👋 Welcome to Core Topic 1: Human Factors and Ergonomics!

Hello future designers! This chapter is one of the most important in the entire course because it reminds us that design isn't just about making things look cool—it's about making them work perfectly for people.

Think about your favorite chair, phone, or tool. Why do you like it? It probably feels natural, comfortable, and easy to use. This isn't luck; it's the result of applying Human Factors and Ergonomics.

In simple terms, we are learning how to measure humans so we can design a world that fits them, rather than forcing people to fit the design! Let's dive in!

Section 1: Defining the Key Terms

What's the Difference Between Human Factors (HF) and Ergonomics (E)?

Don't worry if these terms sound similar; they are closely related and often used together. They both focus on optimizing the fit between a person, the product/system, and the environment.

1. Human Factors (HF)

Human factors is the broader discipline. It is concerned with how people interact with systems and processes. It tends to focus more on the psychological and cognitive aspects.

  • Focus: The entire system, communication, decision-making, and organizational processes.
  • Goal: Reducing human error, improving efficiency, and ensuring psychological well-being.
  • Analogy: Designing a complex aircraft cockpit—HF ensures the controls are logically grouped and the pilot can react quickly to information.
2. Ergonomics

Ergonomics (often called "Ergo" in industry) is the application of human factors data, specifically relating to the physical interaction between the user and the product. It focuses on the body.

  • Focus: Physical comfort, posture, repetitive strain, and the physical interaction with tools and interfaces.
  • Goal: Maximizing physical comfort and safety, and preventing injury.
  • Analogy: Designing the physical shape of the seat and the position of the joystick in the cockpit—E ensures the pilot's back is supported and their arm doesn't get tired.

💡 Memory Trick: Ergonomics = Easy on the body (physical). Human Factors = How the mind functions (cognitive/system).

Quick Review: The Goals of HF and E

The primary aim is to maximize three things:

  1. Performance: Making tasks quicker and more efficient.
  2. Health and Safety: Reducing accidents, strain, and long-term injury.
  3. User Satisfaction: Making the product enjoyable and comfortable to use.

Section 2: Physical Ergonomics – Anthropometrics

Anthropometrics literally means "measurement of humans." This is the scientific discipline concerned with the physical measurement of the human body, such as height, weight, reach, and limb length.

1. Types of Anthropometric Data

Designers need to know more than just how tall someone is; they need to know how they move!

a. Static (Structural) Data

Measurements taken when a person is standing still or sitting in a fixed position. These measurements are simple distances between joints or points on the body.

  • Examples: Standing height, shoulder breadth, knee-to-floor height, resting hand size.
  • Use: Determining clearance (how big a doorway should be) and fixed dimensions (the height of a counter).
b. Dynamic (Functional) Data

Measurements taken when a person is performing a task or is in motion. These are often more complex as they involve movement, posture, and reach.

  • Examples: Maximum forward reach, grip strength, range of motion when seated, comfortable pushing force.
  • Use: Designing control panels, placement of handles, or assembly lines.

2. The Problem of the "Average" Person

If you design a product only for the average person (the 50th percentile), you are ignoring half the population! Since humans vary greatly in size, designers must use statistical data to ensure their product is safe and accessible to the widest possible range of users.

The Percentile Range

Anthropometric data is usually organized by percentiles. A percentile is a statistical measure that indicates the value below which a given percentage of observations falls.

  • 50th Percentile: The average person. Half the population is smaller, half is larger.
  • 5th Percentile: The measurement is only exceeded by 95% of the population. This represents the smaller or shorter users.
  • 95th Percentile: The measurement exceeds 95% of the population. This represents the larger or taller users.

Crucial Application (The Two Key Rules):

  1. For Reach & Operation (The Minimums): Design for the 5th percentile.
    Example: If the smallest 5% of users can reach a button, the rest 95% can reach it too.
  2. For Clearance & Safety (The Maximums): Design for the 95th percentile.
    Example: If the largest 5% of users can fit comfortably through a doorway, everyone can fit.

⚠️ Common Mistake Alert! Never design solely for the 50th percentile. If you design a kitchen counter height for the average person, it will be too low for tall people and too high for short people, causing strain. Designing for a range (e.g., adjustable height) is always better.

Section 3: Physiological Factors

Physiological factors relate to the study of the internal workings of the human body, especially how it responds to stress, workload, and environmental conditions.

1. Comfort, Fatigue, and Posture

The core physiological goal is to reduce fatigue (tiredness) and promote comfort.

