Thomas Metzinger

Video ergo sum: Manipulating bodily self-consciousness

Humans normally experience the conscious self as localized within their bodily borders. This spatial unity may break down in certain neurological conditions such as out-of-body experiences, leading to a striking disturbance of bodily self-consciousness. On the basis of these clinical data, we designed an experiment that uses conflicting visual-somatosensory input in virtual reality to disrupt the spatial unity between the self and the body. We found that during multisensory conflict, participants felt as if a virtual body seen in front of them was their own body and mislocalized themselves toward the virtual body, to a position outside their bodily borders. Our results indicate that spatial unity and bodily self-consciousness can be studied experimentally and are based on multisensory and cognitive processing of bodily information.

Motor ontology: the representational reality of goals, actions and selves

The representational dynamics of the brain is a subsymbolic process, and it has to be conceived as an “agent-free” type of dynamical self-organization. However, in generating a coherent internal world-model, the brain decomposes target space in a certain way. In doing so, it defines an “ontology”: to have an ontology is to interpret a world. In this paper we argue that the brain, viewed as a representational system aimed at interpreting the world, possesses an ontology too. It decomposes target space in a way that exhibits certain invariances, which in turn are functionally significant. A challenge for empirical research is to determine which are the functional regularities guiding this decomposition process. What are the explicit and implicit assumptions about the structure of reality, which at the same time shape the causal profile of the brains motor output and the representational deep structure of the conscious mind arising from it (its “phenomenal output”)? How do they constrain high-level phenomena like conscious experience, the emergence of a first-person perspective, or social cognition? By reviewing a series of neuroscientific results, we focus on the contribution the motor system makes to this process. As it turns out, the motor system constructs goals, actions, and intending selves as basic constituents of the world it interprets. It does so by assigning a single, unified causal role to them. Empirical evidence now clearly shows how the brain actually codes movements and action goals in terms of multimodal representations of organism–object relations. Under a representationalist analysis, this process can be interpreted as an internal representation of the intentionality relation itself. We try to show how such a more complex form of representational content, once it is in place, can later function as the building block for social cognition and a for more complex, consciously experienced representation of the first-person perspective as well. The motor system may therefore play a decisive role in understanding how the functional ontology of the human brain could be gradually extended into the subjective and social domains.

Real Virtuality: A Code of Ethical Conduct. Recommendations for Good Scientific Practice and the Consumers of VR-Technology

The goal of this article is to present a first list of ethical concerns that may arise from research and personal use of virtual reality (VR) and related technology, and to offer concrete recommendations for minimizing those risks. Many of the recommendations call for focused research initiatives. In the first part of the article, we discuss the relevant evidence from psychology that motivates our concerns. In section 1.1, we cover some of the main results suggesting that one’s environment can influence one’s psychological states, as well as recent work on inducing illusions of embodiment. Then, in section 1.2, we go on to discuss recent evidence indicating that immersion in VR can have psychological effects that last after leaving the virtual environment. In the second part of the article we turn to the risks and recommendations. We begin, in section 2.1, with the research ethics of VR, covering six main topics: the limits of experimental environments, informed consent, clinical risks, dual-use, online research, and a general point about the limitations of a code of conduct for research. Then, in section 2.2, we turn to the risks of VR for the general public, covering four main topics: long-term immersion, neglect of the social and physical environment, risky content, and privacy. We offer concrete recommendations for each of these ten topics, summarized in Table 1.

Immediate transfer of synesthesia to a novel inducer

In synesthesia, a certain stimulus (e.g. grapheme) is associated automatically and consistently with a stable perceptual-like experience (e.g. color). These associations are acquired in early childhood and remain robust throughout the lifetime. Synesthetic associations can transfer to novel inducers in adulthood as one learns a second language that uses another writing system. However, it is not known how long this transfer takes. We found that grapheme-color associations can transfer to novel graphemes after only a 10-minute writing exercise. Most subjects experienced synesthetic associations immediately after learning a new Glagolitic grapheme. Using a Stroop task, we provide objective evidence for the creation of novel associations between the newly learned graphemes and synesthetic colors. Also, these associations generalized to graphemes handwritten by another person. The fast learning process and the generalization suggest that synesthesia begins at the semantic level of representation with the activation of a certain concept (the inducer), which then, uniquely for the synesthetes, activates representations at the perceptual level (the concurrent). Thus, the results imply that synesthesia is a much more flexible and plastic phenomenon than has been believed until now.

