Conceptual Design

• Follows requirements analysis
• Precedes physical design (e.g. screen shots showing color, fonts, white space, etc.)

The text discusses some problems of skipping conceptual design during the interaction design process (see section 2.2).

Properties of Conceptual Design

• Groups functions, operations and features
• Determines task flow or sequence of operations
• Determines user input
• Determines what output is provided to the user
• Establish use metaphors and styles of interaction
• Usually does not specify visual layout

Variants of this design phase are often called information architecture, abstract design and activity design. Once the conceptual design is completed, the back-end implementation can proceed independently (at least in principle!).

No user interface coding is allowed!

Conceptual design models

Activity-based models (sect. 2.3.1)

• Instructing. Examples include command-based and batch systems.
• Conversing. Interactive systems that carry on a dialog with the users. The systems queries depend on the user. Examples include telephone dialog systems and wizards (in MS Office products).
• Manipulating and navigating. To carry out actions, most graphical user interfaces provide objects that the user can manipulate. Immediate feedback is often provided. Usually the user can move the objects around on the screen. Examples include most word processors, PC desktops and virtual environments. Note that "navigating" refers to the space of interaction and not browsing as used with the Web.
• Exploring and browsing. Examples include a user exploring an information space such as a Web site.

Object-based models

These models more systematically develop objects and then define their properties and what actions can be performed on them. It's not always clear how these models differ from direct-manipulation models. Examples include spreadsheets and modern document-formatting programs.

Interface metaphors

Many application base the interaction on physical-life scenarios. Computer desktops typically exploit properties of real desktops (e.g. files, documents, trash can). Ideally, if the user is knowledgeable of the physical-life domain, the user's knowledge can transfer and be applied to the interactive system.

Additional conceptual design strategies

The goal is to fully explore the space of design possibilities.

• Technological determinism
• Derived from user and problem analysis
• Cooperative design (aka participatory design)
• Storyboarding
• Designer's models
• Brainstorming

Considerations for conceptual design

• Mental models
• Consistency
• Completeness

Presenting the conceptual design

• Conceptual design scenarios -- stories for how users address their problems using an interactive system, includes stories that present sequence of operations. (see pp. 260-261 for examples)
• List of design features -- may also list pros and cons
• Object-oriented -- with object responsibilities (properties and methods), may use inheritance
• Abstract sketches of screens (note that some approaches wait until the next design phase)

Discussion:

• Why should conceptual design precede physical design?
• What are additional examples of the conceptual models
• What are some advantages to instruction-based models?
• What are the costs to employing direct-manipulation models?
• What are examples of interface metaphors that fail to help the user?