CHAPTER 27

The Turing test—from

every angle

diane proudfoot

C

an machines think? Turing’s famous test is one way of determining the answer. On

the sixtieth anniversary of his death, the University of Reading announced that a

‘historic milestone in artificial intelligence’ had been reached at the Royal Society:

a computer program had passed the ‘iconic’ Turing test. According to an organizer, this

was ‘one of the most exciting’ advances in human understanding. In a frenzy of worldwide

publicity, the news was described as a ‘breakthrough’ showing that ‘robot overlords creep

closer to assuming control’ of human beings. Yet after only a single day it was claimed that

‘almost everything about the story is bogus’: it was ‘nonsense, complete nonsense’ to say that

the Turing test had been passed. The program concerned ‘actually got an F’ on the test. The

backlash spread to the test itself; critics said that the ‘whole concept of the Turing Test is kind

of a joke . . . a needless distraction’.^1 So, what is the Turing test—and why does it matter?

A little experiment

In 1948, in a report entitled ‘Intelligent machinery’, Turing described a ‘little experiment’ that,

he said, was ‘a rather idealized form of an experiment I have actually done’. It involved three

subjects, all chess players. Player A plays chess as he/she normally would, while player B is

proxy for a computer program, following a written set of rules and working out what to do using

pencil and paper—this ‘paper machine’ was the only sort of programmable computer freely

available in 1948 (see Ch. 31). Both of these players are hidden from the third player, C. Turing

said, ‘Two rooms are used with some arrangement for communicating moves, and a game is

played between C and either A or the paper machine’. How did the experiment fare? According

to Turing, ‘C may find it quite difficult to tell which he is playing’.^2 This is the first version of what

has come to be known as ‘Turing’s imitation game’ or the ‘Turing test’.