Abstract
The paper proposes a minimal definition of dreaming in terms of immersive spatiotemporal hallucination (ISTH) occurring in sleep or during sleep–wake transitions and under the assumption of reportability. I take these conditions to be both necessary and sufficient for dreaming to arise. While empirical research results may, in the future, allow for an extension of the concept of dreaming beyond sleep and possibly even independently of reportability, ISTH is part of any possible extension of this definition and thus is a constitutive condition of dreaming. I also argue that the proposed ISTH model of dreaming, in conjunction with considerations on the epistemic relationship between dreaming and dream reports, raises important questions about the extent to which dreams typically involve a detailed body representation—an assumption that plays an important role in philosophical work on dreaming. As a commonly accepted definition of dreaming is lacking in current dream research, the ISTH model, which integrates conceptual analysis and epistemological considerations with results from empirical research, is an important contribution to this field. By linking dreaming to felt presence, full-body illusions, and autoscopic phenomena such as out-of-body experiences in wakefulness and in the hypnagogic state, the ISTH model of dreaming also helps integrate dream research, both theoretically and experimentally, with the study of other altered states of consciousness involving hallucinations. It makes straightforward and investigable predictions by claiming that all of these experiences have amodal spatiotemporal hallucinations as their common denominator. Finally, it is theoretically relevant for the philosophical discussion on minimal phenomenal selfhood.
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Notes
On the view espoused here, dreaming is distinguished from imagination by the sense of immersion in a hallucinatory space. This differs from the type of fictional immersion that dreams, according to the imagination model, share with daydreams or waking fantasies (McGinn 2004, 2005). Dreams also only rarely, with the exception of lucid control dreams, exhibit the type of agentive control required on the imagination model. Most attempts to conceptualize dreaming as imagination (rather than hallucination) rely on a sharp distinction between perception, hallucination, and imagination. However, empirical evidence better supports the view that perception, hallucination, and waking imagination are deeply similar, both phenomenologically and in terms of the underlying neurocognitive mechanisms. Visual imagery, in particular, behaves like visual perception in terms of the time required to perform similarity judgments or mental rotation tasks, the overflow of the visual field, etc. (for an overview and further references, see Kosslyn 1994; Kind 2006; Grush 2004; Currie and Ravenscroft 2002:71ff). Perky (1910) showed that healthy subjects are prone to confuse perception and mental imagery under certain conditions. This may be especially pronounced in certain patient groups (Currie and Ravenscroft 2002:72ff). There is also compelling evidence both from neuroimaging and lesion studies for an overlap in the neural substrates involved in visual imagery and visual perception (Grush 2004: 387). With the sharp distinction between imagery and perception eroded, the argument for distinguishing dreaming from hallucination loses much of its force. The ISTH model can allow for a gradual distinction between imagination and hallucination, for instance regarding the intensity and color saturation of visual dream imagery, while maintaining only that a particular type of immersive spatiotemporal hallucination is constitutive of dreaming.
Early dream researchers tended, overly optimistically, to equate dreaming with REM sleep and viewed non-rapid eye movement (NREM) sleep as a state of unconsciousness, giving rise, at best, to thought-like mental activity. Today, most researchers accept that there is a double dissociation between dreaming and REM sleep: REM sleep can occur without dreaming, and, more importantly, even vivid dreams can occur during NREM sleep and sleep onset. For a review, see Nielsen (2000a, b). As Noreika et al. (2009) recently pointed out, these findings highlight the need for a correlate of dreaming independently of sleep stages. However, as long as it is unclear which type of experience—or more accurately, which type of retrospective experience report—should be classified as dreaming, the attempt to investigate its neural correlates is futile.
At least REM dreams arise in a state of near-complete functional disembodiment: the transmission of external stimuli from the primary sensory neurons is actively inhibited, preventing peripheral information from gaining access to the central nervous system. At the same time, the postsynaptic inhibition of the motor neurons in the brain stem and spinal cord prevents the external enactment of internally experienced dream behavior. See Hobson et al. 2000 for details. Of course, there are exceptions: loud stimuli, such as the sound of an alarm clock, can awaken the subject or become integrated in the dream. Also, patients with REM sleep behavior disorder (RBD), in whom the inhibition of motor neurons fails, enact their dreams. For details, see Mahowald and Schenck 1999; Schenck and Mahowald 1996; Schenck 2005. Sleep behavior during NREM sleep, such as sleepwalking, may also be associated with dreaming; see Revonsuo 2006.