Why are dreams interesting for philosophers? The example of minimal phenomenal selfhood, plus an agenda for future research

This metatheoretical paper develops a list of new research targets by exploring particularly promising interdisciplinary contact points between empirical dream research and philosophy of mind. The central example is the MPS-problem. It is constituted by the epistemic goal of conceptually isolating and empirically grounding the phenomenal property of “minimal phenomenal selfhood,” which refers to the simplest form of self-consciousness. In order to precisely describe MPS, one must focus on those conditions that are not only causally enabling, but strictly necessary to bring it into existence. This contribution argues that research on bodiless dreams, asomatic out-of-body experiences, and full-body illusions has the potential to make decisive future contributions. Further items on the proposed list of novel research targets include differentiating the concept of a “first-person perspective” on the subcognitive level; investigating relevant phenomenological and neurofunctional commonalities between mind-wandering and dreaming; comparing the functional depth of embodiment across dream and wake states; and demonstrating that the conceptual consequences of cognitive corruption and systematic rationality deficits in the dream state are much more serious for philosophical epistemology (and, perhaps, the methodology of dream research itself) than commonly assumed. The paper closes by specifying a list of potentially innovative research goals that could serve to establish a stronger connection between dream research and philosophy of mind.

The myth of cognitive agency: subpersonal thinking as a cyclically recurring loss of mental autonomy

This metatheoretical paper investigates mind wandering from the perspective of philosophy of mind. It has two central claims. The first is that, on a conceptual level, mind wandering can be fruitfully described as a specific form of mental autonomy loss. The second is that, given empirical constraints, most of what we call “conscious thought” is better analyzed as a subpersonal process that more often than not lacks crucial properties traditionally taken to be the hallmark of personal-level cognition - such as mental agency, explicit, consciously experienced goal-directedness, or availability for veto control. I claim that for roughly two thirds of our conscious life-time we do not possess mental autonomy (M-autonomy) in this sense. Empirical data from research on mind wandering and nocturnal dreaming clearly show that phenomenally represented cognitive processing is mostly an automatic, non-agentive process and that personal-level cognition is an exception rather than the rule. This raises an interesting new version of the mind-body problem: How is subpersonal cognition causally related to personal-level thought? More fine-grained phenomenological descriptions for what we called “conscious thought” in the past are needed, as well as a functional decomposition of umbrella terms like “mind wandering” into different target phenomena and a better understanding of the frequent dynamic transitions between spontaneous, task-unrelated thought and meta-awareness. In an attempt to lay some very first conceptual foundations for the now burgeoning field of research on mind wandering, the third section proposes two new criteria for individuating single episodes of mind-wandering, namely, the “self-representational blink” (SRB) and a sudden shift in the phenomenological “unit of identification” (UI). I close by specifying a list of potentially innovative research goals that could serve to establish a stronger connection between mind wandering research and philosophy of mind.

Why are out-of-body experiences interesting for philosophers?: The theoretical relevance of OBE research

After decades of only sparse scientific interest, we are currently witnessing a renaissance of empirical research into out-of-body experiences (OBEs) and full-body illusions. Being a philosopher of mind, I obviously have only a limited judgment of how good this research actually is from a purely scientific point of view. What I can do, however, is to draw attention to a series of theoretical aspects that make OBEs a particularly relevant target of investigation in the ongoing search for the neural correlate of self-consciousness and in the wider context of an empirically grounded theory of the human mind. Firstly, and most basically, this type of research has a great potential for conceptual differentiation. By more clearly distinguishing different types of neurological disorders affecting the sense of self, it will help to improve the taxonomy of selfrelated disorders. Introducing more fine grained conceptual distinctions will have diagnostic, and perhaps also therapeutic value, because it contributes to our taxonomy of hallucinations and deviant forms of self-modeling (see Metzinger, 2003, chapter 7) involving dimensions like ‘‘self-location’’ and ‘‘selfidentification’’. The four main types are autoscopic hallucination, heautoscopy, OBE, and the feeling of a presence – all due to multisensory disintegration and damage to temporo-parietal and temporo-occipital cortex (Blanke and Mohr, 2005; Blanke and Castillo, 2007). Autoscopic phenomena show that not only identification with and localization of body parts, but also of the global conscious representation of the entire body can be disturbed. In autoscopic hallucinations and heautoscopy patients see a second own illusory body in extrapersonal space, but the two phenomena differ in terms of self-identification

