1. Abstraction and ACT-R

2. Outline Motivations for the Theory –Architecture –Abstraction Production Rules ACT-R Architecture of Cognition

3. Architecture There is a distinction between brain architecture and cognitive architecture. This is a difference between the physical description of the system, and the functional properties that it enables. Some examples…

9. The common feature to each is in the method of abstraction. –Moving from a more complex, lower level system of interaction, to a higher level language in which those lower level features are typed. Some Characteristic features of Abstraction.

10. Constraints on the Abstraction Typing –Lower level features are given higher level types Simplification –The higher level abstraction is obligated to simplify conceptual complexity Morphism –There must be a mapping. –‘Many to one’

11. Production Systems Comprise a language with sentences of the form If > then > Developed by Emil Post (1943), also known as ‘Post Production Rules’ Turing Complete

12. Solve a Linear Equation If the expression has X = N, where N is a number, THEN halt and check by substituting N in the original equation If there is a term in X on the right-hand side, THEN subtract it from both sides, and collect the terms. IF there is a numerical term on the left hand side, THEN subtract it from both sides, and collect the terms IF the equation has the form NX = M, N = 1, THEN divide both sides by N

13. If the expression has X = N, where N is a number, THEN halt and check by substituting N in the original equation If there is a term in X on the right-hand side, THEN subtract it from both sides, and collect the terms. IF there is a numerical term on the left hand side, THEN subtract it from both sides, and collect the terms IF the equation has the form NX = M, N = 1, THEN divide both sides by N X = 2X + 5 X – 2X = 2X – 2X + 5 -X = 5 X = -5

14. ACT-R (Adaptive Control of Thought-Rational) Modules Buffers Productions

15. Modules - Fodor (Modularity of Mind) Features –Functional separation Domain specific Interaction between modules

16. Buffers Active Content Interface Interaction between modules –Provides the link

17. Productions If > then > State Change –Contents of Buffer –Contents of Modules

18. Learning Adaptive control –Update Goal structures Declarative memory contents Productions

19. Structure of Declarative Module ‘Chunks’ – A collection of related information. Action023: isa chase agent dog object cat Fact3+4: isa addition-fact addend1 three addend2 four sum seven

20. Summary Cognitive Science and Act-R benefit by engaging in abstraction By matches conditions set by contents in the buffer, and specifying to changes in that content. Act-R models cognition.