing (not drinking) a glass of wine could lead to easier conversation and more eye contact. A more speculative and challenging possibility is that seeing advertisements for alcohol along highway billboards could lead to diminished driving performance.
28 Concealed ovulation (as well as internal fertilization, as opposed to the laying of external eggs) may have come about as a mechanism that encourages males to remain attentive to their female mates equally at all times, thereby diminishing the chances of desertion.
29 Roberts, Havlicek, and Flegr, “Female facial attractiveness increases.”
30 Symmetry of ears, breasts, and fingers during ovulation: Manning, Scutt, Whitehouse, Leinster, and Walton, “Asymmetry,” Scutt and Manning, “Symmetry”; for lighter skin tone, see Van den Berghe and Frost, “Skin color preference.”
31 G. F. Miller, J. M. Tybur, and B. D. Jordan, “Ovulatory cycle effects on tip earnings by lap-dancers: Economic evidence for human estrus?” Evolution and Human Behavior, 28 (2007): 375–81.
32 Liberles and Buck, “A second class.” Because humans also carry the genes for this family of receptors, it’s the most promising road to sniff down when looking for a role for pheromones in humans.
33 Pearson, “Mouse data.”
34 C. Wedekind, T. Seebeck, F. Bettens, and A. J. Paepke, “MHC-dependent mate preferences in humans.” Proceeding of the Royal Society of London Series B: Biological Sciences 260, no. 1359 (1995): 245–49.
35 Varendi and Porter, “Breast odour.”
36 Stern and McClintock, “Regulation of ovulation by human pheromones.” While it is widely believed that women living together will synchronize their menstrual cycles, it appears that this is not true. Careful studies of the original reports (and subsequent large-scale studies) show that statistical fluctuations can give the perception of synchrony but are nothing but chance occurrence. See Zhengwei and Schank, “Women do not synchronize.”
37 Moles, Kieffer, and D’Amato, “Deficit in attachment behavior.”
38 Lim, et al., “Enhanced partner preference.”
39 H. Walum, L. Westberg, S. Henningsson, J. M. Neiderhiser, D. Reiss, W. Igl,
J. M. Ganiban, et al.,“Genetic variation in the vasopressin receptor 1a gene (AVPR1A) associates with pair-bonding behavior in humans.” PNAS 105, no.37 (2008): 14153–56.
40 Winston, Human Instinct.
41 Fisher, Anatomy of Love.
Chapter 5. The Brain Is a Team of Rivals
1 See Marvin Minsky’s 1986 book Society of Mind.
2 Diamond, Guns, Germs, and Steel.
3 For a concrete illustration of the advantages and shortcomings of a “society” architecture, consider the concept of subsumption architecture, pioneered by the roboticist Rodney Brooks (Brooks, “A robust layered”). The basic unit of organization in the subsumption architecture is a module. Each module specializes in some independent, low-level task, such as controlling a sensor or actuator. The modules operate independently, each doing its own task. Each module has an input and an output signal. When the input of a module exceeds a predetermined threshold, the output of the module is activated. Inputs come from sensors or other modules. Each module also accepts a suppression signal and an inhibition signal. A suppression signal overrides the normal input signal. An inhibition signal causes output to be completely inhibited. These signals allow behaviors to override each other so that the system can produce coherent behavior. To produce coherent behavior, the modules are organized into layers. Each layer might implement a behavior, such as wander or follow a moving object. These layers are hierarchical: higher layers can inhibit the behavior of lower ones by inhibition or suppression. This gives each level its own rank of control. This architecture tightly couples perception and action, producing a highly reactive machine. But the downside is that all patterns of behavior in these systems are prewired. Subsumption agents are fast, but they depend entirely on the world to tell them what to do; they are purely reflexive. In part, subsumption agents have far-from-intelligent behavior because they lack an internal model of the world from which to make conclusions. Rodney Brooks claims this is an advantage: by lacking representation, the architecture avoids the time necessary to read, write, utilize, and maintain the world models. But somehow, human brains do put in the time, and have clever ways of doing it. I argue that human brains will be simulated only by moving beyond the assembly line of sequestered experts into the idea of a conflict-based democracy of mind, where multiple parties pitch in their votes on the same topics.