# jzhao.xyz


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# Human Centered Design (HCD)

Last updated December 29, 2021

What drives design?

• technology-centered design: building what we are able to build but risks leaving out challenges of real people
• designer-centered design: progress made by designer’s intuition, imagining user
• user-centered design: incorporating users heavily into the desing process (e.g. double-diamond design and iterative design model)

Putting human needs, capabilities, and ways of behaving first. This requires good understanding of human psychology, technology, and good communication (both person-to-person and person-to-machine).

HCD principle is to avoid specifying the problem as long as possible but instead to iterate upon repeated approximations.

### # Importance of user involvement

Involving users helps with expectation management

• can see capabilities from an early stage
• understand better how it will affect their jobs/lives and why the features are designed that way

### # Discoverability

When we interact with a product, we need to figure out how to work it. This means discovering what it does, how it works, and what operations are possible.

This is composed up of 5 fundamental psychological concepts which are the principles of interaction:

1. Affordances: signifies what action is possible. It is the relationship between the properties of an objects and the capabilities of the user that determine how the object could be used. For example, a chair affords (“is for”) support and therefore affords sitting. If an affordance or anti-affordance cannot be perceived, some means of signaling its presence is required.
2. Signifiers: signifies where actions should occur. A mark, sound, or perceivable indicator that communicates appropriate behaviour to a person. Can be a desire paths, a push/pull label, etc. However, we shuld be aware that different cultures associate different meanings with different signifiers.
3. Constraints: limits to the possible interactions with an object. For example, the different sized holes in a scissor suggests different numbers of fingers may fit in each hole and not any more.
4. Mappings: relationship between the elements of two sets of things. For example, a mapping of light switches to light bulbs or the steering wheel to the direction of the wheels. Groupings and proximity are important principles from Gestalt psychology that can be used to map controls to function: related controls should be grouped together.
5. Feedback: communicating the results of an action or some way of letting you know that the system is working on your request. Has to be a balance, little and poor feedback and too much feedback can also be unhelpful and annoying to users. Feedback is essential, but not when it gets in the way of other things, including a calm and relaxing environment.