A study reported by Bertolo et al. 2003 suggested (contrary to common belief) that congenitally blind subjects experience visual dreams. While this is highly controversial (see Kerr and Domhoff 2004; Lopes da Silva 2003), adventitiously blind subjects, who sometimes continue to experience visual dreams for years after losing their eyesight, also occasionally report nonvisual dreams.
Of course, reports from such a selfless state would involve a performative contradiction; see Metzinger 2003: 539. In lucid dreams in which the dreamer realizes that she is dreaming but experiences herself as disembodied or absent, there is still a cognitive self. In a very rudimentary sense that has to do with self-location, there is even still a bodily self. At least, these rudimentary forms of (bodily) self-experience are sufficient to give rise to retrospective reports of having been present, albeit in a disembodied manner. Descriptions of selfless and disembodied dreams may simply be different ways of retrospectively describing the same type of dream.
Similarly, Schwitzgebel 2002b has suggested that we may dream neither in color nor in black and white, but that dreams may be indeterminate with respect to color.
According to Metzinger 2003: 117 ff, phenomenal experience is characterized by global availability to attention, cognition and behavior.
Strictly speaking, epistemic underdetermination is a property of theories, not reports. The same is true for epistemic transparency and opacity. Thus, dream reports are epistemically underdetermined (transparent or opaque) given certain background assumptions about how they relate to the phenomenal character of the experience they are taken to refer to. They can also be regarded as a form of folk-psychological theory about what was experienced during sleep. Importantly, epistemic transparency, opacity and underdetermination differ not so much as to whether such an experience occurred, but as to whether dream reports justify such assumptions.
This assumption underlies most empirical and theoretical work on dreaming. However, this point is rarely made explicit.
There might be ways to decide the question. One could easily imagine, though less easily conduct, an extensive study involving scores of dreamers spending several nights in a scanner and reporting their dreams several times a night. By comparing references to bodily and movement sensations in their dream reports to images of regional activation patterns in the areas that correlate with these types of experiences during wakefulness, one might then decide the question. Due to the practical difficulties and the high cost of such studies, however, it would be hard to accumulate a sufficiently large database. Also, even persuasive results would still leave room for skepticism.
In the terminology introduced by Blanke and Metzinger’s 2008:7, this weak 1PP is a purely geometrical feature of an egocentric model of reality.
Though problematic, I use the term veridical perception as a contrast to hallucinatory or illusory cases, i.e. for those cases of perceptual experience in which a mind-independent object is actually present, its properties are not misperceived and there is a close degree of stimulus correlation. In doing so, I do not, however, commit to a version of direct or naïve realism about perception.
Note that while ISTH is distinguished from the feeling of self-location in perceptual space (in terms of a veridical perception of one’s actual environment), it may not always be possible to make the distinction. I.e., if you have a particularly realistic dream of waking up in your bedroom and then going back to sleep, you may never be sure, even retrospectively, whether you dreamt the episode or really woke up. So while ISTH is not the same as spatial location in perceptual space (precisely because it has a hallucinatory quality), the two can be epistemically indistinguishable not just while they are occurring, but even retrospectively.
Much as one is located relative to a movie screen without having the sensation of being localized or present in the scene one is observing. Another way of saying this is that you are located, both in a spatial and a temporal sense, relative to the screen without being localized relative to the objects, persons and events depicted in the movie, and the same description may apply to certain non-immersive visual hallucinations.
The argument of Kiverstein (2009) that minimal selfhood is a consequence of the temporal structure of consciousness also supports of this view.
One could argue that spatial imagery is in fact a type of modal imagery corresponding to some sort of “spatial sense”, much as is the case for proprioception. Whether the corresponding type of imagery is considered as modal or amodal, however, is a separate question that is beyond the scope of this paper. The important point for the ISTH model of dreaming is that immersive, purely spatiotemporal hallucinatory imagery rather than, for instance, visual or auditory imagery is both necessary and sufficient for dreaming.
