metacognition in computation: a selected history michael t. cox bbnt cambridge
TRANSCRIPT
Metacognition in Computation: A selected history
Michael T. CoxBBNT Cambridge
22 March 2005 2
Why Metacognition?
“What then can be the purport of the injunction, know thyself? I suppose it is that the mind should reflect upon itself.”
-- Augustine, De Trinitate, 16th century
22 March 2005 3
Why Metacognition?
• Separates us from the rest of the species
• Separates smarter people from less smart
• Provides a heuristic basis for decisions– E.g., I am good at home repair, so I can risk
embarrassment by volunteering to fix the broken pipe rather than calling a plumber.
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Metacognition is Ubiquitous
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Why NOT Metacognition?
• Complexity – space and time
• Actual human limitations– Easier to show when metacognition does not
work rather than how it does
• AI hype
22 March 2005 6
AI Hype
“Once self-description is a reality, the next logical step is self-modification. Small, self-modifying, automatic programming systems have existed for a decade; some large programs that modify themselves in very small ways also exist; and the first large fully self-describing and self-modifying programs are being built just now. The capability of machines have finally exceeded human cognitive capabilities in this dimension; it is now worth supplying and using meta-knowledge in large expert systems.”
-- Lenat, Davis, Doyle, Genesereth, Goldstein, and Schrobe 1983 (p. 238)
22 March 2005 7
What is Metacognition?
• Meta-X is defined as “X about X”• Metacognition is cognition about
cognition• Metareasoning is reasoning about
reasoning• Metaknowledge is knowledge about
knowledge• Metamemory, metarepresentation,
metacomprehension, metalogic, metaplans,meta...
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But what about…
• Meta-levels
• Reflection
• Introspection
• Self-awareness
• Self-explanation
• Consciousness?
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Outline of Presentation
• Psychology, Metacognition, and Human Behavior
– Cognition and Metacognition
– Problem Solving and Metacognition
– Metamemory
• Artificial Intelligence, Metareasoning, and Introspection
– Logic and Belief Introspection
– Knowledge-Based Systems, Metareasoning, and Control
– Model-Based Reasoning, Case-Based Reasoning and Introspective Learning
22 March 2005 10
What is Not Being Covered?
• Social Psychology
• Philosophy
• Cognitive Neuroscience
• Consciousness Studies
• Theological Accounts
22 March 2005 11
Psychology, Metacognition, & Human Behavior
• Earliest Research – circa 1900– Brown, A. 1987. Metacognition, Executive Control, Self-
regulation, and Other More Mysterious Mechanisms. In F. E. Weinert and R. H. Kluwe eds. Metacognition, Motivation, and Understanding 65-116. Hillsdale, NJ: LEA.
• Text comprehension and metacognitive activities studied, but under different names.
• Not to be confused with introspectionism
22 March 2005 12
Cognition & Metacognition
• Earliest Research – John Flavell– Flavell, J. H. 1971. First Discussant’s Comments: What Is
Memory Development the Development of? Human Development 14: 272-278.
– Flavell, J. H. 1976. Metacognitive Aspects of Problem Solving. In Resnick ed. The Nature of Intelligence, 231-235. Hillsdale, NJ: LEA.
• Much of the work has been in the child development and cognitive aging research communities
22 March 2005 13
Wellman’s Theory
• Wellman, H. M. 1992. The Child's Theory of Mind. Cambridge, MA: MIT Press.
• Children come to construct a naive theory of mind by observing the difference between self and others– Before age of three – no distinctions – At age of three – difference between wants and
actions; between ideas and reality– After age of three – mind as processor and interpreter
22 March 2005 14
Metacognitive Variables
• Person Variables– Deals with the individual and others– Cognitive psychologists can recall many facts about
cognition
• Task Variables– Concerns the type of mental activity– Harder to remember nonsense words
• Strategy Variables– Alternatives to mental tasks– To remember a list it helps to rehearse
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Theory-Theories
• Theories have – Coherence– Ontology– Causal-explanatory structure
• Theories of Mind– Mental constructs self-refer– Distinctions between things and ideas– Desires and beliefs effect thought and action
22 March 2005 16
Children’s Theory of Mind
• Different than adults
• More than just a collection of facts about mental phenomena
• Experiment for 3-yr-olds– Sally sees candy put in a bag– Sally leaves room– Candy placed in a drawer– Sally returns, where will she look for candy?
22 March 2005 17
Problem Solving & Metacognition
• Earliest Research – Dörner– Dörner, D. 1979. Self-Reflection and Problem-solving. In F. Klix
ed. Human and Artificial Intelligence, 101-107. Amsterdam: North Holland.
