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Effects of Foreknowledge and Foreperiod on Task-Switching Cost

Effects of Foreknowledge and Foreperiod on Task-Switching Cost. Myeong-Ho Sohn John R. Anderson Carnegie-Mellon University. Two Types of Control Executive (e.g., foreknowledge, expectation) Automatic (e.g., priming, utilization behavior) Task Switching Paradigm Two task sets

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Effects of Foreknowledge and Foreperiod on Task-Switching Cost

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  1. Effects of Foreknowledge and Foreperiod on Task-Switching Cost Myeong-Ho SohnJohn R. AndersonCarnegie-Mellon University ACT-R Workshop 1999

  2. Two Types of Control Executive (e.g., foreknowledge, expectation) Automatic (e.g., priming, utilization behavior) Task Switching Paradigm Two task sets Two aspects of stimulus Two responses mapped on to the same key Two steps Introduction ACT-R Workshop 1999

  3. G 7 A 4 Letter Digit Consonant Vowel Even Odd Z / ACT-R Workshop 1999

  4. Task Repetition Task Switch READY 2 sec READY 1 sec G 7 G 7 RSI 1 sec A 4 A 4 2 sec feedback feedback time ACT-R Workshop 1999

  5. Switch cost Switching tasks takes longer than repeating task. Switch cost decreases as RSI increases. Switch cost does not disappear. What is the switch cost about? Repetition priming? Less than perfect preparation for switch? Switch cost ACT-R Workshop 1999

  6. Rogers & Monsell (1995, EXP 3) ACT-R Workshop 1999

  7. Executive control Depends on foreknowledge Responsible for preparation Extent of control increases over time Apply for both repetition and switch Automatic control Depends on persisting activation of the just-performed task Responsible for repetition priming Extent of priming decreases over time Apply only for repetition, regardless of foreknowledge Two mechanisms of control ACT-R Workshop 1999

  8. Design Transition : repeat or switch Foreknowledge : blocked or random transition RSI : 200 ms, 600 ms, or 1500 ms Emphasis Experiment 1 : emphasis on STEP 1 Experiment 2 : emphasis on STEP 2 Overview of experiments ACT-R Workshop 1999

  9. Foreknowledge manipulation ACT-R Workshop 1999

  10. Prediction ACT-R Workshop 1999

  11. Experiment 1STEP 2 Latency ACT-R Workshop 1999

  12. Experiment 2STEP 2 Latency ACT-R Workshop 1999

  13. Summary of results • Blocked Repetition : no effect of RSI • Blocked Switch : faster as RSI increases • Random Repetition : slower as RSI increases • Random Switch : no effect of RSI • Emphasis did not really have any effects. ACT-R Workshop 1999

  14. Probabilistic preparation Conflict resolution Only with foreknowledge The longer the RSI, the more likely to be prepared. Compensates decreasing priming benefit. Persisting activation of instruction Base level activation With or without foreknowledge Effective when the instruction is repeated The longer the RSI, the less likely to be primed. ACT-R model ACT-R Workshop 1999

  15. ModelSTEP 2 Latency ACT-R Workshop 1999

  16. Repetition effect and foreknowledge effect are independent to each other. Residual switch cost does not seem to be under the control of executive mechanism. ACT-R can do task switching. Questions What is the process that provides the repetition benefit? Stimulus encoding? S-R mapping rules? Preparation for a switch can be perfect, then? Conclusion ACT-R Workshop 1999

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