Jessica Hobson

This essay addresses Cartesian duality and how its implicit dialectic might be repaired using physics and information theory. Our agenda is to describe a key distinction in the physical sciences that may provide a foundation for the distinction between mind and matter, and between sentient and intentional systems. From this perspective, it becomes tenable to talk about the physics of sentience and ‘forces’ that underwrite our beliefs (in the sense of probability distributions represented by our internal states), which may ground our mental states and consciousness. We will refer to this view as Markovian monism, which entails two claims: (1) fundamentally, there is only one type of thing and only one type of irreducible property (hence monism). (2) All systems possessing a Markov blanket have properties that are relevant for understanding the mind and consciousness: if such systems have mental properties, then they have them partly by virtue of possessing a Markov blanket (hence Markovian). Markovian monism rests upon the information geometry of random dynamic systems. In brief, the information geometry induced in any system—whose internal states can be distinguished from external states—must acquire a dual aspect. This dual aspect concerns the (intrinsic) information geometry of the probabilistic evolution of internal states and a separate (extrinsic) information geometry of probabilistic beliefs about external states that are parameterised by internal states. We call these intrinsic (i.e., mechanical, or state-based) and extrinsic (i.e., Markovian, or belief-based) information geometries, respectively. Although these mathematical notions may sound complicated, they are fairly straightforward to handle, and may offer a means through which to frame the origins of consciousness.

We would like to thank Dolega and Dewhurst for a thought-provoking and informed deconstruction of our article, which we take as applause from valued members of our audience. In brief, we fully concur with the theatre-free formulation offered by Dolega and Dewhurst and take the opportunity to explain why we used the Cartesian theatre metaphor. We do this by drawing an analogy between consciousness and evolution. This analogy is used to emphasize the circular causality inherent in the free energy principle. We conclude with a comment on the special forms of active inference that may be associated with selfawareness and how they may be especially informed by dream states.

This paper considers the Cartesian theatre as a metaphor for the virtual reality models that the brain uses to make inferences about the world. This treatment derives from our attempts to understand dreaming and waking consciousness in terms of free energy minimization. The idea here is that the Cartesian theatre is not observed by an internal audience but furnishes a theatre in which fictive narratives and fantasies can be rehearsed and tested against sensory evidence. We suppose the brain is driven by the imperative to infer the causes of its sensory samples; in much the same way as scientists are compelled to test hypotheses about experimental data. This recapitulates Helmholtz's notion of unconscious inference and Gregory's treatment of perception as hypothesis testing. However, we take this further and consider the active sampling of the world as the gathering of confirmatory evidence for hypotheses based on our virtual reality. The ensuing picture of consciousness resolves a number of seemingly hard problems in consciousness research and is internally consistent with current thinking in systems neuroscience and theoretical neurobiology. In this formalism, there is a dualism that distinguishes between the process of inference and the process that entails inference. This separation is reflected by the distinction between beliefs and the physical brain states that encode them. This formal approach allows us to appeal to simple but fundamental theorems in information theory and statistical thermodynamics that dissolve some of the mysterious aspects of consciousness

Dreaming consciousness can be quite different from waking consciousness and this difference must depend upon the underlying neurobiology. Our approach is to infer the underlying brain basis for this difference by studying dream reports and comparing them with waking. In this study we investigated mentation during dreaming by asking subjects to provide us with dream reports and by asking them to create a dream log. In the dream log, the subjects recorded all implausibility, illogicality or inappropriateness of character during the dream narrative when compared to the character’s real-life waking counterpart. Thus, the dream acted as its own control in comparing waking and dreaming mentation

What is dreaming, and what causes it? Why are dreams so strange, and why are they so hard to remember? Replacing dream mystique with modern dream science, J. Allan Hobson provides a new and increasingly complete picture of how dreaming is created by the brain. Dreaming explores how the new science of dreaming is affecting theories in psychoanalysis, and how it is helping our understanding of the causes of mental illness. Through an investigation of his own dreams to illustrate and explain some of the fascinating discoveries of modern sleep science, Hobson challenges some of the traditionally accepted theories about the meaning of dreams and reveals why sleep is not just good for health but essential for life.

Sleep researchers in different disciplines disagree about how fully dreaming can be explained in terms of brain physiology. Debate has focused on whether REM sleep dreaming is qualitatively different from nonREM (NREM) sleep and waking. A review of psychophysiological studies shows clear quantitative differences between REM and NREM mentation and between REM and waking mentation. Recent neuroimaging and neurophysiological studies also differentiate REM, NREM, and waking in features with phenomenological implications. Both evidence and theory suggest that there are isomorphisms between the phenomenology and the physiology of dreams. We present a three-dimensional model with specific examples from normally and abnormally changing conscious states. Key Words: consciousness; dreaming; neuroimaging; neuromodulation; NREM; phenomenology; qualia; REM; sleep

The studies reported in the following articles are aimed at providing a comprehensive, detailed, and quantitative picture of cognition in human dreaming. Our main premises are that waking, REM sleep, and non-REM sleep represent physiologically distinct and identifiable brain states and that the differences between waking, REM, and NREM mentation reflect these physiological differences. We have studied dreams at a formal level of analysis and, in these papers, have studied the specific dream properties of emotions, bizarre transformations, scene shifts, and plot coherence, in adults and 4- to 10-year-old children, as part of a larger effort to map state-dependent mental phenomena back onto the varying neurobiological processes that must underlie them. We believe that such efforts will enhance our understanding not only of dreaming and its neurophysiological substrates, but also of the cognitive processes that dreaming shares with other unusual mental states

Consciousness undergoes dramatic and stereotyped changes in parallel with changes in brain state over the sleep‐wake cycle. No change is more striking or more informative than that which differentiates waking and REM sleep dreaming. For example, dreaming is characterized by internally generated perceptions, by false beliefs, by cognitive impairments, by emotional intensification, and by amnesia. When they occur in waking, these formal state features characterize what is called mental illness. Because the underlying changes in brain state are well described, it is possible to create a model which links the formal features of the mental state to changes in brain physiology and chemistry. The resulting synthesis of conscious state phenomenology and brain neurophysiology provides a solid foundation for mind‐body integration in both normal and abnormal conditions.

