Course Overview What is AI? What are the Major Challenges?

Course Overview What is AI? What are the Major Challenges? What are the Main Techniques? Where are we failing, and why? Step back and look at the Science Step back and look at the History of AI What are the Major Schools of Thought? What of the Future? Part I: Introduce you to what’s happening in Artificial Intelligence Done Part II: Give you an appreciation for the big picture  Why it is a grand challenge What are we trying to do How do we do it A lot of people would start with the history – but it’s a bit meaningless at first

Done Course Overview Step back and look at the Science
What is AI? What are the Major Challenges? What are the Main Techniques? Where are we failing, and why? Step back and look at the Science Step back and look at the History of AI What are the Major Schools of Thought? What of the Future? Part I: Introduce you to what’s happening in Artificial Intelligence Done Part II: Give you an appreciation for the big picture  Why it is a grand challenge What are we trying to do How do we do it A lot of people would start with the history – but it’s a bit meaningless at first

Understanding Information Processing Systems
We attribute non-behavioural properties to the system We say that it has a purpose, goals or desires We say that it has internal beliefs and knowledge and competence We attribute meaning to its external behaviour and internal information We treat other humans like this all the time, call it folk psychology Representation: information in the system can represent real things For example: symbols could represent objects and relationships This would allow a clear separation of what and how Alternatively: it could be a messy representation what and how tangled together It has procedures for processing information We call these procedures algorithms in computer speak Describes how it does what it does A clear set of steps that need to be followed Like the recipe for making a cake Like the instructions for long multiplication

We attribute non-behavioural properties to the system We say that it has a purpose, goals or desires We say that it has internal beliefs and knowledge and competence We attribute meaning to its external behaviour and internal information We treat other humans like this all the time, call it folk psychology Representation: information in the system can represent real things For example: symbols could represent objects and relationships This would allow a clear separation of what and how Alternatively: it could be a messy representation what and how tangled together It has procedures for processing information We call these procedures algorithms in computer speak Describes how it does what it does A clear set of steps that need to be followed Like the recipe for making a cake Like the instructions for long multiplication Remember Marr’s What and How?

We attribute non-behavioural properties to the system We say that it has a purpose, goals or desires We say that it has internal beliefs and knowledge and competence We attribute meaning to its external behaviour and internal information We treat other humans like this all the time, call it folk psychology Representation: information in the system can represent real things For example: symbols could represent objects and relationships This would allow a clear separation of what and how Alternatively: it could be a messy representation what and how tangled together It has procedures for processing information We call these procedures algorithms in computer speak Describes how it does what it does A clear set of steps that need to be followed Like the recipe for making a cake Like the instructions for long multiplication What Remember Marr’s What and How? How

We attribute non-behavioural properties to the system We say that it has a purpose, goals or desires We say that it has internal beliefs and knowledge and competence We attribute meaning to its external behaviour and internal information We treat other humans like this all the time, call it folk psychology Representation: information in the system can represent real things For example: symbols could represent objects and relationships This would allow a clear separation of what and how Alternatively: it could be a messy representation what and how tangled together It has procedures for processing information We call these procedures algorithms in computer speak Describes how it does what it does A clear set of steps that need to be followed Like the recipe for making a cake Like the instructions for long multiplication What Representation ties together How

Three Levels in Information Processing Systems (Marr’s three levels)
What What information is coming in? What information is outputted? What is the relationship? (also explains why it’s important) Representation ties together How Procedure/Algorithm – clear set of instructions (how to process the inputoutput) Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

