An ergonomic pointing device, such as a mouse, includes a wheel to provide an input signal in addition to X and Y position signals provided by a rotatable ball of a standard mouse. The wheel extends from an upper surface of the pointing device and may be rotated and depressed by the finger of the user, the wheel being positioned and configured to allow a user to activate the wheel while maintaining a finger in a biomechanically neutral position. The wheel and associated structure, as well as the forces required to rotate and depress the wheel, are configured to reduce inadvertent actuation and to provide a user with tactile feedback, thereby allowing the user to accurately and intuitively activate the pointing device without exceeding an acceptable extension and range of motion for the user's finger and wrist.The mouse is coupled to a computer having a visual display device. The computer is capable of displaying a data file such as a word processing or spreadsheet document, where the data file has adjustable display characteristics such as size (zoom) or data structure (content). As a user rotates the roller, the mouse generates computer signals that are interpreted by an operating system and software applications running on the computer. The signals generated by the roller, together with a given software application, can be used in at least two ways: spatial navigation and data navigation. In spatial navigation, a user rotates the roller to cause the computer and the visual display to zoom into and out of the document and thereby display increasing or decreasing magnification levels of the document on the display. Other modes of spatial navigation allow the user to activate a roller switch, depress special function keys on a keyboard and/or move the mouse to pan, automatically scroll or manually scroll through the document. In data navigation, the user rotates the roller to view differing levels of content or detail with respect to the document.