Wallwork, S. B., Bellan, V., Catley, M. J., & Moseley, G. L. (2016). Neural Representations and the Cortical Body Matrix: Implications for Sports Medicine and Future Directions. Br. J. Sports Med.
50, 990–996. doi: 10.1136/bjsports-2015-095356 Several recent studies have shown relationships between Weber`s illusion and body representations. Taylor-Clarke and colleagues (2004), for example, used magnification or reduction of a video image to create the visual experience of the participant`s forearm, which was zoomed in or out. They found corresponding changes in the perceived distance between contacts on the forearm, which increased after enlargement and decreased after minimization. Similarly, de Vignemont, Ehrsson and Haggard (2005) used tendon oscillation to create the illusion that the participant`s finger had expanded in length, analogous to the Pinocchio illusion described above. This illusion led to a corresponding increase in the perceived distance between the keys applied to this finger. Finally, Bruno and Bertamini (2010) induced the illusion of the rubber hand with hands of different sizes and found that the perceived size of gripping objects was increased after experiencing the illusion with a larger hand. How our brain represents our body has been an interesting topic in the field of neuropsychology and neuroscience for many years (Lhermitte, 1942). In this regard, the sense of embodiment (or physical self), that is, the feeling of having a body (Gallagher, 2000), arises from a complex interaction between ascending sensory signals and top-down cognitive processes that take place in a bodily setting (Longo et al., 2008; Tsakiris, 2017). Specifically, it has been described that the meaning of incarnation consists of several structurally different subjective components: (1) property, (2) agency, and (3) self-location (Longo et al., 2008; Kilteni et al., 2012a). In fact, a fundamental component of incarnation is the sense of bodily responsibility (Tsakiris, 2017).
The feeling of bodily ownership is described as the perception of one part of the body or the whole body that belongs to it (Ehrsson, 2020). The feeling of the ability to act, that is, the feeling of being the initiator or source of the body`s actions, is another fundamental part of the incarnation (Gallagher, 2000). Moreover, from a conceptual point of view, the meaning of incarnation is built around the first-person pronoun (Gallagher, 2012), in which the subject feels localized in a physical body itself (Lenggenhager et al., 2006). The perceptual distinction between what is part of one`s own body and what is not is a crucial factor for human perception, action, and cognition (Ehrsson, 2020). Second, the meaning of incarnation is multisensory in nature and depends on how all the different sensory modalities come together to form a coherent perception of one`s own body or body part (Ehrsson, 2020). Proske, U., & Gandevia, S. C. (2012). Proprioceptive senses: Their role in signaling body shape, body position and movement, and muscle strength. Physiological Reviews, 92, 1651-1697. Recent studies have shown that somatosensory treatment is based on a class of implicit representations of the body that have large distortions in size and shape.
The link between these representations and conscious body image remains unclear. Dissociations have been reported in the clinical literature on eating disorders between different measures of body image, with larger and more consistent biases found in pictorial measures in which participants compare their body to a visual representation of a body than metric measures in which participants compare their bodies to a non-corporeal norm. Here, we compared the underlying implicit body representations in the sense of position with the body image measured using pictorial and metric methods. Body image was measured using a mapping method (model matching), in which participants assessed whether their hand was wider or thinner than a hand image shown, and a metric method (line length), in which participants assessed whether different parts of their hand were shorter or longer than a line presented. Consistent with the previous results, characteristic biases were found for the implicit representation of the underlying body in the sense of position. These distortions were also found in attenuated form for metric but unrepresentative body image measurements. Although these results reproduce the fundamental dissociation between implicit body representations and conscious body image, they show that this dissociation is not absolute and that specific tasks can use both to varying degrees depending on the requirements of the task. Metric measurements may not be pure measures of body image, but a combination of visual and somatosensory representations of the body. Riva, G. (2008). From the virtual body to the real body: virtual reality as embodied technology. J.
Cyber Ther. Rehabilitation. 1, 7–22. In the present study, we wanted to investigate the influence of goal-based teaching and goal-achievement feedback on updating body representation, using the visuo-motor version of the rubber hand paradigm. Intentional movements are very common in everyday life.