Unconscious integration of multisensory bodily inputs in the peripersonal space shapes bodily self-consciousness

Recent studies have highlighted the role of multisensory integration as a key mechanism of self-consciousness. In particular, integration of bodily signals within the peripersonal space (PPS) underlies the experience of the self in a body we own (self-identification) and that is experienced as occupying a specific location in space (self-location), two main components of bodily self-consciousness (BSC). Experiments investigating the effects of multisensory integration on BSC have typically employed supra-threshold sensory stimuli, neglecting the role of unconscious sensory signals in BSC, as tested in other consciousness research. Here, we used psychophysical techniques to test whether multisensory integration of bodily stimuli underlying BSC also occurs for multisensory inputs presented below the threshold of conscious perception. Our results indicate that visual stimuli rendered invisible through continuous flash suppression boost processing of tactile stimuli on the body (Exp. 1), and enhance the perception of near-threshold tactile stimuli (Exp. 2), only once they entered PPS. We then employed unconscious multisensory stimulation to manipulate BSC. Participants were presented with tactile stimulation on their body and with visual stimuli on a virtual body, seen at a distance, which were either visible or rendered invisible. We found that participants reported higher self-identification with the virtual body in the synchronous visuo-tactile stimulation (as compared to asynchronous stimulation; Exp. 3), and shifted their self-location toward the virtual body (Exp.4), even if stimuli were fully invisible. Our results indicate that multisensory inputs, even outside of awareness, are integrated and affect the phenomenological content of self-consciousness, grounding BSC firmly in the field of psychophysical consciousness studies.

Grounding the self in action

Consciousness and cognition are phenomena that seem to be inextricably bound to an individual first-person perspective: at least in standard situations, there is not only conscious experience, but also an experiencing self. And there is not only thought as such, but a thinking self as well. Why is there not only the flow of experience, but also someone—someone who has these experiences? And why do most thoughts not just occur in a free-floating way, like clouds in the sky, but seem to originate from—and within—a thinking self, a self somehow mentally portrayed as an independent cause in itself, a cognitive agent? Presently, in a number of different disciplines, two general answers seem to slowly emerge. First, the subject of consciousness and the subject of thought are frequently present in the unfolding process of phenomenal experience and cognition. They are present in the form and content of a self-representation, i.e., a representation of the experiencing, thinking system as a whole, which can be more or less explicit, more or less accessible to introspection, and more or less conscious. This self-representation is central to any understanding of the deep structure of mind. Second, the theoretically most relevant aspect of phenomenal and cognitive self-representation is likely to be found in the aspect of agency. It has to do with action control. The experience of agency is of maximal importance in constituting a first-person perspective as well as in the development of empathy and social cognition. This is so, because selfhood is not only characterized by phenomenal and representational properties, but also by highly specific functional properties—properties that somehow turn biological organisms into agents, sometimes even into persons. In order to fully understand these functional properties we need to know more about how they are implemented: neurobiologically, behaviorally, and socially. And we need a truly

How does the brain encode epistemic reliability? Perceptual presence, phenomenal transparency, and counterfactual richness

Abstract Seth develops a convincing and detailed internalist alternative to the sensorimotor-contingency theory of perceptual phenomenology. However, there are remaining conceptual problems due to a semantic ambiguity in the notion of “presence” and the idea of “subjective veridicality.” The current model should be integrated with the earlier idea that experiential “realness” and “mind-independence” are determined by the unavailability of earlier processing stages to attention. Counterfactual richness and attentional unavailability may both be indicators of the overall processing level currently achieved, a functional property that normally correlates with epistemic reliability. Perceptual presence as well as phenomenal transparency express epistemic reliability on the level of conscious processing.