Conceptual models
A conceptual model is "a high-level description of how a system is organized and operates"
Designers have a conceptual model for their system, what it's supposed to do, and how it works. It enables "designer to straighten out their thinking before they start laying out their widgets"
Users form their own models which are based solely on interacting with the system. Their models are generally ad hoc, informal, and incomplete.
Conceptual model components
A conceptual model is built from:
- Affordances: what things can do
- Signifiers: what things look like they can do
- Constraints: what things are made not to do
- Mappings: how things relate to user's prior knowledge
- Metaphors: how things relate to user's prior knowledge
- Standards and norms: how things should be
- Instructions: what users are told to do
- Interactions: what users learn by interacting with the system
Affordances
They are the actions possible by a specific agent on a specific environment. Perceived affordances in design are what we think something is meant for and how we think we can interact with it. Any pixel on a desktop screen "affords clicking", but it's not important.
Signifiers
They are clues to understanding the product or service, some sign of what it is for, what is happening and what the alternative actions are. Our ability to perceive and decode signifiers depends heavily on prior information: past experience, familiarity and cultural clues. Note that not all signifiers are deliberate (e.g. jammed vending machine).
Constraints
They limit the set of possible actions with an object or system to make proper use more likely. This can come in the form of physical interface constraints (e.g. single sided USB) or digital constraints (e.g. confirmation dialogue).
They help make perceived affordances a subset of safe affordances.
Mapping Targets
Natural mappings reduce cognitive load on the user by making it immediately obvious which control is associated with which object.
We want to clearly communicate the target, what will control the effect, and the outcome, what the effect will be.
Standards and Norms
Standards in interface design are expectations that are binding and explicitly stated. They may be imposed by an operating system, underlying technology, or human factors research. Norms are expectations that are implicit and may be different for different cultures or groups.
Metaphors
They are ways of relating aspects of an interface to familiar objects or concepts. Makes an interface easier to understand by relying on users' specific knowledge about other domains. This is especially useful when your app's domain knowledge is too difficult to acquire or too complex.
Instructions
The only explicit way for a designer to communicate a model to the user, as well as to guide them. Should be clear, concise, and appears without prompting for novice users. Do not disrupt them, we do want it to be dismissible.