In his extensive review of the neurological literature on losses of dreaming, Solms 1997 presents compelling evidence that a partial or complete loss of dreaming cannot be reduced to memory deficits. A rare study of so-called nondreamers, who never recalled dreaming spontaneously and were unable to report dreams following repeated REM sleep awakenings, also suggested that the inability to report dreams is independent of mnemonic deficiencies. See Pagel 2003.
In experimentally induced FBIs in virtual reality setups, for instance, subjects stand still throughout the illusion. See Lenggenhager 2009.
This is not to say that these cases lack an immersive quality altogether: of course, there is a sense of immersion in the perceptual environment. What they lack is the experience of immersion relative to a hallucinatory environment.
References
Aleman, A., & Larøi, F. (2008). Hallucinations. The science of idiosyncratic perception. Washington D.C.: American Psychological Association.
Arzy, S., Seeck, M., Ortigue, S., Spinelli, L., & Blanke, O. (2006). Induction of an illusory shadow person. Nature, 443, 287.
Bertolo, H., Paiva, T., Pessoa, L., Mestre, T., Marques, R., & Santos, R. (2003). Visual dream content, graphical representation and EEG alpha activity in congenitally blind subjects. Cognitive Brain Research, 15, 277–284.
Blackmore, S. (1988). A theory of lucid dreams and OBEs. In J. Gackenbach & S. LaBerge (Eds.), Conscious mind, sleeping brain. Perspectives on lucid dreaming. New York: Plenum.
Blanke, O., & Arzy, S. (2005). The out-of-body experience: disturbed self-processing at the temporo-parietal junction. The Neuroscientist, 11(1), 16–24.
Blanke, O., & Metzinger, T. (2008). Full-body illusions and minimal phenomenal selfhood. Trends in Cognitive Sciences, 13(1), 7–13.
Blanke, O., & Mohr, C. (2005). Out-of-body experience, heautoscopy, and autoscopic hallucination of neurological origin Implications for neurocognitive mechanisms of corporeal awareness and self-consciousness. Brain Research Reviews, 1;50(1), 184–199.
Blanke, O., Mohr, C., Michel, C. M., Pascual-Leone, A., Brugger, P., Seeck, M., et al. (2005). Linking out-of-body experience and self processing to mental own-body imagery at the temporoparietal junction. The Journal of Neuroscience, 25(3), 550–557.
de Boismont, A. B. (1860). On hallucinations: A history and explanation of apparitions, visions, dreams, ecstasy, magnetism, and somnambulism. Columbus: Riley.
Botvinick, M., & Cohen, J. (1998). Rubber hands ‘feel’ touch that eyes see. Nature, 391(6669), 756.
Brooks, J. E., & Vogelsong, J. A. (1999). The conscious exploration of dreaming. Discovering how we create and control our dreams. Bloomington: First Books Library.
Brugger, P. (2006). From phantom limb to phantom body: Varieties of extracorporeal awareness. In G. Knoblich, I. M. Thornton, M. Grosjean, & M. Shiffrar (Eds.), Human body perception from the inside out. Oxford: Oxford University Press.
Charcot, J. M. (1883). Un cas de suppression brusque et isolée de la vision mentale des signes et des objets, (formes et couleurs). Progrès Médical, 11, 568–571.
Cheyne, J. A. (2003). Sleep paralysis and the structure of waking-nightmare hallucinations. Dreaming, 13, 163–179.
Cheyne, J. A. (2005). Sleep paralysis episode frequency and number, types, and structure of associated hallucinations. Journal of Sleep Research, 14, 319–324.
Cheyne, J. A., & Girard, T. A. (2007). The nature and varieties of felt presence experiences: A reply to Nielsen. Consciousness and Cognition, 16, 984–991.
Cheyne, J. A., & Girard, T. A. (2009). The body unbound: Vestibular-motor hallucinations and out-of-body experiences. Cortex, 45(2), 201–215.
Cheyne, J. A., Rueffer, S. D., & Newby-Clark, I. R. (1999). Hypnagogic and hypnopompic hallucinations during sleep paralysis: neurological and cultural construction of the night-mare. Consciousness and Cognition, 8, 319–337.
Cigogna, P., Natale, V., Occhionero, M., & Bosinelli, M. (2000). Slow wave and REM sleep mentation. Sleep Research Online, 3, 67–72.
