- The user issues instructions when performing tasks. For example, typing commands, menu option selection, touch screen, speech recognition, a combination of function keys, and etcetera. For instance, tell the time, print a file, find a photo… The main benefits of instructing are that it is quick and efficient. This mode of interaction is well suited to repetitive actions performed on multiple objects.
- Users speak or type in questions and a computer system responds with a text / speech reply as the output to the user. Examples of conversing activity models include search engines, advice giving and help systems. It is somewhat different from instructing models (which simply obey orders) in that it is more like 2-way communication. This more familiar way of interacting makes users feel comfortable and less scared. The con of the conversational model is that misunderstandings can arise when the system doesn’t know how to parse a more complex input question.
- exploring and browsing
- This model is based on a system that provides information structured in such a way to allow users to discover or learn things. Examples include CAVEs – similar to that from The Lawnmower Man – and Second Life (see whether Second Life failed or met expectations? and the benefits of using Second Life as an educational tool).
- manipulating and navigating
- Users interact and move within an environment of virtual objects and properties. For instance, the familiar scissors object found in word processing applications to perform a cutting of text. The manipulation model can exploit users’ common knowledge of how they move and manipulate objects in the real world. The term Direct Manipulation, coined in 1983 by Shneider, proposes that digital objects be designed so they can be interacted with in analogous to physical object manipulation. This assumes that interfaces enable users to feel they are directly controlling the digital object. The Wii Wheel used to control Mario Kart is a shining example of direct manipulation with immediate feedback. The drawbacks of direct manipulation include that not all tasks can be described by objects and not all actions can be done directly, some tasks such as spell checking are better achieved through delegation, and moving a mouse around the screen can be slower than pressing function keys to do the same actions.
These activity based conceptual models are potentially inclusive, i.e. they can be used together.
Then there are more specific object based conceptual models, that focus on the way a particular object or artefact is used in a particular context. In the ancient Egyptian Pharaohs’ burial chambers, treasures, pots, sarcophagus, and so on, are all artefacts of that time. A ballpoint pen is an example of a modern day artefact. When conceptualising objects for use in designs, we need to exercise extreme care in their use. Baeker et al (1995 p.583) propounds the act of artefact analysis as
carefully studying the ways that artifacts are used and understanding what features are responsible for their success and why.
The predominant conceptual models involved in a 3D video game such as Mario Kart on the Wii, are manipulating and navigating.
Described as one of the top 3 racing games for the platform, the game is controlled via Direct Manipulation of the packaged Wii Wheel providing tactile feedback, such as vibration, known as a rumble, when driving over terrain or crashing the various kart artefacts. Audio feedback comes from both, the hand-held remote for near sounds, and the system speakers. Visually, a 3D representation of the virtual race world is rendered on a regular 2D TV screen, with a third-person perspective – you can see your player in the vehicle. A semi-transparent map of the course is overlaid on the side of the screen, with additional rank and time information displayed in the corners, just like a televised car race.
The Windows virtual environment combines several conceptual models. It reuses the metaphor of the window frame and different panes to display various file types and programs that can be accessed from the computer. It also uses metaphors like the garbage bin for file disposal, and menus to make selections from. Several mental models such as the desktop as a workspace, the folders to organise files, and drag-and-drop to move files, are utilised. Navigational models including the back and forward buttons on a window toolbar, folder drill-down, search and history, are all present, particularly in more recent versions of the operating system. Instructing activities are often carried out by keyboard shortcuts (Ctrl + P instructs Windows to print). Conversing with Windows is perhaps better known to users exploiting the accessibility features of the system. Since every object you see through an operating system is virtual, we certainly spend a large amount of time manipulating and navigating within the Windows User Interface.
A modern web browser adds to the models listed above for Windows, with tabs containing separate workspaces within the one program. Bookmarks are yet another metaphor / navigation mechanism that provide fast recall of specific places. It really goes without saying that we employ the exploring and browsing conceptual models.
Downloading a file from the internet is a task probably most suited to the manipulation model of the drag-and-drop technique. This seems easier than associating an image of a downward pointing arrow and avoids confusion with other navigation hyperlinks. There could also be an instructional keyboard shortcut for frequent use and users.
Programming would generally fall into the instructing model. This could take any combination of forms, typing, speech recognition, menu option selection, function keys, and etcetera. There are several mental models, most of the metaphors are non-visual, and navigation is primarily driven by keystrokes, along with the act of coding. More than anything else, the programming language will determine which models are useful.
- Baecker R.M., Grudin J., Buxton W.A.S., and Greenberg S. 1995
- Readings in Human – Computer Interaction : toward the year 2000, Morgan Kaufman, USA