• Subjects that introspect versus those that do not with all else the same
• Surprisingly very little work altogether
22 March 2005 18
Derry’s Theory
• Comprehensive model of reflective problem-solving for mathematical word problems
• Inspired by ACT* (Anderson)• Four basic phases
1. Clarifying a problem2. Developing a strategy3. Executing a strategy4. Monitoring/Checking
22 March 2005 19
Derry’s Experiment
• Computer-based instructional system
• Teaches math word problems to military personnel and college students
• Assumption: Goal backchaining and MEA form bases for human problem-solving
• Gather subject protocols during testing
• Categorize protocols and correlate with performance
22 March 2005 20
Derry’s Results
• Neither group had linear performance• Protocols fell into clarification and execution• Considered checking math answers as
metacognitive
Group Clarify Plan Execute Check Other
Army (n=8)
44 7 36 3 10
College (n=8)
41 2 49 3 5
22 March 2005 21
Swanson’s Research
• Separate cognitive abilities from metacognitive abilities
• Standardized test scores and meta-cognition questionnaires (Hultch, Hertzog, Dixon, & Davidson 1988)
• Measure problem-solving performance
• High/Low aptitude interacts with high/low metacognition
22 March 2005 22
Metamemory
• Earliest Research – John Flavell– Flavell, J. H., and Wellman, H. M. 1977. Metamemory. In R. V.
Kail, Jr., and J. W. Hagen eds. Perspectives on the Development of Memory and Cognition, 3-33. Hillsdale, NJ: LEA.
• Knowledge of and memory for memory
22 March 2005 23
Knowing without Remembering
22 March 2005 24
Kausler and Lovelace’s Theory
Kausler– Off-line memory evaluation– On-line memory evaluation
Lovelace• Pre-performance estimates (predictions)• On-line memory monitoring
– FOKs – Postdictions– Reality monitoring– JOLs
– Memory performance monitoring
22 March 2005 25
Information Processing Models
• T. Nelson and Narens – Information processing view– Monitoring component and control component
• M. T. H. Chi and K. VanLehn – The self-explanation effect
• P. Pirolli and M. Recker– Soar model + GRAPES– Subjects that explained between experiments
tended to learn better
22 March 2005 26
Reder’s Theory
• Game show paradigm• Two stages of memory
retrieval exist– Fast familiarity judgment– Slower search stage
• Conclusion– Correlated with question
terms not answers
22 March 2005 27
SAC Model
• Source of Activation Confusion
• Spreading activation model
• Base-line strength change as the power function
• Activation change due to neighbors is
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22 March 2005 28
AI, Metareasoning & Introspection
• Earliest Research – Minsky and McCarthy– Minsky, M. L. 1965. Matter, Mind, and Models. In Proceedings of
the International Federation of Information Processing Congress 1965 (Vol. 1) 45-49.
– McCarthy, J. 1959. Programs with Common Sense. In Symposium Proceedings on Mechanisation of Thought Processes (Vol. 1), 77-84. London: Her Majesty’s Stationary Office.
• Models of Models
• Declarative Knowledge for the Self
22 March 2005 29
Minsky’s Theory
• Minsky, M. L. 1965. Matter, Mind, and Models. In Proceedings of the International Federation of Information Processing Congress 1965 (Vol. 1) 45-49.
• To answer questions about the world and the self in the world, an agent must have a model it can query
• W, M, W*, M*, W**, M**
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22 March 2005 31
McCarthy’s Theory
• McCarthy, J. 1959. Programs with Common Sense. In Symposium Proceedings on Mechanisation of Thought Processes (Vol. 1), 77-84. London: Her Majesty’s Stationary Office.
• Knowledge as logic
• Logic as thinking
• What does it mean for a robot to be conscious?
22 March 2005 32
Logic & Belief Introspection
• Self-Reference and “aboutness” (Perlis)– Liar’s Paradox from time of Socrates– This sentence is false.
• FOL axiomization and possible worlds (Moore)
• Belief is different than facts (Hintakka)
• Model-Theoretic reasoning
• Metalogics and proving provability
22 March 2005 33
Konolige’s Deduction Model
• Alternative to Possible Worlds Semantics
• Deduction Structure is a mathematical abstraction of bounded belief systems
• Machines and introspective machines
• Intrinsic and extrinsic self-beliefs
• Separation of IM from M resolves some problems of self-reference
22 March 2005 34
Logical Representations
• Is-Complex-wrt
(John,
)
• How to handle?
))"(,()(." pAboutpKnowspPersonp
22 March 2005 35
Knowledge-Based Systems, Metareasoning & Control
• Earliest Research – Metaknowledge in expert systems– Barr, A. 1977. Meta-Knowledge and Memory, Technical Report,
HPP-77-37. Stanford University, Department of Computer Science, Stanford, CA.
– Davis, R. 1976. Applications of Meta-Level Knowledge to the Construction, Maintenance, and Use of Large Knowledge Bases. Stanford HPP Memo 76-7. Stanford University.
