Текст книги "Свобода воли"
Автор книги: Сэм Харрис
Жанры:
Психология
,сообщить о нарушении
Текущая страница: 5 (всего у книги 5 страниц)
Комментарии
1
Последние достижения в экспериментальной психологии и нейрокартографии позволили нам изучать границы между сознательными и бессознательными процессами в жизни с большей тщательностью. Теперь мы знаем по крайней мере две системы в мозгу – часто их называют “двойственным процессом” – управляющие человеческим сознанием, эмоциями, поведением. Кто-то эволюционно старше, бессознательнее, медленнее учится и медленнее отвечает. Феномен прайминга, который описывает подсознательно представленные стимулы, воздействующие на человеческие мысли и эмоции, позволяет по-новому взглянуть на эти стимулы и приоткрывает реальность сложных умственных процессов, скрывающихся под уровнем сознательности. Люди могут испытывать влияние разного рода, и эти бессознательные воздействия действительно меняют их цели и последующее действие.
(H. Aarts, R. Custers, & H. Marien, 2008. Preparing and motivating behavior outside of awareness. Science 319[5780]: 1639; R. Custers & H. Aarts, 2010. The unconscious will: How the pursuit of goals operates outside of conscious awareness. Science 329 [5987]: 47–50).
Экспериментальные техники “обратной маскировки” были центром большинства из этих работ: если кому-то показывают субъект кратким визуальным стимулом (около 30 миллисекунд), они могут сознательно осознать его, но они не смогут сделать то же, если за стимулом следует непохожий паттерн (“маска”). Эта техника позволяет доставлять слова и картинки в мозг сублиминально. Интересно, что порог для сознательного узнавания эмоциональных слов ниже, чем для нейтральных слов, из чего следует, что семантические процессы возникают до сознательности.
(R. Gaillard, A. Del Cul, L. Naccache, F. Vinckier, L. Cohen, & S. Dehaene, 2006. Nonconscious semantic processing of emotional words modulates conscious access. Proc. Natl. Acad. Sci. USA 103[19]: 7524–7529).
Последние нейрокартографические эксперименты предлагают дальнейшие свидетельства: замаскированные слова вовлекают области ассоциирующиеся с семантической обработкой (M. T. Diaz & G. McCarthy, 2007. Unconscious word processing engages a distributed network of brain regions. J. Cogn. Neurosci. 19[11]: 1768–1775; S. Dehaene, L. Naccache, L. Cohen, D. Le Bihan, J. F. Mangin, J. B. Poline, et al., 2001. Cerebral mechanisms of word masking and unconscious repetition priming. Nat. Neurosci. 4[7]: 752–758; S. Dehaene, L. Naccache, H. G. Le Clec, E. Koechlin, M. Mueller, G. Dehaene-Lambertz, et al., 1998. Imaging unconscious semantic priming. Nature 395[6702]: 597–600); subliminally promised rewards alter activity in the brain’s reward regions and influence subsequent behavior (M. Pessiglione, L. Schmidt, B. Draganski, R. Kalisch, H. Lau, R. J. Dolan, et al., 2007. How the brain translates money into force: A neuroimaging study of subliminal motivation. Science 316[5826]: 904–906); and masked fearful faces and emotional words drive activity in the amygdala, the hub of emotional processing in the limbic system (P. J. Whalen, S. L. Rauch, N. L. Etcoff, S. C. McInerney, M. B. Lee, & M. A. Jenike, 1998. Masked presentations of emotional facial expressions modulate amygdala activity without explicit knowledge. J. Neurosci. 18[1]: 411–418; L. Naccache, R. Gaillard, C. Adam, D. Hasboun, S. Clemenceau, M. Baulac, et al., 2005. A direct intracranial record of emotions evoked by subliminal words. Proc. Natl. Acad. Sci. USA 102[21]: 7713–7717).
