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ACT-R Workshop John R. Anderson Daniel Bothell Christian Lebiere Niels A. Taatgen

ACT-R Workshop John R. Anderson Daniel Bothell Christian Lebiere Niels A. Taatgen. Schedule of Events: 9:00-10:30: ACT-R from CMU’s Perspective 11:00-12:30: Architecture 1:30-3:30: Extensions 4:00-5:30: Future of ACT-R from a non-CMU Perspective

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ACT-R Workshop John R. Anderson Daniel Bothell Christian Lebiere Niels A. Taatgen

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  1. ACT-R WorkshopJohn R. AndersonDaniel BothellChristian LebiereNiels A. Taatgen Schedule of Events: 9:00-10:30: ACT-R from CMU’s Perspective 11:00-12:30: Architecture 1:30-3:30: Extensions 4:00-5:30: Future of ACT-R from a non-CMU Perspective And lots of Interaction!

  2. ACT-R Workshop Schedule • Opening: ACT-R from CMU’s Perspective • 9:00 - 9:45 Overview of ACT-R -- John R. Anderson • 9:45 – 10:30 Details of ACT-R 6.0 -- Dan Bothell • Break: 10:30 – 11:00 • Presentations 1: Architecture • 11:00 – 11:30 Functional constraints on architectural mechanisms -- Christian Lebiere • 11:30 – 12:00 Retrieval by Accumulating Evidence in ACT-R -- Leendert van Maanen • 12:00 – 12:30 A mechanism for decisions in the absence of prior reward -- Vladislav D. Veksler • Lunch: 12:30 – 1:30 • Presentations 2: Extensions • 1:30 – 2:00 ACT-R forays into the semantic web -- Lael J. Schooler • 2:00 – 2:30 Making Models Tired: A Module for Fatigue -- Glenn F. Gunzelmann • 2:30 – 3:00 Acting outside the box: Truly embodied ACT-R -- Anthony Harrison • 3:00 - 3:30 Interfacing ACT-R with different types of environments and with different techniques: Issues and Suggestions.-- Michael J. Schoelles • Break: 3:30 – 4:00 • Panel: 4:00 – 5:30: Future of ACT-R from a non-CMU Perspective • Danilo Fum, Kevin A. Gluck, Wayne D. Gray, Niels A. Taatgen, J. Gregory Trafton, Richard M. Young

  3. Overview of ACT-RJohn R. AndersonCarnegie Mellon University Outline: • 9:10: Big picture of what ACT-R is about • 9:20: Evolution of the Procedural Module • 9:30: Evolution of the Declarative Module • 9:35: How ACT-R spreads

  4. ACT-R is Not Monolithic It is a community brought together by common theoretical assumptions and a commitment to the “No Magic” Principle -- cognitive theory has to run and it has to predict data. While ACT-R may be sustained from CMU it no longer resides at CMU. The community motto is “Let a thousand flowers grow” It is a set of software for purposes of simulation. This software consists of a core LISP implementation, but there are many theoretically-motivated extensions and alternative practicality-motivated alternative implementations. In some cases the software provides the best definitions of what the theoretical claims are. It is a theory that attempts to formalize and operationalize certain aspects of our understanding of the human mind. This includes assumptions that are more core and those that are more peripheral. It changes as our knowledge grows and has different interpretations in different hands.

  5. ACT-R: The Oldest Core Principles • 1. The Procedural-Declarative Distinction • a. The declarative component originated in Anderson & Bower (1973) HAM network representation of memory. • b. The procedural component originated in Newell’s (1973) production system theory of cognitive control. • c. Both the procedural and declarative components have evolved far from these origins. • The Symbolic-Subsymbolic Distinction • In addition to the symbolic level that represented knowledge there is a subsymbolic level that controls access to that knowledge. • The subsymbolic level was initially designed to reflect the 1970s & 1980s ideas about neural processing. • Guided by rational analysis the subsymbolic level was updated in 1993 to reflected the likelihood that the information was useful. This was the birth of ACT-R.

