Copyright 2008 by User Interface Lab

Industrial EngineeringDept. of Industrial Systems & Information Engineering

Korea University

Serial Modules in Parallel : The Psychological Refractory Period and Perfect Time-Sharing

Psychological Review 2001M.D Byrne & J.R. Ander-son

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순 서

Introduction

ACT-R PM

Modeling Simple Dual Tasks - PRP, Perfect Time-Sharing

Complex Dual Task - Experiment 1,2,3

General Discussion

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Introduction

Computational theory are not new to experimental psy-chology.

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 solv-

ing, learning)

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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)

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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

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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

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Subadditive difficulty effect

r2=0.93 RMSE=18.1ms r2=0.91 RMSE=14.4ms

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Explaining Subadditive Difficulty Ef-fects(1)

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Explaining Subadditive Difficulty Ef-fects(2)

A1. Uniform unlockingA2. Task 1 response selection & transmissionA3. Task 2 response selection & transmissionA4. Dual task goal Task 1 : tc+ta+tc+(nf*tf)+ti+tk=405msTask 2 : tc+tv+r(ac)+tc+(nf*tf)+ti+tk=395+r(ac)

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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)

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Complex Dual Task(1) PRP Arith-metic 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 smallerthan the dual task times

0 SOA T2

2400 SOA T1+T2

Easy 2070 2362

Hard 2247 2592

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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

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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 modali-

ties

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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

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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 evi-

dence Absence of any clear perceptual-motor bottleneck, task 2

was slowed substantially in bothVerification re-sult

Production result

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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 classifi-

cation)

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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 re-sult

Addition verification re-sult

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ACT-R/PM Models of the Current Ex-periment Parallel Arithmetic Experiment - Perceive > encode > retrieve > respond - F 0.85 > 0.65

r2=0.98

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ACT-R/PM Models of the Current Ex-periment Fixed-Free Arithmetic Pattern Math

r2=0.96 r2=0.98

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General Discussion

ACT-R/PM is a synthesis of computational theories

ACT-R/PM can model PRP experiments including subaddi-tive 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

Copyright 2008 by User Interface Lab

Industrial EngineeringDept. of Industrial Systems & Information Engineering

Korea University

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Copyright 2008 by User Interface Lab

Industrial EngineeringDept. of Industrial Systems & Information Engineering

Korea University

Copyright 2008 by User Interface Lab

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