I guess one should not forget Chess.
While today classified as 'Weak AI' and seen as branch of 'Game AI', playing chess was in prior times always seen as a pinnacle of human capabilities and automated chess play thus a major proof of machine intelligence.
Within a limited scenario (3 piece end game) this was already practically shown by the Spanish El Ajedrecista, an electro-mechanical special purpose computer, in 1912. It received world wide fame - way before anyone coined the term KI or AI (*1).
Naturally chess was as well in after war world of emerging computers long seen as a major goal for archiving higher functions - not at least due it's clear defined nature enabling a definitive proof of achievement. A good overview how early attempts to archive such is layed out in Claude Shannons 1950 paper
XXII. Programming a Computer for Playing Chess. A title that already points into the direction taken early on.
In this paper he ranks the achievements as follow:
This paper is concerned with the problem of constructing a computing routine or
"program" for a modern general purpose computer which will enable it to play chess. Although perhaps of no practical importance, the question is of theoretical interest, and it is hoped that a satisfactory solution of this problem will act as a wedge in attacking other problems of a similar nature and of greater significance. Some possibilities in this direction are: -
- (1) Machines for designing filters, equalizers, etc.
- (2) Machines for designing relay and switching circuits.
- (3)Machines which will handle routing of telephone calls based on the individual circumstances rather than by fixed patterns.
- (4)Machines for performing symbolic (non-numerical) mathematical operations.
- (5)Machines capable of translating from one language to another.
- (6)Machines for making strategic decisions in simplified military operations.
- (7)Machines capable of orchestrating a melody.
- (8)Machines capable of logical deduction.
It is believed that all of these and many other devices of a similar nature are possible developments in the immediate future. The techniques developed for modern electronic and relay type computers make them not only theoretical possibilities, but in several cases worthy of serious consideration from the economic point of view.
One can't help noting how low language translation was rated. It does shed light on the complete different evaluation of complexity back then, doesn't it? Important for this question might be that Shannon did not write this as a mere abstract contemplation, but based on his knowledge of Computers already existing and in development.
While that paper was a strictly theoretical venue, not much after first programs to solve certain chess problems were developed. Theoretical, like Turing did as early as 1951, or more practical by Dietrich Prinz, who was a major contributor to the Mark 1, implementing the Mate-in-two problem as well in 1951. By 1957 a full chess has been implemented by IBM on the 704. The rest is improvement thereon.
The important point here is that all of those steps, from Quevedo chess player all the way to Deep Blue's win in 1997, were seen at that time as incredible signs of machine intelligence - and reported as such.
*1 - AI seems to be a direct translation of German Künstliche Intelligenz - as several early English reports of the late 1940s early 1950s on that topic do use the German term.