One of the huge problems in developing self-propelled robots is awareness of the body positioning. We as humans and animals have that solved very well – we sense when we touch something and are very aware of the boundaries of our physical selves. But how – is sense of touch absolutely critical for that?
Scientists the UK and the United States showed that when the sense of touch is lost humans use other senses to accurately position and move their bodies.
Sense of touch is very important for us to understand the boundaries of our physical selves. Image credit: Weldis via Wikimedia (CC BY-SA 3.0)
Sometimes people lose their senses – you definitely know about deafness and blindness, but other senses may be lost as well. Scientists worked with Ian and Kim, who have no sense of touch. In fact, Ian lost his tactile sense and the sense of body position below his neck after an illness in teenage years. Meanwhile Kim was born without sensory nerve fibres needed to feel her body.
Obviously, knowing where exactly your body is at is very important so that you wouldn’t walk into obstacles and would know when you are getting hurt. So how did Kim and Ian adapt to their condition?
Scientists invited Ian, Kim and several controls to a lab to participate in a series of experiments. For example, they had to report on the shape and size of their hands by moving a cursor on a screen to locate landmarks like fingertips and knuckles. Kim, who was born without somatosensation, uses vision, hearing, and the vestibular system to understand her position in space. Ian is a different case, because he had the sense of touch and lost it. However, their performance in these tests were very similar. Both of them were fairly accurate in their estimations of their hands – not that different from the control group.
However, their performance was a bit different due to the fact that Kim had her lifetime to adapt, while Ian had to consciously learn to compensate for his disability. Chris Miall, lead researcher of the study, said: “We think the differences between Ian’s and Kim’s responses relate to the visual control that both of them use to navigate their environment. For Ian, this is a very conscious process and he has learned to use visual cues to continually evaluate and monitor that environment. For Kim the process is much more unconscious. She still uses the visual information, but in a more instinctive and intuitive way”.
Although it is not as common as blindness or deafness, loss of a sense of touch is debilitating. It can be quite dangerous, because body positioning becomes very tricky. However, the human body is amazing and people learn to adapt. Understanding those mechanisms may help rehabilitation efforts for those who lost their sense of touch as adults.
Source: University of Birmingham