With the emergence of virtual and augmented reality (VR, AR, XR, collectively *R) technologies, the capabilities of Nozick’s ‘experience machine’ thought experiment are within our grasp. *R allows for first-person experiences that seem real, enabling us to view situations from other perspectives and providing opportunities for innovative therapeutic benefits such as confronting phobias, pain management, and anxiety disorders, whilst also being useful for military and medical training (Slater et al., 2020).
However, although *R allows for a degree of realism, some suspension of disbelief is still required. That is, although experiences in *R seem real, they do not feel real. While *R allows for a degree of visual immersion, it cannot yet deliver all of the physical sensations associated with interacting with the real world. Our sense of immersion is immediately and abruptly interrupted when we, for example, reach to touch something but cannot actually feel it. The next logical step in virtual realism, therefore, is to facilitate the sense of tactile, touch sensation – haptic technology.
We outline three ways in which touch plays a particular role in our sense of immersion, presence, and realism. That touch (1) facilitates our sense of agency; (2), complements and confirms our other sensory modalities (such as vision); and (3) provides privileged information that corresponds to our sense of self and body ownership. We also consider the limitations that current haptic technology – such as the use of haptic gloves and other devices – has in delivering realism and identify future research agendas.
An important implication of Nozick’s experience machine is its illustration that we seem to value real experiences over virtual ones. However, although we might not value touch-enabled *R experiences as much as real experiences, they clearly still matter to some degree. Regardless of their source, for example, they will still evoke real emotions. The implications of tactile realism for consciousness science, therefore, are particularly important because digital touch technology raises several ethical concerns.
We identify the key concerns as tactile unreliability, tactile selfhood, and tactile autonomy respectively. First, because touch provides an ultimate arbiter of presence in the real physical world, we ought to be cautious about how digital touch disrupts our ordinary understanding of touch’s confirmatory role. As an example, we consider ‘tactile deepfakes’ and how these might produce particularly problematic experiences. Second, touch is deeply involved with key aspects of self-consciousness such as bodily self-awareness and agency. Touch technologies could generate the experience of trying to touch your own body but finding nothing there. We suggest that this could provoke a crisis of self-consciousness. Third, a distinctive feature of our sensory experiences is the degree of autonomous control we have over them. Although touch is "always on" (and perhaps because it is always on) we carefully control what (and particularly who) we allow to touch us. Tactile technologies risk individuals being subjected to unwanted experiences, with implications for both autonomy and privacy.