Sunday, July 27, 2008


From the blog of the Futurepundit, Randall Parker: it appears that Nature does what engineers are taught to do- hide complexity.
Decisions flow from the properties of the materials our bodies are made of and their interactions with the environment. When we pick up an object, we are able to hold it not primarily because of what our brain says but because our soft hands mold themselves around the object automatically, increasing surface contact and therefore frictional adhesion. When a cockroach encounters an irregular surface, it does not appeal to its brain to tell it what to do next; instead, its musculoskeletal system is designed so that local impacts drive its legs to the right position to take the next step.
The biologist who discovered this last fact, Joseph Spagna, currently at the University of Illinois, teamed up with engineers at the University of California at Berkeley to build a robot inspired by nature. The result, named RHex (for its six legs), is a robot that can traverse varied terrain without any central processing at all. At first it had a lot of trouble moving across wire mesh with large, gaping holes. Spagna’s team made some simple, biologically inspired changes to the legs of the robot. Without altering the control algorithms, they simply added some spines and changed the orientation of the robot’s feet, both of which increased physical contact between the robot and the mesh. That was all it took to generate the intelligence required for the device to move ahead. In a related project, Iida and his MIT group are now building legs that operate with as few controlled joints and motors as possible, an engineering technique they call underactuation.
I am impressed just that it can walk across such a mesh.

Another post from the same blogs describes how nature employs the "need to know" principle. The eye is fooled by optical illusions, but the Hand is not
Ben-Gurion University of the Negev Psychologist Tzvi Ganel and his colleagues presented research participants with the “Ponzo” illusion, an image common in psychological research that makes two objects that are similar in length appear drastically different. They then hooked participants’ index finger and thumb to computerized position tracking equipment and asked them to grasp the objects with their fingers.

Even thought the object appeared to be larger (or smaller) than it really was, the size of their grasp reflected the object’s real rather than apparent size. For good measure, the researchers arranged the illusion so that the object that appeared to be the smaller of the two was actually the larger of the two.
More evidence for the existence of the two visual pathways which I first read of in VS Ramachandran's book
According to this view, put forward more than a decade ago by Mel Goodale and David Milner, one system, -- vision-for-perception -- gives us our conscious visual experience of the world, allowing us to see objects in the rich context of the scenes in which they are embedded. It’s also the one that is fooled by optical illusions.

The other system, vision-for-action, provides the visual control we need to move about and interact with objects. This system does not have to be conscious, but does have to be quick, goal-directed, and accurate - and as a consequence, is much less likely to be fooled by illusions such as the one used by Ganel and his colleagues.

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