Laboratory Report 3 Essay Example | Topics and Well Written Essays - 750 words

Laboratory Report 3 - Essay Example MacKenzie & Buxton (1992) compared five width interpretation models regarding 2-dimensional targets (MacKenzie & Buxton, 1992): ï‚ ·Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   â€Å"Smaller of† model. It picks the smaller of the height and width. Intuitively it may produce accurate results, because the smallest dimension of the object will be the most restricting when attempting to move a cursor inside it. This model is only useful for rectangles. ï‚ ·Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   W’ model. It uses the length of the line between the center point of the target object and the object boundary along the approach angle. This is appealing because it is a 1-D interpretation of a 2-D task. But it is more difficult to calculate because the angle between the starting point and the target object must be known. This model is good for circles, rectangles and others. Furthermore, there are some cases that Fitts’ law failed to predict correctly. E.g., some input devices are not suited to Fitts’ Law, such as isometric joysticks that are force sensing and undergo negligible human limb motion (MacKenzie, 2001). Extensions and changes to Fitts’ Law have been proposed for some of those cases, such as Touch screens (Sears and Shneiderman, 1991), and standard GUI with lots of small target areas (such as radio button, combo buttons, and buttons on toolbars) (Sears and Shneiderman, 1991). Fitts’ Law is valid but limited. First of all, it does not address numerous factors other than target amplitude and width that affect user input performance. While there is evidence that task completion times are reduced when a task is split over two hands, Fitts Law does not address the effect of parallel strategies of delegating positioning and selecting to separate limbs. Fitts Law also does not address the effect of human body asymmetry on performance, such as the performance difference between preferred and non-preferred hands,