Three Levels in Information Processing Systems
What What information is coming in? What information is outputted? What is the relationship? Interesting: Unlike other sciences we can study top two levels independently from the physical level Representation ties together How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What Caveat: This is a particular philosophical position, called “Functionalism”. Some philosophers do not accept it. What information is coming in? What information is outputted? What is the relationship? Interesting: Unlike other sciences we can study top two levels independently from the physical level Representation ties together How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What Caveat: This is a particular philosophical position, called “Functionalism”. Some philosophers do not accept it. Functionalism: mental states (beliefs, desires, being in pain, etc.) are constituted solely by their functional role; i.e. their causal relations to other mental states, sensory inputs, and behavioural outputs. What information is coming in? What information is outputted? What is the relationship? Interesting: Unlike other sciences we can study top two levels independently from the physical level Representation ties together How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What Caveat: This is a particular philosophical position, called “Functionalism”. Some philosophers do not accept it. Functionalism: mental states (beliefs, desires, being in pain, etc.) are constituted solely by their functional role; i.e. their causal relations to other mental states, sensory inputs, and behavioural outputs. Consequence: a mind can be implemented in lots of different physical hardware, so long as it performs the right functions. What information is coming in? What information is outputted? What is the relationship? Interesting: Unlike other sciences we can study top two levels independently from the physical level Representation ties together How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What’s special about a mind then? We know it can do things a computer can’t do… Three Levels in Information Processing Systems What Caveat: This is a particular philosophical position, called “Functionalism”. Some philosophers do not accept it. Functionalism: mental states (beliefs, desires, being in pain, etc.) are constituted solely by their functional role; i.e. their causal relations to other mental states, sensory inputs, and behavioural outputs. Consequence: a mind can be implemented in lots of different physical hardware, so long as it performs the right functions. What information is coming in? What information is outputted? What is the relationship? Interesting: Unlike other sciences we can study top two levels independently from the physical level Representation ties together How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What’s special about a mind then? We know it can do things a computer can’t do… A Functionalist claims that the special thing about the mind is the special information processing tasks, representations and algorithms it uses Three Levels in Information Processing Systems What Caveat: This is a particular philosophical position, called “Functionalism”. Some philosophers do not accept it. Functionalism: mental states (beliefs, desires, being in pain, etc.) are constituted solely by their functional role; i.e. their causal relations to other mental states, sensory inputs, and behavioural outputs. Consequence: a mind can be implemented in lots of different physical hardware, so long as it performs the right functions. What information is coming in? What information is outputted? What is the relationship? Interesting: Unlike other sciences we can study top two levels independently from the physical level Representation ties together How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What’s special about a mind then? We know it can do things a computer can’t do… A Functionalist claims that the special thing about the mind is the special information processing tasks, representations and algorithms it uses One could implement the same functions in a computer – don’t need organic neurons Three Levels in Information Processing Systems What Caveat: This is a particular philosophical position, called “Functionalism”. Some philosophers do not accept it. Functionalism: mental states (beliefs, desires, being in pain, etc.) are constituted solely by their functional role; i.e. their causal relations to other mental states, sensory inputs, and behavioural outputs. Consequence: a mind can be implemented in lots of different physical hardware, so long as it performs the right functions. What information is coming in? What information is outputted? What is the relationship? Interesting: Unlike other sciences we can study top two levels independently from the physical level Representation ties together How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

Important to Study All Three Levels
What What information is coming in? What information is outputted? What is the relationship? How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What What information is coming in? What information is outputted? What is the relationship? Could have elegant mathematical theory which no algorithm can implement How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What What information is coming in? What information is outputted? What is the relationship? But without top level… Lose sight of what your information processing is trying to achieve How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What What information is coming in? What information is outputted? What is the relationship? Could have a nice algorithm, but might take too much physical hardware to be practical How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

What What information is coming in? What information is outputted? What is the relationship? Focussing on the physical interactions here gives you no idea of what their purpose is How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

Insights from studying the brain could give clues about the algorithms and representations which are (or are not) being used What What information is coming in? What information is outputted? What is the relationship? How Procedure/Algorithm – clear set of instructions Must be physically carried out Man with paper and pen Mechanical computer Modern PC Human brain (neurons) Physical Implementation

Another Perspective on Cognitive Science
Studying different information processing tasks at different levels Vision Language Memory Problem Solving Learning What (Info Proc Task) How (Algorithm) Physical Implementation

AI and Cognitive Science
Two way interaction between AI and Cognitive Science AI informs Cognitive Science Common to implement a cognitive theory in a computer Run the program and see the ramifications of the theory (Scientific hypothesis testing) Running it may be necessary because theory is complicated Also, existing AI theories may shed light on the way humans do it Cognitive Science informs AI Seeking inspiration to solve an AI problem Study the way humans do it Copy in computer …or at least constrain the possible options under consideration