Crane, T. (2005). The problem of perception. Standford encyclopedia of philosophy. URL = http://plato.stanford.edu/entries/perception-problem.
Currie, G., & Ravenscroft, I. (2002). Recreative minds: Imagination in philosophy and psychology. Oxford: Clarendon.
Dang-Vu, T. T., Schabus, M., Desseilles, M., Schwartz, S., & Maquet, P. (2007). Neuroimaging of REM sleep and dreaming. In D. Barrett & P. McNamara (Eds.), The new science of dreaming Vol 1: Biological aspects. Santa Barbara: Greenwood.
Dennett, D. C. (1976). Are dreams experiences? Philosophical Review, 73, 151–171.
Descartes, R. (1911/1642). In E. S. Haldane & G. R. T. Ross (Eds.), Meditations on a first philosophy. Cambridge: Cambridge University Press.
Ehrsson, H. H. (2007). The experimental induction of out-of-body experiences. Science, 317(5841), 1048.
Esposito, M. J., Nielsen, T. A., & Paquette, T. (2004). Reduced alpha power associated with the recall of mentation from stage 2 and stage REM sleep. Psychophysiology, 41, 288–297.
Farah, M. J., Hammond, K. M., Levine, D. N., & Calvanio, R. (1988). Visual and spatial mental imagery: Dissociable systems of representation. Cognitive Psychology, 20, 439–462.
Gallagher, S. (2005). How the body shapes the mind. Oxford: Oxford University Press.
Germain, A., & Nielsen, T. A. (2001). EEG power associated with early sleep onset images differing in sensory content. Sleep Research Online, 4, 83–90.
Germain, A., & Nielsen, T. A. (2003). Sleep pathophysiology in posttraumatic stress disorder and idiopathic nightmare sufferers. Biological Psychiatry, 54, 1092–1098.
Green, C., & McCreery, C. (1994). Lucid dreaming. The paradox of consciousness during sleep. London: Routledge.
Grush, R. (2004). The emulation theory of representation: motor control, imagery, and perception. The Behavioral and Brain Sciences, 27, 377–442.
Hishikawa, Y., & Shimizu, T. (1995). Physiology of REM sleep, cataplexy and sleep paralysis. Advances in Neurology, 67, 245–271.
Hobson, J. A. (1988). The dreaming brain. New York: Basic Books.
Hobson, J. A., Pace-Schott, E. F., & Stickgold, R. (2000). Dreaming and the brain: Toward a cognitive neuroscience of conscious states. The Behavioral and Brain Sciences, 23(6), 793–842. 904-1018; 1083-1121.
Hunt, H. T. (1989). The multiplicity of dreams. Memory, imagination, and consciousness. New Haven: Yale University Press.
Ichikawa, J. (2009). Dreaming and imagination. Mind & Language, 24(1), 103–121.
Irwin, H. J. (1988). Out-of-the-body experiences and dream lucidity. Empirical perspectives. In J. Gackenbach & S. LaBerge (Eds.), Conscious mind, sleeping brain. Perspectives on lucid dreaming. New York: Plenum.
James, W. (2003[1902]). The varieties of religious experience. New York: Signet.
Kahn, D. (2007). Metacognition, recognition, and reflection while dreaming. In D. Barrett & P. McNamara (Eds.), The new science of dreaming Vol 1: Biological aspects. Santa Barbara: Greenwood.
Kerr, N. H. (1993). Mental imagery, dreams, and perception. In C. Cavallero & D. Foulkes (Eds.), Dreaming as cognition. New York: Harvester Wheatsheaf.
Kerr, N. H., & Domhoff, G. W. (2004). Do the blind literally “see” in their dreams? A critique of a recent claim that they do. Dreaming, 14(4), 230–233.
Kind, A. (2006). Imagery and imagination. The Internet Encyclopedia of Philsosophy. < http://209.85.129.132/search?q=cache:ntwzSHIM1esJ:www.iep.utm.edu/i/imagery.htm+imagination+perception+philosophy&cd=3&hl=de&ct=clnk&gl=de&client=firefox-a> Accessed 14 June 2009.
Kiverstein, J. D. (2009). Minimal sense of self, temporality and the brain. Psyche, 15(1), 59–74.
