Threaded Cognition: An Integrated Theory of Concurrent Multitasking

1. Threaded Cognition: An Integrated Theory of Concurrent Multitasking 2010. 11. 30 산업경영공학세미나 2009572013 김재호

2. Introduction • One of the most impressive aspects of the human cognitive system is the ability to • manage and execute multiple concurrent tasks. • This space of possibilities raises an enormous challenge in understanding, on the one • hand, the human system’s astonishing capacity for multitasking and, on the other hand, • the sometimes severe limitations on multitasking performance. • In this article propose a new theory called threaded cognition that provides • a theoretical and computational framework for understanding, modeling, and predicting • performance during the concurrent execution of arbitrary tasks. • Meyer and Kieras (1997a), Navon and Gopher’s (1979), Wickens (2002) • Several theorists have posited the need for executive processes that manage and • schedule individual tasks. (Baddeley(1986))

3. Introduction • many theorists have recently turned to computational modeling as a methodology for • providing rigorous specifications of both executive and task processes. • Meyer, Ballas, and Lauber (2000) developed models in their EPIC (Executive-Process • Interactive Control) cognitive architecture. • In this article propose a theory of threaded cognition that provides both • a conceptual theory and an associated computational framework for general • domain-independent multitasking. • Threaded cognition provides a domain-independent theory and framework for • understanding, representing, and predicting multitasking performance.

4. Threaded Cognition_cook

5. Core Assumptions_Single-Task Performance • Processing Resources Assumption: Human processing resources include cognitive, • perceptual, and motor resources. • Cognitive Resources Assumption: Cognitive resources include separate procedural and • declarative resources, each of which can independently become a source of processing • interference. • Declarative Resource Assumption: Cognition’s declarative resource represents static • knowledge as information chunks that can be recalled (or forgotten). • Perceptual and Motor Resources Assumption: The perceptual and motor resources allow • for information acquisition from the environment and action in the environment. • Procedural Resource Assumption: Cognition’s procedural resource represents procedural • skill as goal-directed production rules. • Procedural Learning Assumption: When learning new tasks, declarative task instructions • are gradually transformed into procedural rules that perform the task.

6. Core Assumptions_Single-Task Performance Attend-stimulus IF the goal buffer contains a choice task and the visual resource is free and the visual buffer is empty THEN issue a request to the visual resource to encode the stimulus Respond-to-left-stimulus IF the goal buffer contains a choice task and the visual buffer contains the stimulus “O – –” and the manual resource is free THEN issue a request to the manual resource to press the index finger.

7. Core Assumptions_ Threaded Cognition and Multitasking Performance • Threaded Processing Assumption: Cognition maintains a set of active goals that produce • threads of goal-related processing across available resources. • Resource Seriality Assumption: All resources— cognitive, perceptual, and motor—execute • processing requests serially, one request at a time. • Resource Usage Assumption: Threads acquire and release resources in a greedy, polite • manner. • Conflict Resolution Assumption: When multiple threads contend for the procedural • resource, the least recently processed thread is allowed to proceed.

8. Core Assumptions_ Threaded Processing Assumption

9. Core Assumptions_ Threaded Processing Assumption

10. Relation to Other Theories of Multitasking • Threaded cognition builds on a number of existing ideas and theories and attempts to • unify them under the auspices of a single computational theory. • The most closely related theories to our own are those that attempt to integrate a • number of modalities and resource constraints into a unified framework. • Multiple resource theory (Wickens, 2002) • Contention scheduling (Norman & Shallice, 1986) • QN-MHP (Liu, 2005) • EPIC cognitive architecture (Meyer & Kieras, 1997a) • Threaded cognition arose from a unification of two recent modeling approaches by the • individual authors. • Salvucci (2005) : ACT-R (queuing and timing mechanisms) • Taatgen (2005) : dual-task performance model

11. Key Claims and Predictions of Threaded Cognition • Cognition can maintain and execute multiple active goals, resulting in concurrent threads of resource processing. • Threads can be characterized as alternating blocks of procedural processing (i.e., rule firings that collect information and initiate new resource requests) and processing on peripheral resources (including perceptual, motor, and declarative memory resources). • Processing interference can arise on the central procedural resource as well as on the declarative, perceptual,and motor resources. • Threads acquire resources greedily and release resources politely, which arises naturally from the characterization of resources as modules and buffers. • Cognition balances thread execution by favoring least recently processed threads on the procedural resource. • With practice, threads become less dependent on retrieval of declarative instructions, reducing conflicts for both the declarative and procedural resources. • Cognition requires no central or supervisory executive processes; instead, multitasking emerges from the interaction of autonomous process threads in conjunction with the key claims above.

12. Model Simulations of Representative Tasks

13. Dual Choice_ PRP and Perfect Time Sharing

14. Dual Choice_ PRP and Perfect Time Sharing

15. Dual Choice_ PRP and Perfect Time Sharing

16. Tracking and Choice_Dual-Task Interference in a Continuous Task

17. Reading and Dictation_Perfect Time Sharing in Continuous Tasks

18. Driving_Transfer and Integration in a Real-World Domain

19. Driving_Transfer and Integration in a Real-World Domain

20. Driving_Transfer and Integration in a Real-World Domain

21. Driving_Transfer and Integration in a Real-World Domain

22. Driving_Transfer and Integration in a Real-World Domain

23. General Discussion • Threaded cognition provides a theoretical and computational framework for reasoning • about and predicting multitasking behavior. • In this discussion, we expound on the broader theoretical implications of threaded cognition for concurrent multitasking and related types of multitasking behavior • Theoretical Implications for Concurrent Multitasking • concurrent multitasking does not require supervisory or executive processes to manage and schedule multiple task processes. • both procedural and declarative processes can be sources of dual-task interference and that declarative processes are an especially prevalent source of interference in the early stages of learning. • the representation of component task skills is simple and parsimonious, free from task-specific knowledge that dictates when and how task switching should occur. • because of the absence of task-specific executive knowledge, practicing two tasks concurrently results in the same performance as practicing the two tasks independently.