HFE UNIT 6 : Stress & Workload

Human Factors Ergonomic

Environmental Stressors

Physical conditions like noise, heat, cold, and vibration that affect sensory input and can impair human performance.

Psychological Stressors

Internal or situational factors such as anxiety, fear, or perceived threat that affect mental state and cognitive function.

Heat Stress

A condition caused by high temperatures resulting in dehydration, heat exhaustion, and reduced information processing ability.

Cold Stress

Exposure to low temperatures that can cause frostbite, reduced motor coordination, and impaired physical performance.

Vibration

Oscillating motion that affects posture and hand-eye coordination. High-frequency affects muscles; low-frequency may cause motion sickness.

Noise

Unwanted sound that masks auditory signals, impairs speech communication, and reduces attention and task performance.

Arousal

A physiological and psychological state of being alert; affects the level of focus and performance efficiency.

Optimum Level of Arousal (OLA)

The level of arousal at which a person performs best; higher for simple tasks, lower for complex tasks.

Cognitive Tunneling

A stress-induced condition where attention narrows excessively, causing failure to notice critical information.

Workload

The demand placed on a person’s cognitive and physical resources during task performance.

Timeline Model of Workload

A model comparing time required (TR) vs. time available (TA) to assess workload. TR/TA > 1 indicates overload.

Vigilance

The ability to maintain attention and remain alert over prolonged periods during monitoring tasks.

Vigilance Decrement

A decline in detection and attention performance during extended periods of low-stimulation tasks.

Fatigue

A reduction in physical or mental capacity due to prolonged effort, resulting in impaired performance.

Microsleep

Brief, involuntary episodes of sleep, often occurring during monotonous or prolonged tasks.

Sleep Disruption

Interference with normal sleep cycles, reducing cognitive performance and increasing the risk of error.

Task Redesign

Modifying task structure or reassigning workload to improve performance and reduce stress.

Display Design

The organization and formatting of information on displays to enhance user awareness and reduce mental load.

Workload Remediation

Techniques such as task simplification, automation, or better display design to manage and reduce cognitive overload.

Circadian Rhythm

The body’s natural 24-hour cycle that affects alertness and performance, often lowest in early morning hours.