These notes include the powerpoint slides, class notes , and the textbook (Pearson/SU. 2018. Introduction to Human Factors and Ergonomics. (1st edition).
Cape Town (South Africa), Pearson. This customised textbook is a Stellenbosch
University/Department of Industrial Psychology adaptation of: Gro...
THEME 3: COGNITIVE HUMAN FACTORS AND ERGONOMICS (HFE)
PART 1 Cognitive HFE Theory
● Apart from physical elements, most work activities also include cognitive
elements – even manual labour!
● Human activities with a high cognitive component include thinking, reading,
speaking, learning, problem solving and decision making…or interaction with a
computer.
Cognitive ergonomics is concerned with the capabilities and limitations of the human
brain and sensory system while performing activities that include a significant amount of
information processing – it considers how the human brain receives information from
the environment, processes that information, and determines appropriate responses
and actions.
Cognitive HFE has become increasingly important relative to physical HFE because of
several trends in industry and technology, including:
● Growth in the service industry sector of the economy relative to the
manufacturing sector.
● Increased use of mechanisation and automation in physical tasks previously
performed manually.
● Increased use of technologically sophisticated equipment.
The information theory
● One major problem with the design of information processing based systems
such as computers is that there is often too much information, either displayed or
required to perform the machine controls.
● Generally, the amount of information in a stimulus depends on the probability that
the stimulus carries relevant information – Shannon and Weaver 1949 -
Information theory.
Human information processing
The human cognitive processes include the following components:
● Sensory system – consists of the five senses
1
, ● Perception – follows the sensing of the external stimuli
● Memory – consists of working and long-term memory
● Response selection and execution – involves figuring out relevant action based
on perception and memory.
A model of human information processing
The Human Sensory system (sensation)
● The body receives external stimuli via sensory organs (exteroceptors) associated
with the five human senses.
● The two most important exteroceptors are the eyes (80% of human information
input) and ears (15 -19% of human information input)
The Human Sensory system – Vision (Light)
● The eye is stimulated by light.
● Light is the region in the electromagnetic spectrum that can be perceived by
human vision (the visible spectrum) which ranges from 380-780nm.
● The entire electromagnetic spectrum consists of other waves of radiant energy,
including cosmic rays, gamma rays, and X-rays among others.
Book Figure 2, page 48
2
,Visual performance is a function of various factors:
● Factors related to human visual physiology (& variability):
○ Visual acuity - capability to discriminate small objects or fine details.
○ Colour discrimination – colour sensitivity/ability to distinguish colours.
■ Monochromatism
■ Dichromatism
● Adaptation – ability to adapt to changes in light levels.
● Factors related to the light [theme 5].
● Factors related to the environment [theme 5].
The Human Sensory system – Hearing (sound)
● Hearing is the process of receiving sound.
● Sound waves typically originate from vibrating elements such as vibrating strings
(human vocal cords).
● The vibrating element creates disturbances by alternately compressing the
surrounding air on a forward movement and expanding it on a backward
movement. The disturbances then travel outward from the source as [sound]
waves.
3
, Auditory performance is a function of various factors:
● Factors related to human hearing physiology (& variability):
○ Presbycusis
○ Sociocusis
○ Nosocusis
● Factors related to the sound [theme 5].
● Factors related to the environment [theme 5]
Perception
● Perception follows the sensing of some external stimuli by the human sensory
system.
● Perception refers to the stage of cognition in which the human becomes aware of
the sensation caused by the stimuli and interprets it in the light of his or her
experience and knowledge.ie. the sensed stimuli is given meaning and
significance
Perception has two components;
1. Detection (becoming aware) and
2. Recognition (interpreting the meaning of the stimulus).
Sensation and perception – holistic understanding
● General basic concepts
○ Absolute Threshold
○ Differential threshold (Just noticeable difference)
○ Signal detection theory
○ Sensory Adaptation
○ Situational Awareness
● Visual sensation and perception
○ Perceiving forms, patterns, and objects
○ Perceptual constancies in vision
○ Misleading cues: optical illusions
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