Homeostat

The homeostat is one of the first devices capable of adapting itself to the environment. It exhibited behaviours such as habituation, reinforcement and learning through its ability to maintain homeostasis in a changing environment. It was built by William Ross Ashby in 1948 at Barnwood House Hospital.

After a few technical hiccups with short-circuits causing burn-outs, the homeostat was finally completed on 16 March 1948.^[1] It was an adaptive ultrastable system, consisting of four interconnected Royal Air Force bomb control units^[2] with inputs, feedback, and magnetically driven, water-filled potentiometers. It illustrated his law of requisite variety^[3] — automatically adapting its configuration to stabilize the effects of any disturbances introduced into the system. The object of control is the angular deviation from the central position of four magnets, one atop each unit. If perturbed, the magnets return from their displaced position back to their homeostatic position with customizable stability or even instability, depending on the choices of circuit and structural parameters.^[4]

In 1946, Ashby described the design of the units thus "Its principle is that it uses multiple coils in a milliammeter & uses the needle movement to dip in a trough carrying a current, so getting a potential which goes to the grid of a valve, the anode of which provides an output current."^[5] It was the realization of what he had described in 1946 as an "Isomorphism making machine".^[6]

When Alan Turing heard of Ashby's intention to build the homeostat, he wrote to Ashby to suggest that he could run a simulation on Turing's Automatic Computing Engine (ACE) instead of building a special machine.^[7]

The first published account of the homeostat appeared under the title of "Design for a Brain" in the December 1948 issue of 'Electronic Engineering',^[8] where he speculates about a perfected homeostat that could eventually play chess "with a subtlety and depth of strategy beyond that of the man who designed it."

In 1949 Time described it as "the closest thing to a synthetic brain so far designed by man".^[9]

En 1952, Ashby lo demostró en la novena conferencia Macy sobre cibernética . ^{[ 10 ]} Ese mismo año publicó una descripción del homeostato en su influyente libro Diseño para un cerebro . En total, entre 1946 y 1967, escribió 38 entradas sobre el homeostato en su diario. ^{[ 11 ]}

En su biografía en línea de Ashby, ^{[ 6 ]} Jill Ashby escribió sobre el homeostato: "En 1961, Ross se lo llevó consigo al Laboratorio de Computación Biológica de la Universidad de Illinois y lo dejó allí cuando se jubiló en 1970. Aparentemente, se dañó poco después cuando se inundó la zona donde se guardaba".

• teoría de sistemas

• Haug, Hallvard (20 de abril de 2016). "La máquina pensante: W. Ross Ashby y el homeostato" . Blog de ciencia de la Biblioteca Británica . Recuperado el 13 de julio de 2026 .
• El archivo digital de W. Ross Ashby incluye una biografía, bibliografía, cartas, fotografías, películas e imágenes totalmente indexadas de las 7.189 páginas de la revista de Ashby, compuesta por 25 volúmenes.
• W. Ross Ashby (1956): Introducción a la cibernética , (Chapman & Hall, Londres): disponible en formato PDF , Principia Cybernetica Web, 1999.
• Homeostato en la Web Principia Cybernetica .