Psychology in Design – Human Factors Overview

Historical Context of Human Factors in Design

• Before World\ War\ I (early 1900s)

  • Dominant mindset: “Fit the human to the machine.”

  • Little to no consideration of user abilities, limits, or psychology.

• Shift during World\ War\ I

  • Introduction of aviation required untrained soldiers to fly.

  • Emergence of Aviation Psychology: first systematic attempt to adapt machines (aircraft) to human capabilities.

  • Technology, however, was still too primitive to fully implement human-centric changes.

• Acceleration in World\ War\ II

  • Massive scale of war effort made it impossible to assign the “perfect” person to each task.

  • Design necessity: Planes had to accommodate pilots with a wide range of skill levels and experience.

  • Technological advancements finally allowed meaningful adaptation of cockpit layouts, controls, and feedback to pilots.

Defining “Human Factor”

• Encompasses all variables humans bring to an interaction with a product, service, or system.

• Variables include physical limits (reach, vision), cognitive limits (memory, attention), emotional states, cultural expectations, and learned behaviors.

• Core idea: Instead of forcing humans to adapt to machines, we design machines (or digital products) around humans.

Common Human Factors Designers Must Consider

• \textit{Impatience}: Users expect rapid results; latency feels longer than it is.

• \textit{Limited\ Memory}: Short-term memory holds roughly 7 \pm 2 items (Miller’s Law) – drives minimalistic UI and chunking.

• \textit{Need\ for\ Analogies}: People rely on existing mental models; unfamiliar concepts need metaphors or skeuomorphic cues.

• \textit{Limited\ Concentration}: Attention spans are easily disrupted; clear visual hierarchy and progressive disclosure help.

• \textit{Changing\ Needs}: Context, goals, and capabilities shift over time or across environments.

• \textit{Need\ for\ Motivation}: Rewards, progress bars, and affirming micro-copy keep users engaged.

• Prejudice/Bias: Prior beliefs affect interpretation of new information (confirmation bias, status-quo bias).

• \textit{Fears}: Security warnings, irreversible actions, or unfamiliar processes can trigger anxiety.

• \textit{Propensity\ for\ Errors}: "To err is human"; systems must prevent, detect, and allow recovery from mistakes.

• \textit{Misjudgment}: Overconfidence or heuristics (e.g., anchoring) lead to sub-optimal choices.

Real-World Illustration: “TL;DR” in Email

• Acronym stands for “Too Long; Didn’t Read.”

• Placed at the top of lengthy emails to provide a concise summary.

• Addresses multiple human factors simultaneously:

  • \textbf{Impatience} → Quickly surfaces key info.

  • \textbf{Limited\ Concentration} → Reduces cognitive load.

  • \textbf{Need\ for\ Motivation} → Lowers perceived effort; user feels rewarded by instant clarity.

  • \textbf{Limited\ Memory} → Highlights must-remember items, letting details be referenced later.

• Demonstrates how four little letters turn limitations into a valuable design convention.

Key Psychological Concepts for UX Design

Mental Models

• Definition: Internal cognitive representations users form to predict how a system works.

• Design Implications:

  • Align interfaces with widely held models (e.g., trash-can icon for delete).

  • Provide clear cues when the system diverges from expectations.

Feedback Loops

• Definition: The response a system provides after a user action, informing whether the action succeeded or failed.

• Basic structure: Action \rightarrow System\ Response \rightarrow User\ Interpretation

• Design Implications:

  • Always supply timely, unambiguous confirmations: sounds, haptic taps, animations, or messages ("File uploaded ✔️").

  • Lack of feedback breeds uncertainty, errors, and abandonment.

Turning Limitations into Opportunities

• Human constraints can inspire richer, more resonant experiences.

Ethical & Practical Considerations

• Respect user cognition: Do not exploit biases to manipulate decisions unethically.

• Error tolerance: Design safety nets (undo, version history) acknowledging inevitable human mistakes.

• Inclusivity: Different populations (age, ability, culture) exhibit varied mental models and limitations; one-size-fits-all fails.

• Continuous adaptation: Human factors evolve with technology (e.g., shrinking attention spans with mobile usage).

Key Takeaways

• The human factor shifted design philosophy from machine-centric to user-centric, spurred by wartime necessity.

• Understanding psychological traits like impatience and limited memory guides UI decisions.

• Core constructs––mental models and feedback loops––must be honored to prevent frustration and build trust.

• Human limitations, such as susceptibility to nostalgia, can be reframed as creative opportunities, enriching experiences rather than constraining them.