Introduction to Artificial Intelligence

Artificial IntelligenceSection 4

Mr. Sciame

Definitions

• Artificial Intelligence is the ability of a machines to do things that people would say require intelligence.

• AI research is an attempt to discover and describe aspects of human intelligence that can be simulated by machines.

What Computers Can Do

• Play games– And learn from them

• Learn to recognize visual or auditory patterns

• Find proofs for mathematical theorems• Solve certain, well formulated kinds of

problems• Process information expressed in

human languages

Basic Goal of AI Research

• To construct a machine that exhibits the behavior associated with human intelligence (comparable to the intelligence of a human being).– The machine does not have to use the same

underlying mechanisms used in human cognition.– The machine does not have to go through stages

of development and learning such as those through which people progress.

Alan Turing• Alan Turing proposed an

operational test of intelligence as a replacement for the philosophical question, "Can machines think?" Variations of this test have been used to assess performance levels of many AI programs.

• Turing's contributions to mathematics, computer science and early AI extend well beyond his seminal paper proposing the test.

The Turing Test

• In the Turing test, a judge has conversations (via teletype) with two systems, one human, the other a machine.

• The conversations can be about anything, and proceed for a set period of time (e.g., an hour).

• If, at the end of this time, the judge cannot distinguish the machine from the human on the basis of the conversation, then Turing argued that we would have to say that the machine was intelligent.

Diagram of Turing Test

Comments on Turing Test

1. The interrogator does not observe the physical nature of the subjects; only the intellectual behavior is observed.

1. Can it fry an egg?2. Either a machine will pass the Turing test, or a valid

proof that no machine can pass it will be found.1. Therefore, no such machine can be constructed.

3. What if more than 1 machine passes the Turing Test?1. A general description then must be made.

4. If created, there would be a machine that surpasses human intelligence

Straight from Miriam-Webster• in·tel·li·gence • Pronunciation: \in-ˈte-lə-jən(t)s\ • Function: noun • Etymology: Middle English, from Middle French, from Latin

intelligentia, from intelligent-, intelligens intelligent Date: 14th century

• (1): the ability to learn or understand or to deal with new or trying situations : reason ; also : the skilled use of reason (2): the ability to apply knowledge to manipulate one's environment or to think abstractly as measured by objective criteria (as tests)

• B Christian Science : the basic eternal quality of divine Mind c: mental acuteness : shrewdness

Continued Miriam-Webster

• 2 a: an intelligent entity ; especially : angel • b: intelligent minds or mind <cosmic intelligence>• 3: the act of understanding : comprehension• 4 a: information , news • b: information concerning an enemy or possible

enemy or an area ; also : an agency engaged in obtaining such information

• 5: the ability to perform computer functions

Natural Intelligence

• To summarize the definitions on the last two slides, intelligence is the ability to “act rightly in a given situation.”

• An AI computer can make mistakes, but can also change its behavior and stop making mistakes.

Human Intelligence

• Limited, but can learn and improve performance in certain tasks.

• While there are “Intelligence Tests”, little is known concerning the limitations to intelligence.– These tests predict little concerning the

development of a person’s intelligence; particularly what problems a person can solve.

Evidences of Human Intelligence

• Comes from 4 sources:– History– Introspection– The Social Sciences– The Biological Sciences

History

• There is too much to discuss here in this class– People who claim the ancients were

smarter (navigation)– The letter writing during the Civil War– People who look at all we have/done and

say we’re the smartest generation.

Introspection

• “I think, therefore I exist.” Rene Descartes

• He felt:– Animals not much different from machines.– People are different from animals since

they communicate effectively– “The ability to use languages is the most

significant indication that something has human intelligence.”

Introspection and Nonintellectual Learning

• Some notions of nonintellectual learning:1. Subconscious Learning – Knowledge

obtained without conscious reasoning.2. Emotional Learning – Knowledge

perceived as an emotion.3. Inspired Learning – Given

instantaneously (by some deity).4. Paradoxical Learning – Perceiving

knowledge that is self contradictory.

Introspective Introspection

• If some intelligence cannot be explained logically or scientifically:– There is some knowledge computers cannot possess, and

some ways of gaining knowledge that computers can’t use.– Is there spiritual learning? If so, should our definition of AI

change to learning some forms of intelligence (and not all)

• The irony: Introspection is probably the source most commonly used in artificial intelligence research for information about specific problem-solving abilities of human intelligence.

Social Sciences

• What we know:1. Human intelligence is species-wide.2. Intelligence of an individual develops

with time and is strongly affected by the nature of its environment.

3. Intelligence is strongly influenced by heredity.

4. Intelligence varies with respect to different problem domains (aptitudes)

Piaget’s Findings

• A child’s intelligence develops in stages– We don’t know precisely why…– These stages do exist.– Each child must accumulate sufficient experience

within a stage before progressing to the next.

• Piaget distinguished 4 stages:1.Sensory-motor2.Preoperational3.Concrete Operational4.Formal Operational

Sensory-Motor Stage

• From birth to age 2• The child goes from using only

instincts to an elementary ability to reason and use signals.

• Examples:– Depth Perception– Cause and effect (It rattles when you

shake it)– Vocal and body gestures

Preoperational Stage

• From age 2 to 7• The child learns:– Basic Vocabulary– Expresses ideas in sentences (not single

words)– Reading and writing begin towards the

end of this stage.

Concrete-Operational Stage

• From age seven to eleven• Can start to judge (Which glass has

more water).

Formal Operations Stage

• From age 11 upward• Can operate logically• Can plan experiments to increase

knowledge• Reasons abstractly

Biological Science

• Some discussion must be given to the human nervous system:– The brain– The neuron (pictured to

the left)

The Human Brain

Typical Brain Sitting Next to You