Machine and Thought: The Turing Test
Instructor: Viola Schiaffonati
April, 7th 2016
Machines and thought
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The dream of intelligent machines
The philosophical-scientific tradition
The ‘official’ birth of Artificial Intelligence (1956)
“The study is to proceed on the basis of the conjecture that
every aspect of learning or any other feature of intelligence
can in principle so precisely described that a machine can be
made to simulate it” (McCarthy 1955)
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To start
Turing test as starting point
Computing Machinery and Intelligence (1950)
The imitation game and possible objections
Some references to the following debate
Even if they are not all explicitly discussed in Turing’s paper,
they derive from it
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To continue
Two possible interpretations for the Turing test
Original Imitation Game Test, Standard Turing test
Consequences in evaluating intelligence
Open issues
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Can machines think?
Problem of definition
Machine
Thought
No single answer
Question substituted with
another question, connected to
the first one and not ambiguous
New form of the problem
described as a game
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The imitation game
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Three players
A man (A), a woman (B), and an interrogator (C)
C stays in a room apart from A and B that C knows only
as X and Y
C has to determine which of the other two is the man and
which is the woman just by means of questions
A’s object: to try and cause C to make the wrong
identification
B’s object: to help the interrogator
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The Turing test
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“Can machines think?” replaced by
“What will happen when a machine takes the part of A in
this game? Will the interrogator decide wrongly as often
when the game is played like this as he does when the
game is played between a man and a woman?”
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Why a new question?
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Is this new question a worthy one to investigate?
Precise criterion for success
Sharp line between physical and intellectual capacities
Question and answer method suitable for introducing
almost any one of the fields of human endeavor that we
wish to include
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Machines concerned in the game
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Whether there are imaginable computers which would do
well in the game
Digital computers
Able to carry out any operation which could be done by a
human computer
The human computer is supposed to be following fixed rules
Discrete-state machines
Store, executive unit, control
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Considering again the question
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“Can machines think?” replaced by
“Are there imaginable digital computers which would do
well in the imitation game? Let us fix our attention on one
particular digital computer C. Is it true that by modifying
this computer to have an adequate storage, suitably
increasing its speed of action, and providing it with an
appropriate programme, C can be made to play
satisfactorily the part of A in the imitation game, the part
of B being taken by a man?”
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Turing’s answer
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“I believe that in about fifty years’ time it will be possible
to programme computers […] to make them play the
imitation game so well that an average interrogator will
not have more that 70 per cent chance of making the
right identification after five minutes of questioning”
Importance of conjectures for suggesting useful lines of
research
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Some objections
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Arguments from various disabilities
Machines can make all, except X
Turing: skepticism deriving from the idea of machines able
to do only repetitive tasks
Lady Lovelace’s objection
Machines can never do anything really new or surprising
Turing: machines take me by surprise because I do not do
sufficient calculation to decide what to expect them to do
Mathematical objection
Limits to the capacities of state-discrete machines (Gödel
1931, Turing 1937)
Turing: same limits could hold for human reasoning as well
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Learning machines
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How to program machines able to do well in the imitation
game?
Evolutionary learning
Punishments and rewards method
Which are the best fields to start with? Abstract or
concrete activities?
Both approaches
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Turing’s two tests for intelligence
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Sterrett (2000)
Original Imitation Game test
Standard Turing Test
Turing presented them as equivalent, Sterrett claims they
are not equivalent
It is the first, neglected, test that provides a more
appropriate indication of intelligence
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The two tests (Sterrett 2000)
ORIGINAL IMITATION GAME
TEST
What will happen when a machine
takes the part of A in this game? Will
the interrogator decide wrongly as
often when the game is played like
this as he does when the game is
played between a man and a woman?”
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STANDARD TURING TEST
Are there imaginable digital computers
which would do well in the imitation
game? Is it true that […] can one build a
particular computer to play satisfactorily
the part of A in the imitation game, the
part of B being taken by a man?”
Original imitation game test
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Test structure permits the result that the machine does
better than the man
There is nothing inherent in the game to prevent the machine
from scoring higher than the man
Test tends to screen off lack of interrogator skill
Since the machine’s intelligence is measured by comparing
the frequency with which it succeeds in causing the
interrogator to make the wrong identification with the
frequency with which a man does so, the results will not be
too sensitive to the skill of the interrogator
Both man and machine are required to impersonate. The
machine’s performance is not directly compared to the
man’s, but their rates of successfully impersonating against
a real woman candidate are compared
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Standard Turing test
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No meaningful result could indicate that the machine does
better than the man
What test result would indicate that the machine had
outperformed the human, give that the criterion is simply
giving a performance indistinguishable from a human’s?
Test results are very sensitive to the interrogator’s skills
or lack of skill
The machine’s fortune in passing the test will go up and
down with the skill level of the interrogator
Only the computer is attempting to impersonate. The
computer’s performance is judged based on similarity to a
man’s performance
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Intellectual abilities and cognitive habits
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Better characterization of intelligence with the Original
Imitation Game Test
To fool the interrogator C, better cognitive abilities are
required
A must impersonate a woman and induce to make C the
wrong identification (both in the case A is a man and in the
case A is a machine)
This requires the ability to evaluate the adequacy of own
answers
Impersonation requires higher intellectual abilities
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Some advantages?
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To diminish the man’s advantage in the game
The test focuses on a notion of machine intelligence,
rather than similarity to human
Critical cognitive capacities are emphasized, whereas
habitual behaviors are de-emphasized
Difference between a response requiring thought and a
response that, though entirely appropriate, is habitual
To de-emphasize training and emphasize thinking
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Consequences
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Intelligence intended in a more general meaning, not
merely as human intelligence
It is not required to have lived a human like life
The original imitation Game Test extracts a supercritical
kind of thought from humans, and then uses it to
construct a measure by which the machine’s capabilities
can be measured
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References
Sterrett, S. (2000) “Turing's Two Tests for Intelligence”,
Minds and Machines 10, 541-59.
Turing, A. (1950) “Computing machinery and
intelligence”, Mind 59, 433-460.
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