  • Repetitive Strain Injury (RSI): Injuries caused by repeated physical movements (like typing or clicking) that can inflame tendons and nerves. Ergonomic keyboards and mice are designed to mitigate this.
  • Skeletal and Muscular Load: How much stress is placed on the bones and muscles. Good ergonomic design ensures neutral postures where muscles are not fighting gravity or unnatural angles (e.g., sitting up straight with foot support).
  • Muscle Strength: Designers must consider the maximum force a user can safely exert (e.g., designing a handle that doesn't require excessive grip strength).

2. Environmental Stressors

The physical environment significantly affects physiological comfort and performance:

  • Temperature and Humidity: If it's too hot or cold, performance drops rapidly. Designers must consider thermal comfort (e.g., ventilation in clothing, temperature control in vehicles).
  • Noise: Constant loud noise can cause hearing damage, increase heart rate, and drastically reduce concentration. Low noise can lead to boredom and poor performance.
  • Lighting: Too little light causes eye strain; too much glare can be distracting or cause headaches. Task lighting (focused light) is often necessary for detailed work.
  • Vibration: High vibration tools (like power drills) can cause significant physiological damage over time (e.g., "white finger" syndrome). Ergonomic design minimizes the transfer of vibration to the user’s hand.
Did you know? (Physiological Data)

The measure of physical work intensity is often related to oxygen consumption and heart rate. In industrial ergonomics, tasks are sometimes designed so the worker's heart rate stays within a safe, sustainable zone to prevent burnout.

Section 4: Psychological Factors

Psychological factors focus on how the mind processes information, controls movement, and reacts to sensory inputs. These are central to the discipline of Human Factors.

1. Sensory Data and Perception

Psychological Data helps us understand human memory, reaction time, comprehension, and error rates. Designers must consider how easily the user perceives and interprets signals.

  • Colour and Coding: Colours are used to communicate information quickly (e.g., red for danger, green for safe/go). Designers must use standard colour codes and consider colour blindness.
  • Light, Sound, and Touch: Products often use multiple senses to communicate. A good design might use an audible beep (sound) and a flash of light (visual) to confirm a successful action.
  • Cognitive Load: This is the amount of mental effort needed to perform a task. A product with too many confusing controls has a high cognitive load, increasing the chance of error (e.g., a complicated remote control).

Analogy: Imagine setting up a new smart TV. If the instructions are confusing and the menu layout is illogical, your cognitive load is high, leading to stress and frustration. Good design minimizes load.

2. Stress and Risk

Design affects the user's psychological state.

  • High Stress: Can lead to panic, poor decision-making, and physical reactions (like sweating palms). Often occurs in high-risk environments (e.g., air traffic control, emergency response).
  • Boredom/Low Stress: Can lead to inattention and careless errors, especially in repetitive tasks (e.g., monitoring automated production lines).
  • Risk Perception: Designers must understand how users perceive risk. If a warning label is too small, or if a sound alarm is ignored frequently, the perceived risk is low, leading to dangerous behavior.

3. Cultural and Group Differences

Our psychological response is shaped by our background. Designs intended for a global market must account for these differences.

  • Symbols and Icons: A symbol that means "OK" in one culture might be offensive in another.
  • Colour Meaning: In many Western cultures, white is associated with purity; in some Eastern cultures, white is associated with mourning.
  • Handedness: Approximately 90% of the world is right-handed. Tools must often be designed for universal use or handedness must be specified.

Section 5: Bringing it All Together – The Human Factors System

When applying Human Factors and Ergonomics to design, we must remember that a product does not exist in isolation. It is part of a system.

The Human Factors system views the world as an interaction between three core components:

  1. The Human: Abilities, limitations, physical size, mental capacity, culture, goals.
  2. The Product/Tool: The interface, controls, mechanism, materials, and form.
  3. The Environment: Light, sound, temperature, vibration, political/social context.

The designer's role is to ensure harmony between these three elements. If the environment is too loud (poor acoustics), the human will struggle to operate the product (the interface), leading to poor performance.

Designing for Inclusion and Accessibility

Good ergonomic design is often inclusive design—designing products that are usable by the widest possible range of people, regardless of age, disability, or physical limitation.

  • The Elderly: As population ages, designers must account for decreased grip strength, reduced visual acuity, and slower reaction times (e.g., larger buttons, higher contrast displays).
  • Users with Disabilities: Accessibility features are crucial, such as auditory cues for visually impaired users, or controls that can be operated without fine motor skills.

By systematically addressing anthropometrics (physical size), physiological comfort (body response), and psychological load (mind function), designers can create solutions that are safe, efficient, and truly useful.

🔑 Key Takeaway for the Chapter: Human factors and ergonomics ensure that the product is adapted to the human, not the other way around. Always design for the extremes of the user population (5th and 95th percentiles) to maximize accessibility and safety.