The concept of Interaction Styles refers to all the ways the user can communicate or otherwise interact with the computer system. The concept belongs in the realm of HCI or at least have its roots in the computer medium, usually in the form of a workstation or a desktop computer. These concepts do however retain some of their descriptive powers outside the computer medium. For example, you can talk about menu selection (defined below) in mobile phones. In HCI textbooks, such as Shneiderman (1997) and Preece et al. (1994), the types of interaction styles mentioned are usually command language, form fillin, menu selection, and direct manipulation.
Command language is the earliest form of interaction style and is still being used, though mainly on Linux/Unix operating systems. These "Command prompts" are used by (usually) expert users who type in commands and possibly some parameters that will affect the way the command is executed. The following screen dump shows a command prompt - in this case, the user has logged on to a (mail) server and can use the server's functions by typing in commands.
Click to enlarge.
Figure 1: Command prompt. The command "ls- al" has just been executed
('ls' stands for 'list' and the parameters '-al' specify that the list command should display a detailed list of files).
Command language places a considerable cognitive burden on the user in that the interaction style relies on recall as opposed to recognition memory. Commands as well as their many parameterised options have to be learned by heart and the user is given no help in this task of retrieving command names from memory. This task is not made easier by the fact that many commands (like the 'ls' command in the above example) are abbreviated in order to minimize the number of necessary keystrokes when typing commands. The learnability of command languages is generally very poor.
The form fillin interaction style (also called "fill in the blanks") was aimed at a different set of users than command language, namely non-experts users. When form fillin interfaces first appeared, the whole interface was form-based, unlike much of today's software that mix forms with other interaction styles. Back then, the screen was designed as a form in which data could be entered in the pre-defined form fields. The TAB-key was (and still is) used to switch between the fields and ENTER to submit the form. Thus, there was originally no need for a pointing device such as a mouse and the separation of data in fields allowed for validation of the input. Form fillin interfaces were (and still is) especially useful for routine, clerical work or for tasks that require a great deal of data entry. Some examples of form fillin are shown below.
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Even today, a lot of computer programs like video rental software, financial systems, pay roll systems etc. are still purely forms-based.
Some points below are adapted from Shneiderman (1997) and Preece et al. (1994).
Please note that "form fillin" is not an abbreviation of "form filling". Instead, it should be read "form fill-in".
A menu is a set of options displayed on the screen where the selection and execution of one (or more) of the options results in a state change of the interface (Paap and Roske-Hofstrand, 1989, as cited in Preece et al. 1994). Using a system based on menu-selection, the user selects a command from a predefined selection of commands arranged in menus and observes the effect. If the labels on the menus/commands are understandable (and grouped well) users can accomplish their tasks with negligible learning or memorisation as finding a command/menu item is a recognition as opposed to recall memory task (see recall versus recognition). To save screen space menu items are often clustered in pull-down or pop-up menus. Some examples of menu selection is shown below.
Figure 3.A: Contemporary menu selection
(Notepad by Microsoft Cooperation)
Figure 3.B: Menu selection in the form of a webpage (microsoft.com).
Webpage in general can be said to be based on menu selection.
Some points below are adapted from Shneiderman (1997) and Preece et al. (1994).
Direct manipulation is a central theme in interface design and is treated in a separate encyclopedia entry (see this). Below, Direct manipulation is only briefly described.
The term direct manipulation was introduced by Ben Shneiderman in his keynote address at the NYU Symposium on User Interfaces (Shneiderman 1982) and more explicitly in Shneiderman (1983) to describe a certain ‘direct’ software interaction style that can be traced back to Sutherlands sketchpad (Sutherland 1963). Direct manipulation captures the idea of “direct manipulation of the object of interest” (Shneiderman 1983: p. 57), which means that objects of interest are represented as distinguishable objects in the UI and are manipulated in a direct fashion.
Direct manipulation systems have the following characteristics:
Figure 4.A: The text-book example of Direct Manipulation, the Windows File Explorer,
where files are dragged and dropped.
Click to enlarge.
Figure 4.B: One of the earliest commercially available
direct manipulation interfaces was MacPaint.
Some points below are adapted from Shneiderman (1997) and Preece et al. (1994).