The subliminal presentation of stimuli poses some conceptual problems, however. As Daniel Dennett points out, it can be difficult (or impossible) to distinguish what was experienced and then forgotten from what was never experienced in the first place—see his insightful discussion of Orwellian vs. Stalinesque processes in cognition (D. C. Dennett, 1991. Consciousness explained. Boston: Little, Brown and Co., pp. 116–125). This ambiguity is largely attributable to the fact that the contents of consciousness must be integrated over time—around 100 to 200 milliseconds (F. Crick & C. Koch, 2003. A framework for consciousness. Nat. Neurosci. 6[2]: 119–126). This period of integration allows the sensation of touching an object and the associated visual perception of doing so, which arrive at the cortex at different times, to be experienced as though they were simultaneous. Consciousness, therefore, is dependent upon what is generally known as “working memory.” Many neuroscientists have made this same point (J. M. Fuster, 2003. Cortex and mind: Unifying cognition. Oxford: Oxford University Press; P. Thagard & B. Aubie, 2008. Emotional consciousness: A neural model of how cognitive appraisal and somatic perception interact to produce qualitative experience. Conscious. Cogn. 17(3): 811–834; B. J. Baars & S. Franklin, 2003. How conscious experience and working memory interact. Trends Cogn. Sci. 7(4): 166–172). The principle is somewhat more loosely captured by Gerald Edelman’s notion of consciousness as “the remembered present” (G. M. Edelman, 1989. The remembered present: A biological theory of consciousness. New York: Basic Books).
2
B. Libet, C. A. Gleason, E. W. Wright, & D. K. Pearl, 1983. Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential): The unconscious initiation of a freely voluntary act, Brain 106 (Pt 3): 623–642; B. Libet, 1985. Unconscious cerebral initiative and the role of conscious will in voluntary action. Behav. Brain Sci. 8: 529–566. Another lab has since found that a person’s judgment of when he intended to move can be shifted in time by giving him delayed sensory feedback of his actual movements. This suggests that such judgments are retrospective estimates based on the apparent time of movement and not based on an actual awareness of the neural activity that causes the movement (W. P. Banks & E. A. Isham, 2009). We infer rather than perceive the moment we decided to act. (Psychological Science, 20: 17–21).
3
J. D. Haynes, 2011. Decoding and predicting intentions. Ann. NY Acad. Sci. 1224(1): 9–21.
4
I. Fried, R. Mukamel, & G. Kreiman, 2011. Internally generated preactivation of single neurons in human medial frontal cortex predicts volition. Neuron, 69: 548– 562; P. Haggard, 2011. Decision time for free will. Neuron, 69: 404–406.
5
The neuroscientists Joshua Greene and Jonathan Cohen make a similar point:
6
For a good survey of compatibilist thought, see http://plato.stanford.edu/entries/compatibilism/. See also G. Watson, ed., 2003. Free will (second edition). Oxford: Oxford University Press.
7
D. C. Dennett, 2003. Freedom evolves. New York: Penguin.
8
Tom Clark, personal communication.
9
Daniel Dennett, personal communication.
10
Galen Strawson (personal communication) has pointed out that even if one agrees with Dennett here, the ordinary notion of moral responsibility is still deeply problematic for the reasons already given.
11
In his book Consciousness Explained, Daniel Dennett describes an unpublished experiment in which the neurosurgeon W. Grey Walter directly connected the motor cortices of his patients to a slide projector. Asked to advance the slides at their leisure, the subjects were said to have felt that the projector was reading their minds. Unfortunately, there is some uncertainty as to whether the experiment was ever performed.
12
D. Wegner, 2002. The illusion of conscious will. Cam-bridge, MA: Bradford Books/MIT Press.
13
L. Silver, 2006. Challenging nature: The clash of science and spirituality at the new frontiers of life. New York: Ecco, p. 50.
14
For a recent discussion of the role of consciousness in human psychology, see R. F. Baumeister, E. J. Masicampo, & K. D. Vohs, 2011. Do conscious thoughts cause behavior? Annual Review of Psychology, 62: 331–361.
15
Again, as Galen Strawson points out (personal communication), even if we granted that you are the whole of your mind (conscious and unconscious), you still cannot ultimately be held responsible for its character.
16
Einstein (following Schopenhauer) once made the same point:
17
As Jerry Coyne points out (personal communication), this notion of counterfactual freedom is also scientifically untestable. What evidence could possibly be put forward to show that one could have acted differently in the past?
18
http://opinionator.blogs.nytimes.com/2011/11/13/is-neuroscience-the-death-of-free-will/.
19
K. D. Vohs & J. W. Schooler, 2008. The value of believing in free will: Encouraging a belief in determinism increases cheating. Psychological Science, 19(1): 49–54.
20
R. F. Baumeister, E. J. Masicampo, & C. N. DeWall, 2009. Prosocial benefits of feeling free: Disbelief in free will increases aggression and reduces helpfulness. Personality and Social Psychology Bulletin, 35: 260–268.
21
J. Diamond, 2008. Vengeance is ours. The New Yorker, April 21, 2001, NOTES
22
Steven Pinker, personal communication