• Metarules: the red herring of AI
22 March 2005 36
Davis’ Theory
• Knowledge engineering in MYCIN
• Metaknowledge 1. Schemas2. Function templates3. Metarules4. Rule models
• Rule models help interpret what expert asserts
Performance ProgramDomain
Expert
TEIRESIAS
knowledge transfer
explanation Inference Engine
Knowledge Base
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Example Rule Model
INVESTMENT-AREA-IS1. Examples ((rule116 0.3) (rule050 0.7)
(rule037 0.8) (rule095 0.9) (rule152 1.0))2. Description
– Premise ((returnrate same notsame 3.8) (timescale same notsame 3.8) (trend same) ((returnrate same)(timescale same) 3.8) …
– Action ((investment-area conclude 4.7) (risk conclude 4.8))…
3. More-general (investment-area)4. More-specific (investment-area-is-utilities)
22 March 2005 38
Model-based Understanding & Learning by Experience
Knowledge Base
Rule Models
Rule Acquisition(knowledge acquisition)
Expert
(dialog)
(model-directed understanding)
(concept formation)
22 March 2005 39
Problems with Expert Systems
• Confuses abstraction with metacognition
• Confuses control with metacognition
• Self-understanding software tangent?
• Explanation is not a rule chain or proof tree
• Knows what it does not know?
22 March 2005 40
Metareasoning
• Earliest Research – Bounded rationality– Simon, H. A. 1955. A Behavioral Model of Rational Choice.
Quarterly Journal of Economics 69: 99-118.
• Earliest Research – Good’s Type II rationality– Good, I. J. 1971. Twenty-Seven Principles of Rationality. In V. P.
Godambe and D. A. Sprott eds. Foundations of Statistical Inference. Toronto: Hold, Rinehart, Winston.
22 March 2005 41
Wesfald’s Theory
• Treating computation selection as action selection by maximizing expected utility– Cost of time (world changes by itself)– Benefit of better action choices
– Execution cost– Resource cost
22 March 2005 42
System Unification
Unifies decision-making systems
• Decision-theoretic systems
• Production systems• Goal-based systems• Reactive systems• EBL systems
Unifies meta-cognitive systems
• MRS (Genesereth)• TEIRESIAS (Davis)• Soar (Newell)
22 March 2005 43
Decision Stages and Shortcuts
Condition (s)
Condition (result(a,s))
Utility (result(a,s), v)
Best (a,s)
A
B
EF
C
DTD
22 March 2005 44
Model-based Reasoning & CBR
• Earliest Research – Schank’s emphasis on memory and representation– Schank, R. C., Goldman, N., Rieger, C., and Riesbeck, C. K.
1972. Primitive Concepts Underlying Verbs of Thought (Stanford Artificial Intelligence Project Memo No. 162. Stanford, CA: Stanford University, Computer Science Department. (NTIS No. AD744634)
• Using Conceptual Dependency primitives to represent remember, forget, think, expect…
22 March 2005 45
Case-Based Explanation
• Provides a framework for interpreting Failures– In world actions– In reasoning actions (e.g., memory retrieval)– In social actions
• Example: Dog barking story– S1 Police & Dog enter airport baggage area– S2 Dog sniffs luggage.– S3 Dog Barks at luggage.– S4 Police arrests suspect.
22 March 2005 46
Computational Introspection
• To reason about the self…
• When reasoning about the world fails use meta-reasoning to explain the failure
• Map from symptom of the failureto the cause of the failure
• Learn
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Symptoms of Failure
Actual eventdoes not exist
FalseExpectation
Impasse
Surprise
Contradiction
Unexpected Success
Actual event exists
Expectation does not exist
Expectationexists
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Causes of Failure
Missing
Incorrect
Correct
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Stranded Motorist Example• Planning a vacation
– Destination– Reservation– Supplies– Gas
• Plan Execution– Goes to store– Buys supplies– Drives to mountains– Runs out of gas
• Failure Recovery– Get gas can– Walk to gas station or hitch-hike– Fill can with gas– Return to Fill tank– Continue
• Failure Repair– Regress goals to features in initial state– Use features as index to store as new case
• Alternate Repair– Reason about the reasoning that led to the failure– Cause was forgetting to fill car with gas at store– Form association between going on long trip and
checking gas gauge
Causal Possibilities Tree
• Sub-goals– Be at store– Make purchases
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Forgetting to Fill-Up with Gas
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Problems with Metacognition
• Control and rules– Abstract rules are not really different from
concrete rules
• Metaknowledge– Knowledge about facts is not really different
from ordinary facts
• Many synonymous and overloaded terms
• Overstating Benefits
22 March 2005 52
Conclusion
• The “Many-headed Monster of obscure parentage” –Brown (1987)
• Lessons to be learned
• Failures to be avoided
• Current research has the potential to be qualitatively different because of the technical maturities and funding commitments
22 March 2005 53
A Grain of Salt
“To know oneself is only half as good as knowing two selves.”
--Homer
(Simpson)