Showing posts with label RECONSIDER. Show all posts
Showing posts with label RECONSIDER. Show all posts

Artificial Intelligence - What Is A Group Symbol Associator?



Firmin Nash, director of the South West London Mass X-Ray Service, devised the Group Symbol Associator, a slide rule-like device that enabled a clinician to correlate a patient's symptoms against 337 predefined symptom-disease complexes and establish a diagnosis in the early 1950s.

It resolves cognitive processes in automated medical decision-making by using multi-key look-up from inverted files.

The Group Symbol Associator has been dubbed a "cardboard brain" by Derek Robinson, a professor at the Ontario College of Art & Design's Integrated Media Program.

Hugo De Santo Caro, a Dominican monk who finished his index in 1247, used an inverted scriptural concordance similar to this one.

Marsden Blois, an artificial intelligence in medicine professor at the University of California, San Francisco, rebuilt the Nash device in software in the 1980s.

Blois' diagnostic aid RECONSIDER, which is based on the Group Symbol Associator, performed as good as or better than other expert systems, according to his own testing.

Nash dubbed the Group Symbol Associator the "Logoscope" because it employed propositional calculus to analyze different combinations of medical symptoms.

The Group Symbol Associator is one of the early efforts to apply digital computers to diagnostic issues, in this instance by adapting an analog instrument.

Along the margin of Nash's cardboard rule, disease groupings chosen from mainstream textbooks on differential diagnosis are noted.

Each patient symptom or property has its own cardboard symptom stick with lines opposing the locations of illnesses that share that property.

There were a total of 82 sign and symptom sticks in the Group Symbol Associator.

Sticks that correspond to the state of the patient are chosen and entered into the rule.



Diseases with a higher number of symptom lines are thought to be diagnoses.

Nash's slide rule is simply a matrix with illnesses as columns and properties as rows.

Wherever qualities are predicted in each illness, a mark (such as a "X") is inserted into the matrix.

Rows that describe symptoms that the patient does not have are removed.

The most probable or "best match" diagnosis is shown by columns with a mark in every cell.

When seen as a matrix, the Nash device reconstructs information in the same manner as peek-a-boo card retrieval systems did in the 1940s to manage knowledge stores.

The Group Symbol Associator is similar to Leo J. Brannick's analog computer for medical diagnosis, Martin Lipkin and James Hardy's McBee punch card system for diagnosing hematological diseases, Keeve Brodman's Cornell Medical Index Health Questionnaire, Vladimir K.

Zworykin's symptom spectra analog computer, and other "peek-a-boo" card systems and devices.

The challenge that these devices are trying to solve is locating or mapping illnesses that are suited for the patient's mix of standardized features or attributes (signs, symptoms, laboratory findings, etc.).

Nash claimed to have condensed a physician's memory of hundreds of pages of typical diagnostic tables to a little machine around a yard long.

Nash claimed that his Group Symbol Associator obeyed the "rule of mechanical experience conservation," which he coined.



"Will man crumble under the weight of the wealth of experience he has to bear and pass on to the next generation if our books and brains are reaching relative inadequacy?" he wrote.

I don't believe so.

Power equipment and labor-saving gadgets took on the physical strain.

Now is the time to usher in the age of thought-saving technologies" (Nash 1960b, 240).

Nash's equipment did more than just help him remember things.

He asserted that the machine was involved in the diagnostic procedure' logical analysis.

"Not only does the Group Symbol Associator represent the final results of various diagnostic classificatory thoughts, but it also displays the skeleton of the whole process as a simultaneous panorama of spectral patterns that correlate with changing degrees of completeness," Nash said.

"For each diagnostic occasion, it creates a map or pattern of the issue and functions as a physical jig to guide the mental process" (Paycha 1959, 661).

On October 14, 1953, a patent application for the invention was filed with the Patent Office in London.

At the 1958 Mechanization of Thought Processes Conference at the National Physical Laboratory (NPL) in the Teddington region of London, Nash conducted the first public demonstration of the Group Symbol Associator.

The NPL meeting in 1958 is notable for being just the second to be held on the topic of artificial intelligence.

In the late 1950s, the Mark III Model of the Group Symbol Associator became commercially available.

Nash hoped that when doctors were away from their offices and books, they would bring Mark III with them.

"The GSA is tiny, affordable to create, ship, and disseminate," Nash noted.

It is simple to use and does not need any maintenance.

Even in outposts, ships, and other places, a person might have one" (Nash 1960b, 241).

Nash also published instances of xerography (dry photocopying)-based "logoscopic photograms" that obtained the same outcomes as his hardware device.

Medical Data Systems of Nottingham, England, produced the Group Symbol Associator in large quantities.

Yamanouchi Pharmaceutical Company distributed the majority of the Mark V devices in Japan.

In 1959, Nash's main opponent, Fran├žois Paycha, a French ophthalmologist, explained the practical limits of Nash's Group Symbol Associator.

He pointed out that in the identification of corneal diseases, where there are roughly 1,000 differentiable disorders and 2,000 separate indications and symptoms, such a gadget would become highly cumbersome.

The instrument was examined in 1975 by R. W. Pain of the Royal Adelaide Hospital in South Australia, who found it to be accurate in just a quarter of instances.


Jai Krishna Ponnappan


You may also want to read more about Artificial Intelligence here.



See also: 


Computer-Assisted Diagnosis.


Further Reading:


Eden, Murray. 1960. “Recapitulation of Conference.” IRE Transactions on Medical Electronics ME-7, no. 4 (October): 232–38.

Nash, F. A. 1954. “Differential Diagnosis: An Apparatus to Assist the Logical Faculties.” Lancet 1, no. 6817 (April 24): 874–75.

Nash, F. A. 1960a. “Diagnostic Reasoning and the Logoscope.” Lancet 2, no. 7166 (December 31): 1442–46.

Nash, F. A. 1960b. “The Mechanical Conservation of Experience, Especially in Medicine.” IRE Transactions on Medical Electronics ME-7, no. 4 (October): 240–43.

Pain, R. W. 1975. “Limitations of the Nash Logoscope or Diagnostic Slide Rule.” Medical Journal of Australia 2, no. 18: 714–15.

Paycha, Fran├žois. 1959. “Medical Diagnosis and Cybernetics.” In Mechanisation of Thought Processes, vol. 2, 635–67. London: Her Majesty’s Stationery Office


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