The Newell Test for a Theory of Mind

1. The Newell Test for a Theory of Mind • Anderson, John R., & Lebiere, Christian (forthcoming), “The Newell Test for a Theory of Mind”, Behavioral & Brain Sciences • Newell, Allen (1980), “Physical Symbol Systems”, Cognitive Science 4: 135-183. • Newell, Allen (1990), Unified Theories of Cognition (Cambridge, MA: Harvard University Press).

2. The Newell Test • Based on lists of criteria that cognitive theories should satisfy. • Anderson & Lebiere: • Classical connectionism: • Newell-test strengths: • Addresses empirical phenomena • Especially in language, cognitive development • NT weaknesses: • Fails to acknowledge symbolic level of thought • ACT-R (Anderson’s own theory): • NT strengths: • Includes symbolic & subsymbolic components • Both are tightly integrated • NT weaknesses: • Lacks intensive analyses of some NT criteria

3. Newell’s Criteria: Summary • 12 functional constraints on cognitive architecture • First 9: • Things needed “to implement human intellectual capacity” • Last 3: • “Constraints on how these functions are to be achieved” • There are others, not on the list: • E.g., a system could satisfy all 12, but “not correspond to the human mind” • So: could add others (but won’t): • Behavioral adequacy: • cognitive theory should correspond to details of human cognition • Be capable of practical application (e.g., to education, therapy) • There is a grading scheme!

4. Newell’s 12 Criteria • Flexible behavior • Real-time performance • Adaptive behavior • Vast KB necessary • Dynamic behavior for • Knowledge integration cognition • Natural language • Consciousness • Learning • Development • Evolution constraints • Brain

5. 1. Flexible Behavior • I.e., computational universality • Grading: • If theory is well-specified, then s/b easy to determine whether computationally universal • Doesn’t require that: • people find everything equally easy • human performance be error free

6. 2. Real-Time Performance • Theory should explain how humans can satisfy criterion 1 in real time • Grading: • If theory has well-specified constraints on speed of its processes, then s/b easy to determine whether it can achieve real time for specific cases of cognition

7. 3. Adaptive Behavior • Human computations are relevant to their needs • How do basic processes of the architecture serve useful functions? • How is the whole system put together? • Does its overall computation meet human needs? • Grading: • If theory is completely specified, then s/b able to determine if its behavior would be functional in real world

8. 4. Vast Knowledge Base • Distinguishes human cognition from expert systems • Problems: • Not all K is equally reliable or relevant • Relevance can change with time • Storage/retrieval problems • Grading: • Determine how performance changes with scale of KB • If theory is well specified, then s/b able to formally analyze • Size may affect performance • Cf. learning names of 20 students vs. 200 students

9. 5. Dynamic Behavior • Precondition for survival: • World can change in unexpected & uncontrollable ways • Human actions can have unexpected effects • Requires theories of perception, action, & cognition • BUT: NOT(reaction is all there is to cognition) • But also: NOT(cognition can ignore external world) • Grading: • Test system in an uncontrolled environment

10. 6. Knowledge Integration • I.e., achieving the capability to “combine symbols intellectually” in order to make inferences about the external world • Grading: • Can the theory deal with inference, induction, metaphor, analogy

11. 7. Natural Language • Complete theory of mind must be able to communicate in NL • Newell: language depends on symbol manipulation (! ) • Grading: • Read a passage & answer questions about it. • Requires parsing, comprehension, inference, use of prior knowledge • Conversational ability is nice, but not necessary

12. 8. Consciousness • Important for a full theory of human cognition • [what about a full theory of cognition, simpliciter?] • Grading: • Ability to produce subliminal perception, implicit learning & memory, metacognitive processes • & show how they are functional aspects of human cognition

13. 9. Learning • “Theory of cognition must account for humans’ ability to acquire their competencies” • Grading: • Semantic memory, episodic memory, skills, priming, conditioning • Based on Squire’s (1992) theory of memory in the hippocampus

14. Development (constraint #1) • Human cognition is constrained to unfold as the organism grows & responds to experience. • Grading: • Can the theory account for specific cases of developmental progression?

15. 11. Evolution (constraint #2) • Evolutionary constraint: • Human cognitive abilities evolved • Comparative constraint: • Differences between human and other-mammalian cognition • E.g., cognitive plasticity, language • What’s unique to human cognition? • Grading: • How does the theory relate to these constraints?

16. 12. Brain (constraint #3) • Degree to which data about brain functioning constrains the cognitive theory. • Grading: • Enumeration: • Mapping of parts of the cognitive architecture onto brain structures • Proof: • Brain computations match cog-arch computations

17. Grading • BEST: criterion on which theory has done the best • Better: 4 criteria on which the theory has done better • mixed: 2 criteria on which theory has most mixed record • worse: 4 criteria on which the theory has done worse • worst: criterion on which theory has done the worst

18. Scoreboard

19. Comparative Ranking