Workload

Question 1

workload

Answer 1

refers to the total amount of work or effort that a person, or group of people, is to perform within a time limit

Question 2

mental workload

Answer 2

is the amount of mental effort necessary to perform a task within a time limit
As task demands increase, or the time allowed to perform a task decreases, mental workload increases

Question 3

Why do we assess mental workload?

Answer 3

Used to maintain the workload at a level that will allow acceptable performance of operator’s tasks

Question 4

factors that contribute to workload

Answer 4

The types of tasks that the user must perform
The number of tasks to perform
Accuracy requirements
Time demands

Question 5

most current workload models are closely linked to___

Answer 5

multiple resource model. This allows HFE specialists to evaluate the extent to which specific processes are being overloaded

Question 6

empirical techniques

Answer 6

used to measure and assess workload directly in a system or simulated system

Question 7

analytical techniques

Answer 7

: used to predict workload demands early in the system development process

Question 8

The 4 major types of empirical techniques

Answer 8

Primary Task
Secondary Task
Physiological (or psychophysiological)
Subjective

Question 9

primary task measures

Answer 9

Weakest
Evaluate the mental workload requirements of a task by directly examining performance of the user or of the overall system. Not diagnostic of mental resources that are being overloaded
Not good for measuring differences in mental workload in conditions where performance shows no impairment
Assumes that as task difficulty increases, so does workload, and that performance deteriorates when workload exceeds capacity
Commonly used measures include reaction time, accuracy

Question 10

secondary task measures

Answer 10

Based on the logic of dual-task performance
User is required to perform a secondary task in addition to a primary task. Workload can be assessed by manipulating the primary or secondary task difficulty and observing changes in performance of the other task
Workload is assessed by the degree performance deteriorates on either task when performed simultaneously compared to individually
Provides a measure of the workload caused by particular combinations of tasks

Question 11

commonly used secondary tasks

Answer 11

Reaction time
Choice reaction time
Monitoring for the occurrence of a stimulus
Mental arithmetic

Question 12

benefit of psychophysiological measures

Answer 12

can provide online measurement of the dynamic changed in workload as an operator is engaged in the task, without requiring a second task

Question 13

downside of psychophysiological measures

Answer 13

require sophisticated equipment and the equipment may interfere with the primary task you’re trying to measure

Question 14

Pupillometry

Answer 14

is a technique to measure arousal by measuring the pupil diameter
The larger the pupil, the greater the workload demands
Cannot distinguish between the different resources being overloaded

Question 15

Subjective assessment techniques

Answer 15

Most important. evaluate workload by obtaining users’ judgments about their tasks
Typically ask users to rate overall mental workload or several components of workload
Relatively easy to implement
Tend to be accepted by users
Tend to be used extensively in the field

Question 16

limitations of subjective assessment techniques

Answer 16

They may not be sensitive to aspects of the task environment that affect primary task performance
Best to couple with a primary task measure
Users may confuse perceived difficulty with perceived expenditure of effort
Many factors that determine workload are inaccessible to conscious evaluation

Question 17

4 most common subjective workload assessments

Answer 17

Cooper-Harper scale
Subjective Workload Assessment Technique (SWAT)
NASA Task Load Index (NASA-TLX)
Workload Profile (WP)

Question 18

Cooper-Harper Scale

Answer 18

Used research on piloting aircraft to develop this mental workload measure
Has been modified to be applicable to a variety of settings
Yields a single measure that is sensitive to differences in workload and consistent across tasks

Question 19

Subjective Workload Assessment Technique (SWAT)

Answer 19

Initially designed for use with a variety of systems and tasks
Requires users to judge which tasks have higher workload than others using a card-sorting procedure

Question 20

Workload is divided into 3 sub-categories

Answer 20

Workload is divided into 3 subcategories:
Time load: the extent to which tasks must be performed within a limited amount of time
Mental effort load: inherent attentional demands of a task
Stress load: user variables that contribute to anxiety level

Question 21

Pros of SWAT

Answer 21

Sensitive to workload increases induced by increased difficulty of a task and difficulty caused by sleep deprivation

Question 22

Cons of SWAT

Answer 22

Not sensitive to low mental workloads
Card-sorting procedure is time consuming
Revision uses pairwise comparisons to reduce time

Question 23

NASA Taskload Index

Answer 23

Most widely used
Consists of 6 scales for users to rate workload
Mental demand
Physical demand
Temporal demand
Performance
Effort
Frustration level
An overall measure of workload can be obtained by calculating a weighting mean (by importance)