1 lecture_sept8

1 lecture_sept8 - ACT-R overview How does structure achieve...

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Copyright Thomas R. Shultz 1 ACT-R A production-system cognitive architecture ACT-R 2 ACT-R overview • How does structure achieve function? • A unified theory of cognition realized as a production system • Designed to predict human behavior by processing information & generating intelligent behavior • Integrates cognition, visual attention, & motor movement • Models many cognitive phenomena such as working memory, scientific reasoning, skill ACT-R 3 Types of knowledge •Dec la ra t i ve – Conscious awareness – Can describe to others –Facts Ottawa is the capital of Canada 5 x 7 = 35 • Procedural – Display in behavior – Unconscious – E.g., language, inference, action ACT-R 4 Chunks of declarative knowledge • Type - category (bird) • Slots - attributes (color, size) ACT-R 5 Production for adding digits in column • If • Then – set as a subgoal to write d3 in the column ACT-R 6 Productions in general • Conditions – May depend on declarative knowledge (i.e., recall of a chunk) – Specification of goal & number of chunks
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2 ACT-R 7 Production for counting • If – goal is to count – & a count-order with num1 & num2 is retrieved • Then – change the goal to count from num2 ACT-R 8 Detailed production for counting ACT-R 9 Architecture of ACT-R 6 ACT-R 10 Modules • Modules devoted to – Identifying objects in the visual field – Controlling hands – Retrieving information from declarative memory – Keeping track of current goals and intentions • Central production system – Insensitive to activity of modules, but responds to information deposited in buffers of these modules – Each module makes information available as a chunk in a buffer ACT-R 11 • Goal buffer – Keeps track of internal state in solving a problem – Dorsolateral prefrontal cortex (DLPFC) • Retrieval buffer – Holds information retrieved from long term declarative memory – Ventrolateral prefrontal cortex (VLPFC) • Two visual buffers – Keep track of object locations • Dorsal “where” path – Keep track of object identities • Ventral “what” system • Manual buffer – Control & monitor hands ACT-R 12 • Parallelism within each module – Visual system simultaneously processes the whole visual field – Declarative system executes parallel search through memories in response to a retrieval request • 2 serial bottlenecks – Content of buffer limited to 1 declarative chunk • Only 1 memory can be retrieved at a time
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This note was uploaded on 02/14/2011 for the course PSYC 532 taught by Professor Shultz during the Fall '10 term at McGill.

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1 lecture_sept8 - ACT-R overview How does structure achieve...

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