Mavi Sánchez-Vives: “In 20 seconds we can produce the illusion of ownership of a third arm”

March 19th, 2014 No Comments

On Tuesday 25 March Mavi Sánchez-Vives, ICREA research professor at the August Pi i Sunyer Biomedical Research Institute (IDIBAPS) will give a lecture titled “Brain and Virtual Reality“, the third in the ICREA-CCCB series of debates on “The Brain”. We have interviewed her in order to learn more about how the neurosciences use this cutting-edge technology.

La professora d’investigació ICREA Mavi Sánchez-Vives

What is your field of research?
I’m a neuroscientist and I use virtual reality as a tool for understanding brain functions. I’ll be speaking at the CCCB about a phenomenon that illustrates very well how expressive the brain is, and our great capacity for transforming the inner representation of our body in very short periods of time. We have different ways of knowing that the representation of our own body is in the brain, one of which is through bodily illusions, which are relatively easy to evoke, for example assigning ownership to a rubber arm. There are also numerous illusions of body transformations described in the literature, some of them known to be caused by certain brain lesions which bring about strange or bizarre alterations, as happens with people who believe they have a third arm, or have out-of-body experiences, or with the cases described by Oliver Sacks, for example the man who thinks that a leg in the bed isn’t his and he wants to be rid of it, and other such extreme cases. By means of virtual reality we can study the limits of representation of our own body by re-creating these illusions without needing to turn to people with brain lesions.

How do you use virtual reality?
Through virtual reality, we can bring about the illusion of ownership of an external body and achieve other such illusions by inducing a series of correlated stimuli which produce these illusions of transformation in very brief periods of time. In twenty or thirty seconds we can produce the illusion of ownership of a third arm by means of virtual reality, for example. The fact that these illusions can be produced so quickly leads us to think that the brain has this enormous expressiveness, and that virtual transformations pave the way for very different kinds of applications.

When you speak of virtual reality, do you mean a headset with a screen?
We speak of immersive virtual reality, with a headset, when the user sees an avatar instead of his or her normal body. These experiments have potential in many areas such as rehabilitation, training, physiotherapy and leisure activities.

What have you discovered, for example?
In the case of rehabilitation, we’re studying treatment of pain. For instance, we have published several papers showing that the colour in which a virtual arm appears to you can affect your pain threshold. If your virtual arm is red, you’re going to be more sensitive to a painful or hot stimulus, while if it’s another colour, blue for example, you’ll be less sensitive to a painful or hot stimulus. This means that the pain threshold is not stable and it can be modified depending on the visual information you receive.

These transformations can be brought about in a virtual environment but also by giving life to a robot.
Yes, body transformations can also happen if, instead of having a virtual body, one incorporates a robot body, and this robot body can be situated some distance away. I can use a virtual environment in Barcelona and see through the eyes of a robot in London, and interact and speak in that environment, so that I have a body in the place of destination. If this becomes general, such practice will have to be legislated, with new laws being passed to stipulate who is responsible in the other place, which might be on the other side of the world.

In this video from the TV programme Quèquicom you can see how a Barcelona-based journalist uses virtual reality to “beam” herself into an office in London in the guise of a robot in order to interview the scientist Mel Slater.

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