1. Copyright 2008 by User Interface Lab Industrial Engineering Dept. of Industrial Systems & Information Engineering Korea University Serial Modules in Parallel : The Psychological Refractory Period and Perfect Time-Sharing Psychological Review 2001 M.D Byrne & J.R. Anderson

2. Korea University User Interface Lab Copyright 2008 by User Interface Lab 2 22 순 서순 서 Introduction ACT-R PM Modeling Simple Dual Tasks - PRP, Perfect Time-Sharing Complex Dual Task - Experiment 1,2,3 General Discussion

3. Korea University User Interface Lab Copyright 2008 by User Interface Lab 3 22 Introduction Computational theory are not new to experimental psychology. Attempt to integrate cognition, perception, action MHP (1983, Card, Moran, Newell) - Cognition, Perception, Motor processor - Critical Path of dependencies among the parallel stages EPIC(1997, Meyer, Kieras) - Substantial advance in computational modeling - Simple dual task - Low level cognition( not theory of memory, problem solving, learning)

4. Korea University User Interface Lab Copyright 2008 by User Interface Lab 4 22 ACT-R/PM ACT-R + EPIC’s Perceptual - Motor Modules Spreading activation is parallel Cognition is serial Serial Production Fire Activation-based retrieval from D.M Motor Module - preparation(50ms) - execution(initiation 50ms) Vision Module - move-attention(135ms)

5. Korea University User Interface Lab Copyright 2008 by User Interface Lab 5 22 Modeling Simple Dual Task PRP (Psychological Refractory Period) - Simple choice reaction task - T2 is elevated at short SOAs (PRP effect) - SOA 0, total time < T1+T2 Response Selection Bottlenecks

6. Korea University User Interface Lab Copyright 2008 by User Interface Lab 6 22 Modeling Simple Dual Task (2) EPIC-SRD (strategic response deferment) - strategically defer responding to Task 2 - some stage of Task 2 is not allowed to proceed until it has been “unlocked” that is triggered by the completion of some critical stage of Task 1 Subadditive difficulty effects of Schumacher et al(1999) - Task 1 : tone discrimination 1120 Hz / 1450Hz (Left middle, index finger / vocal “high”, “low” ) - Task 2 : position discrimination easy : right index, middle, ring, little finger hard : right ring, index, little, middle finger

7. Korea University User Interface Lab Copyright 2008 by User Interface Lab 7 22 Subadditive difficulty effect r 2 =0.93 RMSE=18.1ms r 2 =0.91 RMSE=14.4ms

8. Korea University User Interface Lab Copyright 2008 by User Interface Lab 8 22 Explaining Subadditive Difficulty Effects(1)

9. Korea University User Interface Lab Copyright 2008 by User Interface Lab 9 22 Explaining Subadditive Difficulty Effects(2) A1. Uniform unlocking A2. Task 1 response selection & transmission A3. Task 2 response selection & transmission A4. Dual task goal Task 1 : tc+ta+tc+(nf*tf)+ti+tk=405ms Task 2 : tc+tv+r(ac)+tc+(nf*tf)+ti+tk=395+r(ac)

10. Korea University User Interface Lab Copyright 2008 by User Interface Lab 10 22 Perfect Time Sharing Lack of input interference & no output interference No peripheral interference Schumacher et al. (1997) experiment - tone discrimination : auditory-vocal task (445ms-456ms) - visual position discrimination : visual-manual task (279ms-283ms)

11. Korea University User Interface Lab Copyright 2008 by User Interface Lab 11 22 Complex Dual Task(1) PRP Arithmetic Task 1 : two auditorily presented digit - spoken answer Task 2 : single digits and addition task (6+7=12 or 6+7=13) easy : small digit / hard : large digit 1. No systematic interaction between SOA and the difficulty of the second task 2. Despite greatly increase the cognitive component – very little time sharing 3. Single task times are all reliably smaller than the dual task times 0 SOA T22400 SOA T1+T2 Easy20702362 Hard22472592

12. Korea University User Interface Lab Copyright 2008 by User Interface Lab 12 22 Complex Dual Task (2) Parallel Arithmetic Replication of PRP arithmetic No instruction regarding response order EPIC : Possible perfect time sharing ACT-R/PM : impossible because of increased cognitive demand Task 1 : Multiplication (auditory – verbal) ex) 6 * 4 = 28 Task 2 : Addition verification (visual – manual) ex) 5+3=9 incorrect

13. Korea University User Interface Lab Copyright 2008 by User Interface Lab 13 22 Complex Dual Task (2) Parallel Arithmetic EPIC : no increase in response time Both task are slow down significantly than single task SOA effect on multiplication : addition first (-SOA, easy>hard) Participant behave any differently when order is removed If cognition can go on parallel, task 2 should not be slowed No incentive for strategic deferment and no share modalities

14. Korea University User Interface Lab Copyright 2008 by User Interface Lab 14 22 Complex Dual Task (3) Fixed-Free Arithmetic Auditory stimulus was transient than visual stimulus Combining the stimulus into one visual stimulus Fixed vs Free condition - Fixed : Verification task first - Free : No order Example 3 4 7 task 1 : addition verification respond correct or false task 2 : addition or multiplication respond 10 or 21

15. Korea University User Interface Lab Copyright 2008 by User Interface Lab 15 22 Complex Dual Task (3) Fixed-Free Arithmetic No difference between addition and multiplication Slightly more often to the production task first (59%) Single task time < Dual task time (encode all aspect) Task 2 were much more slower – weak parallelism evidence Absence of any clear perceptual-motor bottleneck, task 2 was slowed substantially in both Verification result Production result

16. Korea University User Interface Lab Copyright 2008 by User Interface Lab 16 22 Complex Dual Task (4) Pattern Math Modality-specific working memory Task 1 : pattern A:4 keys, B:6 keys Task 2 : addition verification (true/false) easy: 1-4, hard:6-9 Condition : Free vs Fixed(priority pattern classification)

17. Korea University User Interface Lab Copyright 2008 by User Interface Lab 17 22 Complex Dual Task (4) Pattern Math No evidence condition effect Little parallelism in the dual task No strategic difference between fixed and free Dual task cost in both condition – unavoidable bottleneck Cognitive bottleneck rather than perceptual or motor Pattern Classification resultAddition verification result

18. Korea University User Interface Lab Copyright 2008 by User Interface Lab 18 22 ACT-R/PM Models of the Current Experiment Parallel Arithmetic Experiment - Perceive > encode > retrieve > respond - F 0.85 > 0.65 r 2 =0.98

19. Korea University User Interface Lab Copyright 2008 by User Interface Lab 19 22 ACT-R/PM Models of the Current Experiment Fixed-Free Arithmetic Pattern Math r 2 =0.96r 2 =0.98

20. Korea University User Interface Lab Copyright 2008 by User Interface Lab 20 22 General Discussion ACT-R/PM is a synthesis of computational theories ACT-R/PM can model PRP experiments including subadditive effects, perfect time sharing, dual task interference Dual task decrement – hold additional element of both task in the goal > less source activation > more retrieval time EPIC : ACT-R/PM = Parallel Cognition : Serial Cognition Cognitive Architecture : High level cognition – Low level cognition

21. Copyright 2008 by User Interface Lab Industrial Engineering Dept. of Industrial Systems & Information Engineering Korea University ? Q & A

22. Copyright 2008 by User Interface Lab Industrial Engineering Dept. of Industrial Systems & Information Engineering Korea University Copyright 2008 by User Interface Lab Thank You