  6. Evolution from ACT-R 2.0 (1993) to ACT-R 6.0 (2007) • 1. There were 3 driving forces: • a. The emergence of a user community around the publicly available ACT-R 2.0. • b. The realization that the “No Magic” principle required that we be able to model the processing all the way from input to output. • c. The insistence on not making assumptions that could not be cashed out into neurally plausible computations. • This converged in the modular architecture of ACT-R 6.0: • The allowed community members to try variations on existing ideas and extensions but keep what they wanted. • We borrowed the modular organization of EPIC for the perceptual-motor modules. • There was growing evidence that, while the brain was a complex parallel machine, different regions had their specializations.

  7. Goal Imaginal Declarative Procedural Buffers provide narrow paths of communication -- only hold a chunk in ACT-R terms. Aural Visual Production system that contains rules that recognize patterns and react Vocal Manual Modules in ACT-R 6.0 Modules are high capacity, parallel, and asynchronous

  8. ACT-R Module-Region Mappings

  9. Outline: • 9:10: Big picture of what ACT-R is about • 9:20: Evolution of the Procedural Module • 9:30: Evolution of the Declarative Module • 9:35: How ACT-R spreads

  10. The Procedural Component in ACT-R has Evolved from Computer Science Notation to Description of the Brain’s Action Selection • 600517 • 23523 • 4

  11. Goal> Task: Subtracting Request Difference Goal> Task: Process-Column Imaginal> Top: 7 Relation: >= Bottom: 3 Declarative> Type: subtraction Minuend: 7 Subtrahend: 3 If the goal is to process a column and the top digit is not smaller than the bottom digit, Then write the difference between the digits as the answer The First Real ACT-R Production Rule Selects an Action Responds to a Particular Pattern that Appears in the Buffers of a Set of Modules Which consists of requests to other Modules

  12. Harvest Difference If the goal is to process a column and the top digit is not smaller than the bottom digit, Then write the difference between the digits as the answer The Second Real ACT-R Production Rule Responds to a Particular Pattern that Appears in the the Buffers of a Set of Modules Selects an Action Which consists of requests to other Modules Goal> Task: Subtracting Goal> Task: Next-column Declarative> Type: subtraction Difference: 4 Manual> Action: write Digit: 4

  13. Attributes of Production Rules • Production rules are stimulus-response bonds that have “gone over to the cognitive side” because among the stimuli they respond to are past memories, mental images, and control states. • Respond to conjunctions of elements in the various buffers. • These buffers can represent relational structures -- e.g. A above B. • Note how innocuous the use of variables is -- it basically copying information from one brain region to another. • Stewart, T.C. and Eliasmith, C. (2008). Building production systems with realistic spiking neurons. 30th Annual Meeting of the Cognitive Science Society. • Stocco, A., Lebiere, C., & Anderson, J. R. (in revision). Conditional routing of information to the cortex: A model of the role of basal ganglia in high-level cognition. Psychological Review

  14. Requires Deliberation Declarative Representations Interpreted Analogy to Prior Experiences (e.g. Past Tense Model) Following instructions (e.g. Multicolumn Subtraction) Deduction From 1st Principles Traces Feed Into Production Compilation Eventually Produces New Production Rules Learning of New Production Rules New Problem Situations

  15. Origin of One of the Subtraction Rules Production compilation compresses general-purpose processing of knowledge into special case rules -- replacing deliberation by action.

  16. Retrieve-Instruction (Reinforcement 10) If the goal is to process a column Then retrieve an operator for that kind of column Reinforcement of Competing Productions Request-Difference-Subtract (Reinforcement 14) If the goal is to process a column and the top digit is not smaller than the bottom digit, Then subtract the bottom from the top Request-Difference-Borrow (Reinforcement 14) If the goal is to process a column and the top digit smaller than the bottom digit, Then add 10 to the top digit and set as a subgoal to borrow from the column to the left. Request-Difference-Wrong (Reinforcement 14 or 0) If the goal is to process a column Then subtract the smaller from the larger

  17. Every time a rule created it is rewarded with the utility of its parent Considerable simplification of ACT-R utility learning based of reinforcement-like learning results from the basal ganglia Standard ACT-R soft-max rule for choosing among productions according to their noisy utilities Utility Learning for Competing Productions

  18. Outline: • 9:10: Big picture of what ACT-R is about • 9:20: Evolution of the Procedural Module • 9:30: Evolution of the Declarative Module • 9:35: How ACT-R spreads

  19. What has Happened to the Declarative Component in ACT-R? • It has bifurcated into two completely separate things: • An increasingly watered-down set of principles for the representation of knowledge, which comes to be the contents of module buffers. This is clearly a place where important new thinking is required. • An increasingly empirically well-founded set of principles (with a foundation in rational analysis) for how the brain performs controlled retrieval of information from declarative memory.

