What turns an information processing living thing into something which experiences? What is this entity having these experiences? Why there is always someone having the experiences?
It turns out that the experience of being a self—of being “someone” rather than “something” is not just an abstract idea. It is inextricably rooted in having and inhabiting a physical body. This is known as Bodily Self-Consciousness (BSC).
Bodily self-consciousness is a multidimensional construct made up of several independent components.
Sense of Ownership (SoO) is the pre-reflective experience that your body and its parts “belong to me”. It is the physical feeling of “mineness”.
Sense of Agency (SoA) is the experience of being the owner and initiator of your own actions. While ownership is about having a body, agency requires action and is inherently temporal.
Peripersonal Space (PPS)is your invisible forcefield around your body. It is the multisensory, action-centered space immediately surrounding your body, extending roughly to an arm’s length.
Interoception is the brain’s representation of the body’s internal physiological state, which functions as an increasingly recognized component that predicts and modulates the other three constructs.
How We Test the Self in the Lab
To study something as subjective as the “self,” researchers have developed clever experimental paradigms to manipulate these constructs. The Rubber Hand Illusion (RHI) is the dominant paradigm for investigating the Sense of Body Ownership. By synchronously stroking a participant’s hidden real hand and a visible rubber hand, researchers can induce an illusory sense of ownership over the fake hand. Intentional Binding tests the implicit Sense of Agency. It measures the subjective temporal compression between a voluntary action (like pressing a key) and its sensory consequence (like hearing a tone). Audio-Tactile Facilitation is used to map Peripersonal Space. Participants are tested on how rapidly they can detect a weak tactile stimulus on their hand while an auditory or visual stimulus is simultaneously presented near or far from their body.
Understanding these constructs completely transforms how we view clinical conditions. When components of the bodily self are disrupted, the clinical presentations are striking. Schizophrenia (The Porous Self) presents with a multifaceted disruption of bodily self-consciousness. Patients often experience a loss of natural self-evidence and a severe reduction in their sense of agency. This manifests directly in “passivity symptoms” where a patient feels that their actions or thoughts are externally caused.
Autism Spectrum Disorder (The Rigid Self) is characterized by a comparatively rigid, proprioceptively-anchored bodily self. Multiple independent laboratories have reported that autistic individuals show reduced susceptibility to the Rubber Hand Illusion compared to matched neurotypical controls. This rigidity appears to stem from elevated interoceptive precision, which attenuates the influence of external visual inputs.
PTSD (The Invaded Self). Trauma produces lasting changes in how the brain processes bodily signals. PTSD fundamentally alters the sense of agency, interoception, and peripersonal space. Patients typically fall into two distinct profiles - the hyperarousal subtype, where the body becomes a hyper-vigilant threat-detection system, or the dissociative subtype, which is marked by diminished interoceptive awareness and somatic disconnection.
Depersonalisation/Derealisation Disorder (DPD) is characterized by a profound, non-delusional sense of detachment from one’s body, thoughts, and environment. Patients often describe feeling like they are in a bubble or separated from the world by a pane of glass.