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Computer mouse

A mouse is a handheld input device for computers, involving a small object fitted with several buttons and shaped to sit naturally under the hand. The underside of the mouse houses a device that detects the mouse's motion relative to the flat surface on which it sits. The mouse's motion is typically translated into the motion of a cursor within the plane of the display.

Table of contents

History of mouse engineering

The mouse was invented by Douglas Engelbart of Stanford Research Institute[?] in 1963 after extensive usability testing. The first mouse was bulky, and used two gear wheels perpendicular to each other: the rotation of each wheel was translated into motion along one axis in the plane.

A later variation, invented in the early 1970s by Bill English[?] at Xerox PARC, replaced the external wheels with a single ball which could rotate in any direction. The ball's motion, in turn, was detected using perpendicular wheels housed on the interior of the mouse's body. This variant of the mouse resembled an inverted trackball, and was the predominant form used with personal computers throughout the 1980s and 1990s.

In a separate line of evolution, the optical mouse detected movement using an optical sensor on its underside, paired with a light emitting diode to illuminate the surface. Early optical mice could only be used on a special metallic surface (mouse pad[?]) imprinted with a grid of fine black lines. As computing power grew cheaper, it became possible to embed more powerful special-purpose image processing chips in the mouse. This advance enabled the mouse to "see" motion on a wide variety of surfaces, eliminating the need for a special mouse pad. This advance paved the way for widespread adoption of optical mice.

In contrast to the motion sensing mechanism, the mouse's buttons have changed little, varying mostly in shape and number. Engelbart's very first mouse had a single button; this was soon increased to three. Commercial mice usually had between one and three buttons, although in the late 1990s some mice sprouted five or more. The only major innovation in mouse buttons was the scroll wheel: a small wheel, with its axis oriented parallel to the mousing surface, that could be rotated "up" or "down" to provide immediate one-dimensional input. Usually, this input was translated into "scrolling" up or down within the currently selected window (see graphical user interface).

Like all input devices, mice need some connection to the host computer in order to transmit their input. Typical mice use a thin electrical cord (e.g., a RS-232 or USB cable) for this purpose. It was most likely the combination of the tail-like cord, size, and shape which led the mouse's inventors to name it as such. Cordless ("tailless") mice use wireless communication (via infra-red or radio) to transmit data.

In 2000, Logitech[?] introduced the tactile mouse, which contained a small effector[?] that made the mouse vibrate. Such a mouse could be used to augment user interfaces with haptic[?] feedback. Other unusual variants have included mice that are held freely in the hand, rather than on a flat surface, and detect six dimensions of motion (the three spatial dimensions, plus rotation on three axes). So far, these mouse exotica have not achieved widespread popularity.

Mice in the marketplace

In the 1970s, Xerox PARC included mice with its Xerox Star. Later, inspired by the Star, Apple Computer released the Apple Lisa, which also used a mouse. However, neither the Star nor the Lisa were commercially successful. Only with the release of the Apple Macintosh in 1984 did the mouse see widespread use.

The Macintosh design was influential, and its success led many other vendors to begin producing mice or including them with their other computer products. The widespread adoption of graphical user interfaces in the 1980s and 1990s made mice indispensable for computer use. By 2000, Dataquest estimated that $1.5 billion worth of mice were sold worldwide every year.

Applications of mice in user interfaces

Usually, the mouse is used to control the motion of a cursor in two dimensions in a graphical user interface. Objects, such as files, programs, or actions, are represented visually by pictures called icons and buttons; the mouse cursor can be used to select or activate such items by moving the cursor over the picture and pressing one of the mouse buttons. For example, a text file might be represented by a picture of a piece of notebook paper, and clicking on this icon might cause a text editing program to open the file in a new window. (See also point and click.)

Mice can also be used gesturally---that is, a stylized motion of the mouse cursor itself can be used as a form of input. In a gestural interface, a particular "gesture" (stylized motion) may be mapped to an action: for example, in a drawing program, moving the mouse in a rapid "x" motion over a shape might delete the shape.

Gestural interfaces are rarer, and often harder to use, than plain pointing and clicking, because they require more fine motor control of the user. However, a few gestural conventions have become widespread, including the drag and drop gesture, in which:

  • the user presses the mouse button while the mouse cursor is over an object,
  • then holds down the button while moving the cursor to a different location,
  • and finally releases the mouse button.
This motion is commonly used to move the item from one location to another---the item is "dragged" from its old location and "dropped" in its new one. For example, a user might drag and drop a picture of a file from a folder onto a picture of a trash can, indicating that the file should be deleted.

Other uses of the mouse's input are common in special application domains. In interactive three-dimensional graphics, the mouse's motion is often directly translated into changes in the virtual camera's orientation. For example, in the Quake computer game, the mouse is usually used to control the direction in which the player's "head" faces: moving the mouse up will cause the player to look up, revealing the view above the player's head.

When mice have more than one button, software may assign different functions to each button. Often, the leftmost button on the mouse will select items, and the rightmost button will bring up a menu of alternative actions applicable to that item. For example, on platforms with more than one button, the Mozilla web browser will follow a link in response to a left button click, and will bring up a menu of alternative actions for that link in response to a right button click.

One button or two?

The issue of whether a mouse should have exactly one button or more than one has attracted a surprising amount of controversy. From the first Macintosh onward, Apple always shipped computers with single-button mouse by default, whereas most other platforms used multiple-button mice by default. Apple and its advocates claim that single-button mice are more efficient, and that multiple-button mice are confusing for novice users.

Advocates of multiple-button mice point out that the lack of additional mouse buttons often leads to clumsy workarounds when more than one action may be useful for a given object. These workarounds include the following:

  • double-click
    • A "double-click" is when the user presses the button twice in quick succession. This is mapped to a separate action than a single click. For example, in the original Macintosh Finder, the user single-clicked to select a file, and double-clicked in order to open that file. Usability studies have found that the double-click is confusing and hard to use---for example, users with poor motor skills may not perform the second click fast enough, so that the action is interpreted as two single clicks rather than a single double click.
  • press-and-hold
    • In a "press-and-hold", the user presses and hold the single button, and after a certain period, the button press is not perceived as a single click but as a separate action. On Macintosh platforms, Netscape used press-and-hold to substitute for a second mouse button. This has two drawbacks: first, as with double-clicking, a slow user may press-and-hold inadvertently. Second, the user must wait while the software detects that the click is actually a press-and-hold. Furthermore, the remedies for these two drawbacks conflict with each other: the longer the lag time, the more the user must wait; and the shorter the lag time, the more likely it is that some user will accidentally press-and-hold when meaning to click.
  • key-and-click
    • Finally, the user may be required to hold down a key on the keyboard while pressing the button. This has the disadvantage that it requires that both the user's hands be engaged. It also requires that the user do two actions on completely separate devices in concert: pressing a key on the keyboard while pressing a button on the mouse.
Studies have found all of the above less usable than additional mouse buttons. Furthermore, many widely used Apple software packages, including web browsers and graphics editing programs, use one or more of the above workarounds. Critics of single-button mice point to these facts as evidence that mice should have more than one button.

See also

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