Physiology, Psychology
& the Senses
Understand how physical capabilities and sensory processing shape product interaction.
By the end of class, you should be able to…
Explain physiology
Relate physical capabilities and limitations to product interaction.
Use required factors
Explain visual accuracy, colour perception, strength, fatigue, muscle control and hearing thresholds.
Explain psychology
Connect human senses and perception to design decisions.
Apply multisensory design
Discuss how smell, sound, touch, taste and vision can influence products.
Physiology asks what the body can do.
Designers should consider capabilities, responses and limitations during real tasks.
Visual accuracy + colour perception
Legibility, target size, contrast and colour coding can affect successful use.
Force over time
A task that is possible once may become difficult after repetition.
Precision + coordination
Small controls, fine movement and stability can change who can use a product reliably.
Detecting sound
Alerts and feedback must be perceivable in the intended environment.
Can users see enough detail to act correctly?
Small details demand precision
Tiny labels, icons or touch targets may increase error for some users.
Context changes visibility
A display that works at 30 cm may fail across a room.
Signal must separate from background
Visual clarity can support faster, safer interpretation.
Colour is not enough
A safety control uses a red light for “stop” and a green light for “go,” but the two indicators are identical in shape and position.
What is the strongest improvement?
Strength, fatigue and muscle control affect the same task differently.
Designers should separate maximum capability from sustained, precise performance.
Can the user generate enough force?
Opening, lifting, squeezing or turning may exceed capability.
Can performance be sustained?
Repeated or prolonged force can reduce effectiveness and increase error.
Can the movement be precise?
Fine motor tasks and unstable positions may need larger targets or different mechanisms.
An audible signal competes with the environment.
A soft confirmation tone may work.
Low background noise can make a subtle signal perceivable.
The same tone may disappear.
Noise, hearing ability and distance affect whether the signal is detected.
Psychology studies how information reaches and is interpreted by the mind.
The syllabus explicitly includes all five senses as possible influences on product design.
Vision
form, colour, hierarchy, status
Sound
alerts, confirmation, quality cues
Touch
texture, temperature, grip, haptics
Smell
freshness, warning, atmosphere
Taste
food-contact and consumption experience
A cue is useful when the user can interpret what it means.
| Sense | Design example | Purpose |
|---|---|---|
| Touch | Raised marker on a control | Locate / distinguish without looking. |
| Sound | Click when a lid locks | Confirm successful closure. |
| Vision | Progress bar + status icon | Communicate state over time. |
| Smell | Odour in safety / freshness context | Signal condition when appropriate. |
| Taste | Food-contact material / geometry | Influence consumption experience. |
Which design is more robust?
A microwave completion signal must work for users in a noisy shared kitchen and for users who may not hear the tone clearly.
Which response uses human factors best?
Redesign one feedback moment.
Choose a timer, door lock, charging device, appliance control or classroom tool.
Human capability vocabulary
Retrieve first. Then check.
Can you retrieve it without looking back?
Anthropometrics + physiology + psychology answer different questions.
What are the dimensions?
Reach, height, breadth, movement range.
What can the body do?
See, hear, exert force, sustain effort, control movement.
How is information perceived?
Sensory cues, interpretation and response.
Before you leave…
Inclusive Design & Designing for Extremes
Keep the evidence chain moving: user → research → decision → test.
A1.1.6 physiology: visual accuracy, colour perception, strengths, fatigue, muscle control, hearing thresholds · A1.1.7 psychology and the senses: smell, sound, touch, taste, vision.