Psychological Factors in Design
Understanding Psychological Factors
The Complexity of Human Psychology
- Human psychology is complex and varied.
- Designers often struggle to classify people into groups because:
- Psychological traits are broad and may not apply to everyone.
- Data on touch, taste, and smell are often subjective.
Design permeates every aspect of human experience, making it essential to consider psychological factors.
Key Aims for Designers
- Analyze the human information processing system.
- Identify potential breakdowns and their effects.
Focus on how psychological factors influence user interaction with products.
Collecting Psychological Data
Designers use various methods to gather psychological data:
- Interviews: To understand beliefs and experiences.
- Surveys: To collect consistent data from multiple participants.
- Observation: To see how users interact with products in real-time.
- Standardized Tests: To measure performance or ability.
Nominal Scale
- Purpose: Categorizing the survey-taker into groups
- Examples: Which city do you live in? / What is your gender?
- Characteristic: No numerical value, factual e.g., not an opinion
Which city do you live in:
- London
- New York
- Tokyo
- Hong Kong
- Other
Ordinal Scale
- Purpose: Only to show order / ranking only
- Examples: Satisfaction levels (unhappy to happy).
- Characteristics: It's to figure out ranking and not intensity or difference e.g. someone who rates themselves a 5 on most satisfied is not necessarily 5 times happier than someone who rated themselves a 1
A survey asking users to rank their satisfaction from 1 (least satisfied) to 5 (most satisfied) uses an ordinal scale
... kind of like if you scrolled to the end of this article and told us how much you like /dislike this with our emoji system :)

Interval Scale
- Purpose: Shows both the order and the difference but no absolute zero
- Examples: Celsius temperature on a thermometer
- Characteristics:
- No absolute zero - on a thermometer we only set 0 degrees as "zero" because it's the freezing point of water
- The point is that 10 degrees is warmer (as it's a bigger number) than 0 degrees, and that the difference between 10 and 0 is the same interval as the difference between 20 and 10
The interval difference between 10 to 20 degrees is the same as between 15 to 25 degrees.

Ratio Scale
- Purpose: Comprehensively order, differences and has absolute zero
- Examples: Weight, speed.
- Characteristics: Absolute zero, equal intervals and ordered
Ratio scales provide the most detailed quantitative data.
