Measure the success in terms of fidelity to human performance.

Definition exists between two approaches:

1] A Human Centered Approach.

2] A Rationalist Approach.

1] A human centered approach must be empirical science involving hypothesis and experimental confirmation.

2] A rationalist approach involves a combination of mathematics and engineering.

1] Acting humanly: The Turing test approach, The Turing test, proposed by Alan Turing in 1950, was designed to provide a satisfactory operational definition of intelligence satisfactory operational definition of intelligence. in AI Turing test is method of inquiry for determining whether or not a computer is capable of thinking like a human being.

Example Imagine a game of three players having two humans and one computer, and interrogator (as human) is isolated from other two players.

The interrogator job is to try and figure out which one is human and which one is computer by asking questions from both of them. To make the things harder computer is trying to make the interrogator guess wrongly.

Here, player C, the interrogator is given the task of trying to determine which player A or B – is a computer and which is a human.

The conversation between interrogator and computer would be like this,

C (Interrogator) : Are you a computer?

A : NO

C : Multiply one large no to another, 158745887 * 56755647

A : After a long pause, an incorrect answer !

C : Add 5478012, 4563145

A : (Pause 20 sec and then give answer)

100 41157.

If integrator would not be able to distinguish the answer's provided by both human and computer then the computer passes the test and machine (computer) is considered as intelligent as human.

2] Thinking humanly: The cognitive modeling approach.

Cognitive modeling is an area of computer science that deals with simulating human problem solving and mental processing in a computerized model. Such a model can be used to simulate or predict human behavior or performance on tasks similar to the ones modeled and improve human computer interaction. It is used in numerous Ag application such as expert systems, natural language, processing, neural networks, in robotics and virtual reality application.

If we are going to say that a given program thinks like a human, we must have some way of determining how humans think. We need to get inside the actual working of human minds.

There are two ways to do this:

Through Introspection – Trying to catch our own thoughts as they go by and through psychological experiment. Once we have sufficiently precise theory of theory of mind, it becomes possible to express the theory as a computer program. If the programs input/output and timing behaviors match corresponding human behavior, that is evidence that some of the programs mechanisms could also be operating in humans.

3] Thinking rationally: The laws of thought approach, the Greek Philosopher. Aristotle was one of the first to attempt to codify “right thinking” that is irrefutable reasoning processes. His syllogisms provided patterns for argument structures that always yielded correct conclusions when given correct premises.

Example: “Socrates is man, all men are mortal. therefore, Socrates is mortal.”

These law of thought were supposed to govern the operation of the mind. Their study initiated the field called logic.

4] Acting rationally: The Rational Agent Approach. An agent is just something that acts. But computer agents are expected to have other attributes that distinguish them from mere “program” such as operating under autonomous control, perceiving their environment, persisting over a prolonged time. Period, adapting to change and being capable of taking on another's goals. A rational agent is one that acts so as to achieve the best outcome or when there is uncertainty, the best expected outcome.