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Research Projects in the BodyLabResearch in the BodyLab investigates a wide range of issues relating to the representation of the human body and its effects on perception and cognition. This page describes a few of the lines of research ongoing in the lab.
- Body Representations Underlying Perception
- The Perception of Near Space
- Pain and the Body
- The Experience of Extra Body Parts
Body Representations Underlying Perception
Several aspects of perception require that incoming sensory signals be referenced to information about the body. This need is especially acute in somatosensation, in which the primary sensory surface - the skin - is spatially coextensive with the body.
Research in the BodyLab investigates how body representations mediate several aspects of somatosensory perception, including where on the body one is touched, how big the objects are, and where our limbs are in external space. We have found that in many cases, the brain appears to use highly distorted representations of body size and shape. Intriguingly, these representations appear to preserve distortions known to characterise brain maps in the somatosensory cortex (e.g., the Penfield homunculus).
In contrast, when people explicitly judge what their body is like, their responses are generally accurate. This dissociation suggests that somatosensation relies on a class of implicit body representations, distinct from the conscious body image. Ongoing research in the BodyLab is further investigating implicit and explicit body representations, and the factors that shape them.Key papers:
- Longo, M. R., & Haggard, P. (2010). An implicit body representation underlying human position sense. Proceedings of the National Academy of Sciences, USA, 107, 11727-11732. [pdf]
- Longo, M. R., Long, C., & Haggard, P. (2012). Mapping the invisible hand: A body model of a phantom limb. Psychological Science, 23, 740-742. [pdf]
The Perception of Near SpaceSeveral lines of evidence demonstrate that the brain maintains specialised representations of the space immediately surrounding the body, distinct from the representation of more distant space. Research in the BodyLab investigates how we represent this near or peripersonal space.
In one line of studies, we are investigating the plasticity of near space representations. On the one hand, the size of near space expands when we use a tool, suggesting that the tool is incorporated as part of the body. On the other hand, the size of near space contracts when we wear heavy weights on our wrist, which make it more difficult to act. Together, these studies demonstrate that the representation of near space is highly plastic, flexibly expanding and contracting to facilitate whatever task we are presently engaged in.
Near space is not infinitely plastic, however. In addition to the high degree of flexibility, we have also found consistent individual differences which relate systematically to body size. For example, people with longer arms have a correspondingly larger near space surrounding their body. Recently, we have also begun to investigate how the representation of near space may be involved in our emotional reactions to events around us. We have found, for instance, that people with a larger near space report increased claustrophobic fear.Key papers:
- Longo, M. R., & Lourenco, S. F. (2006). On the nature of near space: Effects of tool use and the transition to far space. Neuropsychologia, 44, 977-981. [pdf]
- Lourenco, S. F., Longo, M. R., & Pathman, T. (2011). Near space and its relation to claustrophobic fear. Cognition, 119, 448-453. [pdf]
Pain and the Body
Painful sensations are almost invariably localised to specific parts of the body. Increasing evidence suggests that our experience of pain is connected in important ways with the way in which we represent the body itself. For example, we have found that simply seeing one's body reduces the subjective experience of acute pain, and associated brain processes, even when the vision is entirely non-informative about stimulation. Further, distorting the visual experience of the body with magnifying and minifying mirrors modulated this effect, increasing it and decreasing it, respectively.
Ongoing research in the BodyLab is investigating the psychological and neural bases of this visually induced analgesia, using a combination of neural and behavioural techniques.Key papers:
- Longo, M. R., Betti, V., Aglioti, S. M., & Haggard, P. (2009). Visually induced analgesia: Seeing the body reduces pain. Journal of Neuroscience, 29, 12125-12130. [pdf]
- Longo, M. R., Iannetti, G. D., Mancini, F., Driver, J., & Haggard, P. (2012). Linking pain and the body: Neural correlates of visual analgesia. Journal of Neuroscience, 32, 2601-2607. [pdf]
The Experience of Extra Body Parts
The representation of our body is very flexible, allowing us to feel an altered perception of our bodies with multisensory illusions or Virtual Reality. Recent studies show we can also feel extra body parts as part of our own body. A research question that arises is how supernumerary body parts are represented in our brain.
At the BodyLab, we developed a new technique that enabled the sixth finger illusion to remain for a long duration, which suggests an endured representation of the supernumerary finger. It is unclear if supernumerary body parts are represented as a copy of our body parts or independently. For instance, patients with supernumerary phantom limb syndrome feel like they have a duplicated limb, with the same size and shape of the existing one. Using the sixth finger illusion, we have found that the illusory supernumerary finger can be represented independently, with its own features. We can feel a long and a short sixth finger, with a different length from our actual fingers.
Ongoing research in the BodyLab is investigating the embodiment of bodily properties using the sixth finger illusion.Key papers:
- Cadete, D., & Longo, M. R. (2020). A continuous illusion of having a sixth finger. Perception, 49, 807–821. [pdf]
- Cadete, D., & Longo, M. R. (2022). The long sixth finger illusion: The representation of the supernumerary finger is not a copy and can be felt with varying lengths. Cognition, 218, 104948. [pdf]