The Senses of Agency and Ownership: A Review

Abstract

Usually, we do not question that we possess a body and act upon the world. This pre-reflective awareness of being a bodily and agentive self can, however, be disrupted by different clinical conditions. Whereas sense of ownership (SoO) describes the feeling of mineness toward one's own body parts, feelings or thoughts, sense of agency (SoA) refers to the experience of initiating and controlling an action. Although SoA and SoO naturally coincide, both experiences can also be made in isolation. By using many different experimental paradigms, both experiences have been extensively studied over the last years. This review introduces both concepts, with a special focus also onto their interplay. First, current experimental paradigms, results and neurocognitive theories about both concepts will be presented and then their clinical and therapeutic relevance is discussed.

Keywords: alien hand syndrome; asomatognosia; limb-ownership; phenomenal transparency; rubber hand illusion; sense of agency; sense of ownership; virtual reality therapy.

FIGURE 1

The classical rubber hand illusion. The participant’s hidden hand (lower shelf) and rubber hand (upper shelf) are synchronously stroked by the experimenter. In most participants this induces an illusory SoO over the rubber hand.

FIGURE 2

The intentional binding paradigm. Participants judge the time interval between a voluntary action (e.g., a button press) and its sensory outcome (e.g., an occuring sound). A typical outcome is that participants subjectively underestimate the actual time interval between action onset and sensory outcome (Moore and Obhi, 2012).

FIGURE 3

A simplified illustration of the comparator system. (Adapted from: David et al., 2008).

FIGURE 4

The active rubber hand illusion. The participant’s index finger and artificial index finger are connected via a small rod (dashed line). As a result, whenever the participant moves his or her own index finger up or down, or alternatively the rod is moved up or down by the experimenter, the artificial hand’s index finger moves correspondingly. The occurrence of SoO and SoA can be systematically investigated by varying the mode of agent (i.e., whether the artificial finger movements are self-generated or generated by the experimenter) and by the positioning of the artificial hand (Braun et al., 2014; Kalckert and Ehrsson, 2014a,b).