Introduction

Numerous input devices are available for computers today. The evolution of mice root from the constant goal of creating a more ergonomic design that would not only serve the purpose of quick, easy, and accurate manipulation, but hold optimum subjective preference as well. The mouse is no longer a standard device. They have branched into multi-button manipulation, scroll capable, cordless, and reflective ( traces movement of the mouse by shooting a concentrated beam of light out from the bottom and reflecting off of the reflective surface of the mousepad).

Aside from these mice requiring similar movement from the user, more innovative input devices have also been introduced to the market that require direct-control pointing such as the lightpen and touchscreen. Although these input devices are appropriate in some situations, these are not commonly used for personal computers, due to hand-fatigue, hand-obscuring-the-screen, and higher cost.

In the design of input devices for notebook computers, it was important to keep the input device compact to fit in the small compartment, yet maintain the properties of speed and accuracy. The three most common input devices for laptop computers consist of the AccuPoint, the TouchPad, and TrackBall.

 

The AccuPoint (a.k.a. trackpoint) is composed of a small round protrusion measuring approximately 3 millimeters in diameter and sits snugly in the center of the keyboard between and slightly beneath the keys G and H. With hands in typing position, little movement is necessary to access this device. It traces movement by the amount and shift in pressure. For selection, a button is also available center below the spacebar, which is accessed easily with hands in typing position by simply extending the thumb a short distance.

The TouchPad is composed of a small touch sensitive rectangle located below the spacebar. The size of this pad does not usually exceed 5.75cm. x 4 cm. Below this, two buttons side by side are also available that serve similar purpose to that of the buttons on a two-button mouse. Selection can be made by pressing a button or tapping on the pad.

The TrackBall is composed of a small rolling ball protruding from the notebook computer. Movement is achieved by rolling the ball in the desired direction. The location of this ball varies, from below the spacebar to the side of the screen. Buttons are placed below or above the ball for easy access in a typing position.

In a study by N.P. Milner who compared various computer input devices in speed, accuracy, and subjective preference found that "under experimental conditions no single device has been found to be consistently more appropriate than any other for Human-Computer interaction (Milner)." He found that conclusions drawn from studies consistently contradict one another. He outlines the following conclusions:

• For a fixed choice, low resolution applications the most most direct input devices (e.g., a touch sensitive screen) is quickest and most liked by subjects.
• For quick and accurate selection or manipulation of high resolution objects indirect input devices are better than direct devices.
• There is no clear evidence to support the mouse, joystick or trackball as being the best high resolution indirect input device.
• In comparitive studies, cursor keys and function keys perform poorly against other input devices.
• Experimental tasks and the specific design of the input devices have a large effect on the empirical results.(Milner)

In another experiment conducted by MacKenzie, Sellen, and Buxton, where a mouse, a TrackBall, and a stylus with tablet was used to perform pointing and dragging tasks, results showed that movement times were shorter and error rates were lower in the pointing operation in respect to the dragging operation. However, for all 3 input devices, the TrackBall ranked third for both tasks. (MacKenzie, Sellen, Buxton)

Inconsistencies in results appear as we see the results of a study by Epps, who compared 6 input devices (2 versions of the TouchPad, mouse, TrackBall, and 2 versions of the joystick) in graphics editing tasks. Analysis of subjects' performance data showed better task completion times for the TrackBall and mouse (Epps).

We found no past studies on input devices used strictly for NoteBook computers. The goal of our experiment was to analyze the perfomance and preferences on the NoteBook computer input devices, AccuPoint, TouchPad, and TrackBall to see if any of these show significantly optimum results. Two Compaq computers with the TrackBall and TouchPad and a Toshiba equipped with the AccuPoint device were used. The 15 tested subjects had moderate to high computer background and have used the standard mouse as their primary input device. We hypothesized that because of the similar rolling structure of the mouse to the TrackBall, the TrackBall would be easiest to learn, with speed and accuracy, as well as highest ranked in subjective preference.

 

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