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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
- Representation of Number and Magnitude
- The Experience of Embodiment
- The Relation between Space Perception and Emotion
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]
Representation of Number and Magnitude
Number is commonly conceptualised as falling along a mental number line, with small numbers off to the left, and progressively larger numbers to the right. Research in the BodyLab investigates how the representation of number relates to the representation of other types of magnitude information, such as spatial extent or duration. For example, we have found that the same small leftward bias (pseudoneglect) found when people bisect physical lines, also occurs when they 'bisect' number pairs, estimating (without computing) the number midway between two others. Ongoing studies are investigating how such spatial representations of number arise, and how they can be modulated.
In other studies, we have investigated whether common mechanisms underlie the representation of magnitude in different domains, such as number, size, and duration. There is increasing evidence for such a system of general magnitude representation, both in adults and infants.Key papers:
- Longo, M. R., & Lourenco, S. F. (2007). Spatial attention and the mental number line: Evidence for characteristic biases and compression. Neuropsychologia, 45, 1400-1407. [pdf]
- Lourenco, S. F., & Longo, M. R. (2010). General magnitude representation in human infants. Psychological Science, 21, 873-881. [pdf]
The Experience of Embodiment
What is it like to have a body? We are all intimitely familiar with this experience, but its very ubiquity makes it difficult to study, or even to adequately characterise. The development of recent techniques, such as the rubber hand illusion and virtual reality, has allowed experimental manipulation of the experience of embodiment in ways that would previously have been impossible.
Research in the BodyLab investigates the experience of embodiment using these and related techniques. One important question about embodiment is whether it is an indivisible whole, or whether it consists of distinct, dissociable elements. We have found embodiment can, indeed, be decomposed into constituent elements with distinct phenomenology, neural bases, and effects on behaviour. For example, one such dissociation is between the sense of ownership over one's body (the feeling that my body is mine) and the sense of agency over one's body (the feeling that I am in control of my body).Key papers:
- Longo, M. R., Schüür, F., Kammers, M. P. M., Tsakiris, M., & Haggard, P. (2008). What is embodiment? A psychometric approach. Cognition, 107, 978-998. [pdf]
- Longo, M. R., & Haggard, P. (2012). What is it like to have a body? Current Directions in Psychological Science, 21, 140-145. [pdf]
The Relation between Space Perception and Emotion
In everyday life, we face many situations in which we have to react quickly to objects around us. These can be social situations, in which we have to interpret the intentions of people approaching us, or situations in which is required a rapid reaction to rapidly approaching objects, as while driving. A large literature suggests that the brain maintains specialised mechanisms to detect and react to such "looming" objects, on a direct collision course with the observer.
Research in the BodyLab investigates the cognitive and neural bases of detection and response to looming objects. We have found that threat has an impact on looming effect with threatening objects (such as snakes and spiders) judged as arriving sooner relative to non-threatening stimuli (such as rabbitts and butterflies). Interestingly, this effect is modulated by individual characteristics, such as the actual fear of the threatening stimuli. We are now expanding this line of research to include different everyday situations in which the judgment of the arrival time of a stimulus is crucial.Key paper:
- Vagnoni, E., Lourenco, S. F., & Longo, M. R.(2012). Threat modulates perception of looming visual stimuli. Current Biology, 22, R826-R827. [pdf]