Mental workload + vigilance

mental workload

a task’s demands compared to a person’s available processing capacity

workload is

unobservable

to determine workload, look for

Number of tasks + nature of tasks

Workload Measure Types

sensitive, diagnostic, not intrusive, acceptable, minimal equipment

Sensitive measure

has to pick up on task difficulty/resource demand changes for a task

diagnostic measure

tells us where the workload changes + the amount of change

non-intrusive measure

don’t want the measure to be a workload itself

acceptable

measure is acceptable to the participant

minimal equipment

equipment used doesn’t impact some’s performance

how we measure workload

primary-task performance, secondary-task performance, formal measure, physiological measure, subjective measure

primary-task performance

gives us efficiency + effectiveness of how we allocate our resources

secondary performance

measure spare capacity of our resources while performing the primary task

formal measure

uses math assessment, calculations, or task analysis

physiological measure

biological data (HR, blood pressure, cortisol levels)

subjective measure

self-report a task’s difficulty

if a change is made to task demand while in reserve capacity, there won’t be a change in primary-task performance

workload measurement issue

if a secondary task is introduced, we may not measure the demands on the task we care about

workload measurement issue

primary task demands can cause accidental effects at longer/shorter exposures (fatigue, not enough work time)

workload measurement issue

people can make strategies to do less work on a task

workload measurement issue

importance of mental workload in HF

crucial in understanding + predicting performance

vigilance

your ability to respond to things as they need responses

mackworth clock test

people had to detect clock hand skips for 2 hours

vigilance happens when (4 things)

- tasks last a long time

- have low engagement

- require you to be alert

- have weak/low frequency target signals

vigilance decrement

drop in detection of signals

decrease time on a task

fix vigilance decrement

increase target saliency

fix vigilance decrement

increase target expectancy

fix vigilance decrement

change payoffs for hits

fix vigilance decrement

create/sustain arousal levels

fix vigilance decrement

yerkes-dodson law

an even level of arousal= good performance

low arousal=

poor performance

high arousal=

decrease in attention to the task

high arousal for a simple task can

increase performance