“AI can have two purposes
“AI can have two purposes. One is to use the power of computers to augment human thinking, just as we use motors to augment human or horse power. Robotics and expert systems are major branches of that. The other is to use a computer's artificial intelligence to understand how humans think. In a humanoid way. If you test your programs not merely by what they can accomplish, but how they accomplish it, then you're really doing cognitive science; you're using AI to understand the human mind.” Herbert Simon

Applications of Cognitive Science
Education and Learning From Cognitive Psychology: Diagnose and treat children’s reading difficulties Stroke Therapy From Linguistics: Understanding of speech impairments when stroke in left hemisphere of brain … better therapy Legal process Understanding of reliability of memory Question reliability of legal witnesses Computing Technology From AI: You know loads of examples by now

Cognitive Science – Different Methods
Psychology Philosophy Linguistics Neuroscience Artificial Intelligence / Computer Science

Psychology Controlled laboratory experiments Detailed observations of behaviour Philosophy Linguistics Neuroscience Artificial Intelligence / Computer Science

Psychology Controlled laboratory experiments Detailed observations of behaviour Philosophy Thought experiments Investigate consequences, and coherence of theories Linguistics Neuroscience Artificial Intelligence / Computer Science

Psychology Controlled laboratory experiments Detailed observations of behaviour Philosophy Thought experiments Investigate consequences, and coherence of theories Linguistics Test speakers’ intuitions about “grammatical” sentences Analyse children’s acquisition and errors Neuroscience Artificial Intelligence / Computer Science

Psychology Controlled laboratory experiments Detailed observations of behaviour Philosophy Thought experiments Investigate consequences, and coherence of theories Linguistics Test speakers’ intuitions about “grammatical” sentences Analyse children’s acquisition and errors Neuroscience Study active brain regions when doing something Study neurons Artificial Intelligence / Computer Science

Psychology Controlled laboratory experiments Detailed observations of behaviour Philosophy Thought experiments Investigate consequences, and coherence of theories Linguistics Test speakers’ intuitions about “grammatical” sentences Analyse children’s acquisition and errors Neuroscience Study active brain regions when doing something Study neurons Artificial Intelligence / Computer Science Write programs, see where they succeed and fail

Cognitive Psychology What are the mental processes in between stimulus and response? Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … Motor output sensoryinput

Cognitive Psychology What are the mental processes in between stimulus and response? Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … Motor output sensoryinput (rough model - Boundaries are not clear in reality)

Focus on central unit… Thinking Draw conclusions from facts, solve problems, plan actions… In many diverse domains Attention Helps us focus on some task Has limited capacity Memory (includes Knowledge Representation) Seems to be huge Seems to be no limit on how well it retrieves relevant information Learning Acquire new knowledge and sensorimotor skills How does this central system work?

Physical Symbol System Hypothesis
“A physical symbol system has the necessary and sufficient means of general intelligent action.” therefore… human thinking = symbol manipulation Newell & Simon, 1963.

“A physical symbol system has the necessary and sufficient means of general intelligent action.” Their symbols are taken to mean high level symbols Directly correspond to objects in the world, such as “monkey” and “table”. …but the weights and connections in a neural network could also be represented as symbols Use this to make a “scruffy” representation of “monkey” but that’s not considered to be what they meant

“A physical symbol system has the necessary and sufficient means of general intelligent action.” Most AI people nowadays would not accept the idea of high level symbols being sufficient Seems to work well for playing chess, problem solving (if problem well defined) but doesn’t work so well for some “easy” problems Vision, moving around in the world *** But most AI people would accept the computational theory of mind (i.e. Functionalism)

Universal Computing Machine
Turing machine: Actions: Head can move left and right over the tape Can read and write symbols on the tape Can overwrite symbols on tape Machine has an internal state Takes Action depending on state Turing’s thesis: “If an algorithm exists then there is an equivalent Turing Machine” Turing machine is the simplest possible description of a computer that can do anything All modern computers can be simulated by a Turing machine Only real difference: Turing machine has infinite tape, real computers have finite memory

How many symbols and states do you need?