Kosslyn, S. (1994). Image and brain. Cambridge: MIT.
Kramer, M. (2007). The dream experience. A systematic exploration. New York: Routledge.
LaBerge, S., & DeGracia, D. J. (2000). Varieties of lucid dreaming. In R. G. Kunzendorf & B. Wallace (Eds.), Individual differences in conscious experience. Amsterdam: John Benjamins.
Lenggenhager, B. (2009). Multisensory mechanisms underlying bodily self-consciousness. Unpublished doctoral dissertation presented to Faculté des Sciences de la Vie, EPFL, Lausanne.
Lenggenhager, B., Tadi, T., Metzinger, T., & Blanke, O. (2007). Video ergo sum: Manipulating bodily self-consciousness. Science, 317(5841), 1096–1099.
Locke. (1997[1689]). An essay concerning human understanding. London: Penguin.
Lopes da Silva, F. H. (2003). Visual dreams in the congenitally blind? Trends in Cognitive Sciences, 7(8), 328–330.
Mahowald, M. W., & Schenck, C. H. (1999). Dissociated states of wakefulness and sleep. In R. Lydic & H. A. Baghdoyan (Eds.), Handbook of behavioral state control: Molecular and cellular mechanisms. Boca Raton: CRC.
Malcolm, N. (1956). Dreaming and skepticism. The Philosophical Review, 65, 14–37.
Malcolm, N. (1959). Dreaming. New York: Humanities.
Mavromatis, A. (1987). Hypnagogia. The unique state of consciousness between wakefulness and sleep. London: Routledge.
McGinn, C. (2004). Mindsight. Image, dream, meaning. Cambridge: Harvard University Press.
McGinn, C. (2005). The power of movies: How screen and mind interact (2005). Pantheon: Vintage.
Merritt, J. M., Stickgold, R., Pace-Schott, E., Williams, J., & Hobson, J. A. (1994). Emotion profiles in the dreams of men and women. Consciousness and Cognition, 3, 46–60.
Metzinger, T. (2003). Being no one. The self-model theory of subjectivity. Cambridge: MIT.
Metzinger, T. (2009). The ego tunnel. The science of the mind and the myth of the self. New York: Basic Books.
Nanay, B. (2009). Four theories of amodal perception. In D. S. McNamara & J. G. Trafton (Eds.), Proceedings of the 29th Annual Conference of the Cognitive Science Society (CogSci 2007) (pp. 1331–1336). Hillsdale: Erlbaum.
Nielsen, T. A. (1992). A self-observational study of spontaneous hypnagogic imagery using the upright napping procedure. Imagination, Cognition and Personality, 11, 353–366.
Nielsen, T. A. (2000a). A review of mentation in REM and NREM sleep: “Covert” REM sleep as a possible reconciliation of two opposing models. The Behavioral and Brain Sciences, 23, 851–866.
Nielsen, T. A. (2000b). Covert REM sleep effects on REM mentation: Further methodological considerations and supporting evidence. The Behavioral and Brain Sciences, 23, 1040–1057.
Nielsen, T. (2007). Felt presence: Paranoid delusion or hallucinatory social imagery? Consciousness and Cognition, 16(4), 975–983.
Nielsen, T. A., McGregor, D., Zadra, A. L., Ilnicki, D., & Ouellet, L. (1993). Pain in dreams. Sleep, 16, 490–498.
Noreika, V., Valli, K., Lahtela, H., & Revonsuo, A. (2009). Early-night serial awakenings as a new paradigm for studies on NREM dreaming. International Journal of Psychophysiology, 74(1), 14–18.
Noreika, V., Windt, J. M., Lenggenhager, B., & Karim, A. A. (2010). New perspectives for the study of lucid dreaming: From brain stimulation to philosophical theories of self-consciousness. Commentary on “The neurobiology of consciousness: Lucid dreaming wakes up” by J. Allan Hobson. International Journal of Dream Research, 3(1), 36–46.
Occhionero, M., Cicogna, P., Natale, V., Esposito, M. J., & Bosinelli, M. (2005). Representation of self in SWS and REM dreams. Sleep & Hypnosis, 7(2), 77–83.
