Input Elements

1 Guidelines For Obtaining Inputs From The User

1.1 Selecting From A Set

1.1.1 “One of Many” Choices

ften the application restricts the user to choose one item from a group of possible items. These are “one of many groups” or mutually exclusive choice groups. For instance, in a paint application the user might have a variety of tools with which to paint – a brush, a pencil, a roller, and a spray can. Even though all of these tools are available, the user may only use one tool at a time. Some examples include a list of fonts in a word processor, or the settings of the sound level.
A special case of mutually exclusive choices is the binary choice. For instance, a switch for a printer is either on or off. Another example might include a choice between one object or another object; the user can be using either printer 1 or printer 2, but not both. There are some special considerations given to binary choices; these will be pointed out below as needed.

The choice of correct interface from for mutually exclusive choice groups depending on following criteria

  1. number of times used,
  2. number of items in the group,
  3. space available on the display,
  4. frequency with which items are added or deleted from the group,
  5. nature of the attributes themselves (i.e., discrete or continuous attributes)

When using a mutually exclusive choice, you should be most sensitive to the number of times the mutually exclusive choice group is used. For example, if the user is frequently changing the attribute values (e.g., in a paint application the user might be switching paint tools frequently), do not use a dialog box. This would be too tedious. It would be better, in this case, to use a pull-down menu or a continuously displayed icon panel.

Table 1-1 presents the selection criteria in the left column and the recommended interface form in the right column. If your criteria do not fit exactly into one of the boxes on the left column choose the one that is closest to the kind of items you have. Each of the interface forms and its variants is discussed in detail below.

If Mutually Exclusive Items are… Then Use the Following Form…
attributes or values that

  • are selected frequently
  • are limited in number (2-8)
  • are best represented verbally, and
  • change rarely.
Attribute menu items
attributes or values that

  • are selected infrequently
  • are limited in number (2-8)
  • change infrequently, and
  • require little screen space.
Pop-up menu or
Drop-down list
attributes or values or objects (e.g., file names) that

  • are potentially large in number
  • are best represented verbally, and
  • can change frequently.
Single-selection lists
attributes or values or objects that

  • are selected infrequently
  • are relatively few in number (8 or fewer)
  • have sufficient screen space available, and
  • do not change.
Radio buttons
commands that

  • are selected frequently, and
  • have only two conditions.
Toggled-menu items
commands that

  • are selected infrequently, and
  • have only two conditions
Toggled-command buttons
attributes that

  • are selected very frequently
  • are limited in number
  • are best represented graphically
  • are discrete in nature, and
  • change very rarely.
Icons, icon lists, or icon palettes
attributes or values that

  • are best represented graphically, where other forms do not apply.
Specialized graphical control

Table 1-1: This table presents the conditions for selecting the proper interface form for mutually exclusive choices

1.1.1.1. Interface Forms

1.1.1.1.1. Attribute Menu Items

Attribute menu items are attributes or values (e.g., 12 Point), not commands (e.g. Rotate). Attribute menu items are located on a pull-down menu. The user picks an item by selecting the pull-down menu and moving the pointer to the desired item and selecting it. The selection mark then moves (or remains, if the same item is picked) to the newly selected items. When selected, these attributes remain in force until they are de-selected in favor of another item.


1.1.1.1.1.1. Proper Usage

* Use an attribute menu when

  • Option must be accessed frequently
  • The number of options in the group is small (i.e., no more than eight) and
  • The items in the group rarely change

Comment: There is trade off between the time it takes to find an item and the number of selections that must be made.While the optimal menu design for any is task dependent, research on menu design indicates that optimal number of items per menu group (A “group” is any number of menu items. A group on pull down menu is anything between two separators or whole list if there are no separators on pull down menu.Choice group must be offset by separators.) is between four and eight.Moreover, there is another practical consideration: As number of menu items increases, the menu gets longer. It is strongly suggested you limit your menu such that the whole menu can be displayed entirely without scroll.

The frequent (and excusable) exception to numerical limits are the “Font” and “Size” menus used in most text editors.A system may have available hundreds of fonts that the user might wish to access it regularly.Most users will have 5-20 fonts installed; these should be listed on attribute menu.Putting the list of font in scrolling list on dialogue box require a user to work more than to attribute menus.(However, a scrolling list may be acceptable if the fonts are nor regularly added and/or deleted; see below.)

The symbol used to mark the selection on the menu itself differs across platform and is discussed in section 3.1.3.2.


dgdhfhhh

  • Share/Bookmark
blog comments powered by Disqus