How many symbols and states do you need? Interesting… If you make some really fancy machine… Loads of states Loads of possible symbols Multiple tapes Multiple stacks for storing things Many heads working in parallel You end up with something equivalent to the Turing machine States Symbols 24 2 10 3 7 4 5 6 18

The Turing machine has a set of rules These determine how it acts Can make a Universal Turing machine Encode the rules you want it to use on the tape The first thing it does is to read the rules Then follow them… Could also reprogram its rules as it goes along Important ability for learning Behaviour must change given experience

We said “If an algorithm exists then there is an equivalent Turing Machine” i.e. a (different) Turing machine is available to do any job we want to do Now we can say “If an algorithm exists then it can be simulated on a Universal Turing Machine” i.e. all we need is a single Universal Turing Machine This can do anything This is the idea behind modern computers Program instructions stored in memory just like any other data Download a program off the web, and start running it You don’t need a different computer for different jobs One computer can do everything Games, spreadsheet, database, music, movies, photo editor, word processor…

Is the Brain a Universal Computing Machine?
Warren McCullogh and Walter Pitts showed Small collections of neurons can act as “logic gates” (building blocks of computers) Brain could be viewed as a computing device, just like Turing machine i.e. a brain can do what a computer can do Other direction is a stronger claim Can a computer do what a brain can do? Can’t be proved But universality of Turing machine suggests… maybe

Clarifying what Functionalism is…
Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … Motor output sensoryinput Physical Implementation

Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … Functionalism says we can study the information processing tasks (and algorithms for doing them) independently from the physical level Motor output sensoryinput Physical Implementation

This means they are “multiply realisable” = able to be manifested in various systems, even perhaps computers, so long as the system performs the appropriate functions (Wikipedia definition) Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … Functionalism says we can study the information processing tasks (and algorithms for doing them) independently from the physical level Motor output sensoryinput Physical Implementation

Central systems Motor systems Sensory systems What about Brooks? (remember tutorial article) Is he a functionalist? Yes! Otherwise he wouldn’t be trying to use computers to implement the processing in his robots. He would instead be trying to use some organic system, as a non-functionalist would believe that the processing happening in an animals’ neurons could not be performed by a computer Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … Motor output sensoryinput Physical Implementation

So what was it Brooks was saying about the “real world”? Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … Motor output sensoryinput Physical Implementation

So what was it Brooks was saying about the real world? Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … He said this side needs to be connected to the real world, not a simulation e.g. digital camera getting data from real world, with noise, and messy lighting conditions, etc. Motor output sensoryinput Physical Implementation

So what was it Brooks was saying about the real world? Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … He said this side needs to be connected to the real world, not a simulation e.g. wheels on the robot, which might slip on the ground or stick on the carpet, etc. i.e. messy Motor output sensoryinput Physical Implementation

So what was it Brooks was saying about the real world? Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … He didn’t say he had any problem with the algorithms being implemented on a computer Motor output sensoryinput Physical Implementation

Central systems Motor systems Sensory systems Sight Hearing Taste Smell Touch Balance Heat/cold … Categorisation Attention Memory Knowledge representation Numerical cognition Thinking Learning Language Voice Limbs Fingers Head … Motor output sensoryinput Continuing question from last lecture: How does this central system work? Physical Symbol System

The Physical Symbol System
Some sort of Physical Symbol System seems to be needed to explain human abilities Humans are “programmable” We can take on new information and instructions We can learn to follow new procedures e.g. a new mathematical procedure Human mind is very flexible …But not true of other animals, even apes Animals have special solutions for specific tasks Frog prey location Human flexible Physical Symbol System must have evolved from animals’ processing systems Details of physical implementation are unknown Let’s stick with Physical Symbol System for now… See can we flesh out more details

The Language of Thought
What is the language we “think in”? Is it our natural language, e.g. English, or mentalese? Some introspective arguments against natural language Word is “on the tip of my tongue”, but can’t find it Difficult to define concepts in natural language, e.g. dog, anger We have a feeling of knowing something, but hard to translate to language Some observable evidence against natural language Children reason with concepts before they can speak We often remember gist of what is said, not exact words Cognitive science experiment: (recall after 20 second delay) He sent a letter about it to Galileo, the great Italian Scientist. He sent Galileo, the great Italian Scientist, a letter about it. A letter about it was sent to Galileo, the great Italian Scientist. Galileo, the great Italian Scientist, sent him a letter about it.

Course Overview What is AI? What are the Major Challenges?

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