Understand Human Factors

The Evolution of Human-Centered Design

Psychology is a big deal in UX design. Nearly everything is designed to fit humans, from pants pockets to electric cars, but that wasn’t always the case.

Historical Context

Before World War I

The objective was to fit the human to the machine
No consideration of human variables in design

World War I

Planes started being used in war
Suddenly, untrained soldiers had to learn how to fly
Aviation psychology was introduced
An attempt was made to mold the machine to fit the human
Unfortunately, technology wasn’t good enough yet

World War II

The sheer number of men and women needed made it impossible to choose specific people for specific tasks
Aviation design had to consider human factors (pilots’ varying skill levels)
We finally had the technology to adapt the plane to the pilot

Key Insight

If we were robots, some computer genius could just program us to be expert fliers. But we’re only human, and not everyone flying a warplane was an ace pilot.

What Are Human Factors?

The human factor describes the range of variables humans bring to their product interactions.

Common Human Factors

The most common human factors that inform design include:

Impatience - users want things quickly
Limited memory - can’t remember everything
Needing analogies - relate new concepts to familiar ones
Limited concentration - attention spans are finite
Changes in need - requirements evolve over time
Needing motivation - require encouragement to continue
Prejudices - bring existing biases
Fears - have concerns about outcomes
Making errors - humans make mistakes
Misjudgment - can make wrong assessments

Real-World Example: TL;DR

The business email shorthand TL;DR (Too Long; Didn’t Read) demonstrates human factor consideration:

Appears at the start of very long emails
Provides a short, succinct summary with only the highlights
Accounts for multiple human factors:
- Impatience - don’t want to read long content
- Limited concentration - can’t focus on lengthy text
- Need for motivation - need clear value to continue reading
- Limited memory - need condensed information to retain

Key Psychological Concepts

Mental Models

Mental models are internal maps that allow humans to predict how something will work.

Example: When you face a door, your mental model tells you:

The door can be opened
Once opened, you’ll be able to leave the room
The process of opening leads to leaving the room

A mental model breaks when expectations aren’t met (like opening a door to find a brick wall behind it).

Feedback Loops

Feedback loops refer to the outcome a user gets at the end of a process.

Example: Entering a dark room and flipping a light switch

Positive feedback - the light comes on
Negative feedback - nothing happens

The more positive feedback a user gets when completing an action, the more they will expect the outcome to be positive. The same is true with negative feedback.

Turning Limitations into Opportunities

Despite all the limitations the human factors put on UX designers, they also give us opportunities to create even better user experiences.

Nostalgia as Design Tool

Sometimes well-known brands revert their product packaging back to original designs to connect with users’ sense of nostalgia:

Potato chip companies reissuing classic bag designs from the ’80s
Century-old soda companies creating replicas of bottles from decades ago

In these cases, designers use nostalgia to connect with users - something they couldn’t use to connect with robots.

When UX designers turn limitations into opportunities, the human factor isn’t so limiting after all. The key is designing with empathy and understanding of human psychology, using these insights to create better experiences rather than exploit users.