In an influential article, Olaf Blanke and Thomas Metzinger have set out to isolate the necessary and sufficient conditions of the conscious experience of “being a self”, which they call minimal phenomenal selfhood (MPS; Blanke and Metzinger 2009). MPS is, in their own terms, “the simplest form of self-consciousness”. In their original article, they further defined MPS as “the experience of being a distinct, holistic entity capable of global self-control and attention, possessing a body and a location in space and time” (Blanke and Metzinger 2009, p. 7). Drawing from the empirical data about autoscopic phenomena and full-body illusions, they claimed that global identification with the body as a whole, self-location in space and time and the experience of an oriented visuospatial perspective are the constituting features of MPS, meaning that they are both necessary and sufficient for it. By contrast, they argued that agency and motor control are at best a causally enabling condition for MPS in most humans and animals, but are not necessary for it. Thus, Blanke and Metzinger concluded that self-identification with a body, spatiotemporal self-location and an oriented visuospatial perspective are what constitute at a low level the “subjective” or “perspectival” character of conscious experience, such that it would be impossible to have any kind of self-awareness, as minimal as it may be, without these three aspects.
This hypothesis has been partially challenged by two kinds of empirical data: on the one hand, reports of “bodiless” dreams, in which the dreamer lacks the experience of having a body (Occhionero & Cicogna, 2011); on the other hand, descriptions of “asomatic” OBEs, in which subjects do not appear to self-identify with any bodily form (Alvarado, 2000). In both of these cases, subjects do not seem to lack the experience of “being a self” just because it feels to them as if they did not have a body. Indeed, they still feel that they themselves are present in a specific environment, with a clear sense of the distinction between themselves and the external world; thus, they retain the experience of being a distinct “entity”, although they do not identify with a bodily form. If such an interpretation of these empirical cases is correct, identification of a body as one’s own is not a necessary condition of MPS. Furthermore, even the visual aspect of the visuospatial perspective might not be necessary for MPS, because individuals suffering from congenital blindness can have dreams without any visual component, which are nonetheless structured by mere spatiotemporal presence and spatial orientation. Thus, Jennifer Windt has proposed to reduce MPS to “a purely spatiotemporal [perspective] or sense of self-location” (Windt 2010, p. 313). If this is correct, then the distinction between self-location and (purely spatiotemporal) perspective seemingly breaks down: the “simplest form of self-consciousness” would simply be the experience of being present at a given space and time, maybe with an additional component of (non-visual) spatial orientation. Jakub Limanowski has recently made a similar claim regarding the contingency of body ownership for MPS (Limanowski, 2014).
Taking into account this shortcoming of the original concept of MPS, Thomas Metzinger has since refined his previous account, introducing the notion of the phenomenal unit of identification (UI; Metzinger 2013). He defined the UI as the relatively invariant phenomenal property with which a given subject self-identifies at a given time, generating “the distinct experience of ‘I am this!’”. In ordinary cases, the target properties of self-identification would most likely be “the integrated contents of our current body image”, accompanied by “the subjective quality of ‘agency’ in the control of bodily actions” (p. 5), because we are embodied agents and identify with a body over which we have global control. In bodiless dreams and asomatic OBEs, however, not only do subjects lack the experience of identifying with a body (describing themselves as “pure consciousness”, “balls of light” or “points in space”), but they can also lack agency and motor control. Metzinger thus claims that in some altered states of consciousness, the UI can be something else than the experienced body image, namely either:
- The experienced origin of the visuospatial perspective as an “extensionless point in space”, which he calls the minimal UI—the simplest possible unit of identification.
- The unity of consciousness, or awareness as such, which he calls the maximal UI—the most general phenomenal property available for identification. This might happen in some asomatic OBEs and in deep meditative states in which subjects self-identify with “pure consciousness”.
In a revision of his original account, Metzinger concluded that MPS is constituted by self-identification with at least a minimal UI (and not necessarily with a body), which merely requires spatiotemporal self-location. A paradigmatic phenomenological report of MPS, according to him, would thus be of the form “I am this, here and now”, where “this” is the UI. Even in cases in which the UI appears to be reduced to an extensionless point, the experience is still structured by a subjective perspective linked to this point of origin—whether or not it involves a visual component.
Current questions related to this avenue of research include the following:
Is it correct to say that the simplest and most fundamental kind of self-consciousness (MPS) depends neither upon the identification of a body as mine, nor upon exteroceptive (visuotactile) and somatosensory information, but simply upon the spatiotemporal perspectival structure of experience, associated to an origin point?
Is MPS a necessary condition of consciousness? In other words, can there be conscious experiences lacking an UI, and thus MPS, altogether? Candidate experiences include alleged cases of conscious mentation in deep dreamless sleep (Windt, Nielsen, & Thompson, 2016) and so-called drug-induced ego dissolution (Millière, forthcoming). The case of non-dual awareness in meditation is unclear (Ataria, Dor-Ziderman, & Berkovich-Ohana, 2015; Dor-Ziderman, Berkovich-Ohana, Glicksohn, & Goldstein, 2013), as is the case of acute psychotic episodes in early schizophrenia.
How does MPS relate to the three notions (a)-(c) mentioned in axis 1 and disambiguated by (Guillot, 2016)? Is it really a kind of “self-consciousness”?