MENTAL WORKLOAD

Hillon I. GoaSeta A. Wicaksana

Humanika Consulting

What is Mental Workload?

Why measure it?Performance limitsPredict top performance

TasksCognitive/perceptualmultiple

Tasks with High mental workload?

High Air traffic control Pilot Military command

& control Nuclear power

plant operator anesthesiologist

N/A Computer

programmer College professor Mathematician Technical writer

Key Elements for High mental workload tasks

Stimulus driven not self paced

Large fluctuations in demand Multiple simultaneous tasks High stress/High

consequence

Workload & ArousalYerkes-Dobson law

Low arousal Low performance

Moderate arousal High performance

Over arousal Low performance

Basic approaches to measuring mental workload Analytic

Task difficultyNumber of simultaneous tasks

Task performancePrimary taskSecondary task

Physiological (arousal/effort) Subjective assessment

Measuring MWLAnalyticTracking

Queuing

SAINT

TaskUnitary

Bottle neck

Multiple

Mixed

Physiological

SubjectiveCooper-HarrisSWATNASA

Analytic Models

Tracking models predict based on systems dynamics

Queuing models predict on the basis of task co-occurrence

SAINT / microSAINT best developed queuing models

Resources/Attention Some limited capacity

Unitary: task always depletes common pool by a constant amount

Multiple: task depletes pools of resources to varying degrees

Mixed: cost of sharing even for highly dissimilar resources

Simplified HIP Model

Unconscious/Automatic Processes

Working Memory

Long

Term

Memory

AttentionS

E

N

S

O

R

Y

S

T

O

R

E

Physiological Measures heart rate: sinus

arrhythmia blood pressure respiratory rate variability tidal volume ventilation galvanic skin response evoked response

amplitude evoked response latency

evoked response latency

electroencehpalogram, spectral components time domain, flicker fusion frequency pupil diameter electromyograms electrooculograms

Subjective Workload Measures Cooper-Harris

Manual control characteristics SWAT

Dimension based instrument NASA

6-D assessment scales

TERIMA KASIH …