O'Shaughnessy, B. (2002). Dreaming. Inquiry, 45(4), 399–432.
Pagel, J. F. (2003). Non-dreamers. Sleep Medicine, 4, 235–241.
Pagel, J. F., Blagrove, M., Levin, R., States, B., Stickgold, B., & White, S. (2001). Definitions of dream: A paradigm for comparing field descriptive specific studies of dream. Dreaming, 11, 195–202.
Perky, C. W. (1910). An experimental study of imagination. The American Journal of Psychology, 21(4), 422–452.
Raymond, I., Nielsen, T. A., Lavigne, G., & Choinière, M. (2002). Incorporation of pain in dreams of hospitalized burn victims. Sleep, 25, 41–46.
Revonsuo, A. (1995). Consciousness, dreams, and virtual realities. Philosophical Psychology, 8, 35–58.
Revonsuo, A. (2005). The self in dreams. In T. E. Feinberg & J. P. Keenan (Eds.), The lost self: Pathologies of the brain and identity. Oxford: Oxford University Press.
Revonsuo, A. (2006). Inner presence. Consciousness as a biological phenomenon. Cambridge: MIT.
Revonsuo, A., & Salmivalli, C. (1995). A content analysis of bizarre elements in dreams. Dreaming, 5, 169–187.
Schenck, C. H. (2005). Paradox lost. Midnight in the battleground of sleep and dreams. Minneapolis: Extreme Nights.
Schenck, C. H., & Mahowald, M. W. (1996). REM sleep parasomnias. Neurologic Clinics, 14, 697–720.
Schönhammer, R. (2005). Typical dreams. Reflections of arousal. Journal of Consciousness Studies, 12, 18–37.
Schwartz, S. (2000). A historical loop of one hundred years: similarities between 19th century and contemporary dream research. Dreaming, 10, 55–66.
Schwitzgebel, E. (2002a). How well do we know our own conscious experience? The case of visual imagery. Journal of Consciousness Studies, 9(5–6), 35–53.
Schwitzgebel, E. (2002b). Why did we think we dreamed in black and white? Studies in History and Philosophy of Science, 33, 649–660.
Solms, M. (1997). The neuropsychology of dreams: A clinico-anatomical study. New Jersey: Erlbaum.
Solms, M. (2000). Dreaming and REM sleep are controlled by different brain mechanisms. The Behavioral and Brain Sciences, 23, 843–850.
Sosa, E. (2007). A virtue epistemology: Apt belief and reflective knowledge. Oxford: Oxford University Press.
Strauch, I., & Meier, B. (1996). In search of dreams. Results of experimental dream research. Albany: SUNY.
Tholey, P., & Utrecht, K. (2000 [1995]). Schöpferisch Träumen: Wie Sie im Schlaf das Leben meistern. Der Klartraum als Lebenshilfe. Klotz: Eschborn bei Frankfurt am Main.
Windt, J. M. (2010). Altered consciousness in philosophy: An introduction. In E. Cardeña & M. Winkelman (Eds.), Altering consciousness: A multidisciplinary perspective. Westport: Praeger, in press.
Windt, J. M., & Metzinger, T. (2007). The philosophy of dreaming and self-consciousness: What happens to the experiential subject during the dream state? In D. Barrett & P. McNamara (Eds.), The new science of dreaming. Vol 3: Cultural and theoretical perspectives. Westport: Greenwood.
Windt, J. M., & Noreika, V. (2010) How to integrate dreaming into a general theory of consciousness—a critical review of existing positions and suggestions for future research. Consciousness & Cognition, in press.
Wundt, W. (1999 [1897]). Outlines of psychology. Translated by C.H. Judd. Bristol: Thoemmes.
Acknowledgements
I would like to thank Thomas Metzinger, Xenia Paultre and Adrian J.T. Smith as well as an anonymous reviewer for their helpful comments and very constructive criticism on earlier drafts of this paper. This paper was supported by the Barbara-Wengeler Foundation and the Volkswagen Foundation.
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Windt, J.M. The immersive spatiotemporal hallucination model of dreaming. Phenom Cogn Sci 9, 295–316 (2010). https://doi.org/10.1007/s11097-010-9163-1
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DOI: https://doi.org/10.1007/s11097-010-9163-1