In this paper, a new method of quantitatively assessing continuity and discontinuity of visual attention is developed. The method is based on representing narrative information using graph theory. It is applicable to any type of narrative report. Since dream reports are often described as bizarre, and since bizarreness is partially characterized by discontinuities in plot, we chose to test our method on a set of dream data. Using specific criteria for identifying and arranging objects of visual attention, dream narratives from 10 subjects were obtained and mapped onto graphs. The interrater reliabilities were 76% and 91% . Discontinuities in visual attention were quantified by plotting transitions from one part of a graph to another, which provided a spatiotemporal map of attention shifts within a narrative. This procedure was compared with other approaches to discontinuity and also applied to a set of 10 fantasy reports from the same subjects. The results showed that our method includes but transcends other approaches and has the capability to distinguish dream and fantasy reports. To our knowledge, the method provides the most rigorous and reliable measure to date of continuity and discontinuity of attention in narrative reports

A novel "dream splicing" technique allows the objective evaluation of thematic coherence in dreams. In this study, dream reports were cut into segments and segments randomly recombined to form spliced reports. Judges then attempted to distinguish spliced reports from intact ones. Five judges correctly scored 22 spliced and intact reports 82% of the time ; 13 of the 22 reports were correctly scored by all five judges . We conclude that most dream reports contain sufficient coherence to allow judges to distinguish intact from spliced reports. In contrast, abridged reports, which had all but their first and last five lines removed, were correctly identified in only 10 of 38 reports, suggesting that thematic continuity does not normally extend from the beginning to the end of dreams. The continuity identified in this minority of the reports depended on easily identifiable features, such as specific characters, objects, locations, and emotions, rather than on "latent" themes

The "Nightcap," a relatively nonintrusive and "user-friendly" sleep monitoring system, was used by 11 subjects on 10 consecutive nights in their homes. Eighty-eight sleep mentation reports were obtained after spontaneous awakenings from Nightcap-identified REM sleep and 61 were obtained from NREM awakenings. Sleep mentation was recalled in 83% of REM reports and 54% of NREM reports. The median length of REM reports was 148 words compared to 21 words for NREM reports. Twenty-four percent of the REM reports were over 500 words long; no NREM reports over 500 words were obtained. REM report lengths were lowest during the first 15 min of the REM cycle and longest 15–45 min into the period. In contrast, 7 of the 9 NREM reports more than 100 words long occurred within the first 15 min of NREM periods. The Nightcap thus appears to be an effective and efficient method of collecting large numbers of sleep mentation reports with correlated sleep staging under normal ecological conditions

The nature and time course of sleep onset mentation was studied in the home environment using the Nightcap, a reliable, cost-effective, and relatively noninvasive sleep monitor. The Nightcap, linked to a personal computer, reliably identified sleep onset according to changes in perceived sleepiness and the appearance of hypnagogic dream features. Awakenings were performed by the computer after 15 s to 5 min of sleep as defined by eyelid quiescence. Awakenings from longer periods of sleep were associated with an increase in reported sleepiness, a decrease in the length of mentation reports, a decrease in the frequency of reports of normal, wake-like thoughts, an increase in the frequency of “unusual thoughts,” and increased frequencies of formal dream features, including visual hallucination, self-representation, fictive movement, narrative plot, and bizarreness. While sleep-onset reports can include all features of rapid eye movement dream reports, the number of such features is markedly reduced at sleep onset, suggesting that this mentation is a greatly diminished version of REM dreaming

To extend the hypothesis that bizarre discontinuities in dreams result from the interaction of chaotic, "bottom-up" brainstem activation with "top-down" cortical synthesis, we have performed a detailed analysis of dream discontinuities using a new methodology that allows for objective characterization of this formal dream feature. Transformations of characters and objects in dream reports were found to follow definite associational rules. While there were 11 examples of character–character transformation and 7 of inanimate object–inanimate object transformation, transformations of characters into inanimate objects and vice versa were never observed. Judges′ scores on a transformation-matching task further showed that the nature of the transformed character or object is highly constrained by the features of the initial character or object . We conclude that despite the threat to dream coherence posed by bizarre discontinuities, significant coherence is maintained by associational constraints, especially in the case of object and character transformations

We have conducted a home-based study of children′s dream reports in which parents used open-ended interviewing styles to collect 88 dream reports from their 4- to 10-year-old children in the comfortable and supportive environment of their own homes. Particular attention was paid to formal properties including characters , settings, self-representation, and bizarreness. In contrast to previous studies, our data indicate that young children are able to give long, detailed reports of their dreams that share many formal characteristics with adult dream reports. Because this wide range of dream mentation is only revealed to trusted confidants in a familiar and comfortable environment, an important implication is that the sleep laboratory may not be the best source of naturalistic dream data