Guided Self-organization
Growing an ear out of iron...
In the middle of the 20th century, cyberneticists Stafford Beer and Gordon Pask performed a series of investigations, where they tried to use one complex and poorly understood natural system to control another complex and poorly understood system. This research was remarkably exploratory, and at times quite outlandish! One of the most fantastic results, reported on at a conference by Pask, was their growth of an artificial "ear." This was an artificial electromechanical system that could distinguish between different sounds, but it wasn't designed and constructed by hand, it was produced by selectively varying the voltage applied to electrodes placed in a solution of ferrous sulphate (see Figure 1) so as to grow a system that performed the desired function!
The details are unfortunately lost to history, but presumably the essential concept was that increasing voltage stabilizes the randomly grown structures, and decreasing in voltage would cause existing structures to dissolve. Pask and Beer could use this to "reward" (i.e. stabilize) those structures that serve their desired purpose (tone discrimination) and "punish" (i.e. destroy) structures that are non-functional. How precisely this could construct a functional system and how efficient such a physically-instantiated evolutionary process is remains unclear, and is the subject of one branch of this research project, where we set out to recreate Pask's Ear.
First steps...
Pask's Ear is essentially a dissipative structure, an inherently unstable system that persists thanks to the dissipation of usable energy, in this case electricity. Resarchers at the University of Connecticut have constructed a less complex, but still very interesting system that also uses electric potential to create interesting dissipative structures. This system essentially consists of a petri-dish containing some mineral oil and ball-bearings. Around the edge of the petri dish is a circular grounded electrode and a couple of inches above the dish is a high-voltage electrode. When the current is turned on, the ball-bearings self-organize into dendritic trees, in a way that is somewhat similar to the systems studied by Pask and Beer (see Figure 2). As a first step towards recreating Pask's work, we are building a similar system to that instantiated at UConn here at the University of Auckland.
References
Figure 1. Photograph of dendritic structures grown by applying voltage to electrodes in a solution of ferrous sulphate. When an electric current is applied to electrodes placed in the solution, iron precipitates out of solution forming dendritic filiments. Pask and Beer were able to selectively reward the growth of certain structures and not others, resulting in the growth of a system capable of distinguishing between two stimulus sounds. For more information, see the article that this was taken from: P. Cariani. To evolve an ear. Epistemological implications of gordon pask's electrochemical devices. Systems research 10.3 (1993): 19-33.
Figure 2. Self-organized ball-bearing-based dendritic structures. This is fascinating work carried out at UConn. This photo is a grab from the video in the supplementary information of the following article: Dilip Kondepudi, Bruce Kay, and James Dixon End-directed evolution and the emergence of energy-seeking behavior in a complex system. Phys. Rev. E 91.