  20. Goal Imaginal Declarative Procedural Aural Visual Vocal Manual • Buffers associated with modules provide narrow paths of communication. • The contents of the buffers are called chunks. • Records of these chunks are placed in declarative memory. • These can be later retrieved and placed in the declarative buffer. Buffers and Declarative Memory

  21. Environmental Equation: Posterior odds that memory i will be needed in context C Prior odds that i is needed: recency and frequency Likelihood ratio of element j in context given i is needed Weighting of Source j Momentary Activation of memory i Activation Equation: Base-level Activation of memory i Association Strength from j to i Chunk Activation Reflects Probability of Use

  22. Fan Experiment: Pirolli & Anderson (1985)

  23. Activation Level Growth of Activation

  24. intercept latency scale Recognition Time (ms.) Recognition Latencies r = .986 is a parameter-free measure of the match between theory and data.

  25. Outline: • 9:10: Big picture of what ACT-R is about • 9:20: Evolution of the Procedural Module • 9:30: Evolution of the Declarative Module • 9:35: How ACT-R spreads

  26. Declarative Module Goal Buffer Retrieval Buffer Matching Problem Buffer Productions Selection Pacemaker Gate Accumulator Pacemaker Gate Accumulator Execution Memory StartSignal StartSignal Visual Buffer Manual Buffer Comparison Visual Module Manual Module External World Temporal Module: An Example of How One Can Extend ACT-R

  27. Other Module Extensions for ACT-R • Salvucci’s Emma Module for Eye Movements. • My new Metacognitive Module. • Spatial Modules (Gunzelmann, Harrison & Trafton). • Fatigue Module (Gunzelmann) ???? • Reasoning Module LarKC (Schooler)????

  28. Module Modifications • SNIF-ACT (Fu & Pirolli): Procedural and Declarative. • Threaded Cognition (Salvucci & Taatgen): Goal • Spacing Effect (Pavlik): Declarative. • Blending (Lebiere): Declarative. • Race/A (van Maanen & Van Rijn): Declarative • Visual Saliency (Byrne): Visual. • Gray, Veksler, & and others of the RPI Co: Procedural. • Bothell & Leabra: Visual.

  29. You Don’t Need to Change ACT-R to Have an Interesting Model • Fum & Stocco: Sugar Factory • Lebiere, Wallach, & Taatgen: Sugar Factory • Altmann & Trafton: Tower of Hanoi • Lewis & Vasishith: Parsing • Taatgen: Acquistion Past Tense Model • Anderson (2007) & Everybody (recently): Everything in fMRI • And indeed most of the published ACT-R models.

  30. Getting ACT-R out of the Narrow Confines of Laboratory Experiments • Best & Lebiere: MOUT • St. Amant & Ritter: Segman • Bothell, Douglass, Lee: Unreal Tournament • Harrison & Trafton: Robotics • Destefano: Space Fortress • Schoelles: Lots of Interfaces

  31. ACT-R is Not Monolithic It is a community brought together by common theoretical assumptions and a commitment to the “No Magic” Principle -- cognitive theory has to run and it has to predict data. While ACT-R may be sustained from CMU it no longer resides at CMU. The community motto is “Let a thousand flowers grow” It is a set of software for purposes of simulation. This software consists of a core LISP implementation, but there are many theoretically-motivated extensions and alternative practicality-motivated alternative implementations. In some cases the software provides the best definitions of what the theoretical claims are. It is a theory that attempts to formalize and operationalize certain aspects of our understanding of the human mind. This includes assumptions that are more core and those that are more peripheral. It changes as our knowledge grows and has different interpretations in different hands.

  32. 2007 (p. 12 Architecture of Cognition, 1983) Be Fruitful and Multiply!

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