UBC Theses and Dissertations
The effects of using icons and direct manipulation interfaces : an empirical study Lee, Robert Kar Lok
With the advancements in computing technology, applications have been developed before the true utility of the innovation is known and before appropriate testing can be undertaken to determine the best means of implementing it. Many failures in information systems have been traced to the failure of systems professionals to adequately consider the human component of the system, and the relationship between the individual and technology. The purpose of this study was to examine the performance impact of using icons and direct manipulation in human-computer interfaces. An icon based interface uses pictures or images to represent commands, objects, and system information. These images can be invoked, activated, moved by the user simply by pointing to the desired image with a device such as a mouse or a light pen. The uniqueness of how graphical information is processed in our mind provide a sound theoretical ground to suggest that icon based interfaces can improve user performance and have the ability to speed learning, when compared to non-icon based interfaces. A direct manipulation interface refers to an interface which has three unique properties:1) continuous representation of the object of interest; 2) physical actions or "labeled button presses" instead of complex syntax; and 3) rapid, incremental, reversible operations whose impact on the object of interest is immediately visible. The advantage of the direct manipulation is the fact that users are in direct control of the model world rather than working through some intermediary such as a command language. A laboratory experiment was conducted to examine the icon and direct manipulation effects. Four types of interfaces: icon based direct manipulation, non-icon based direct manipulation, icon based non-direct manipulation, and non-icon based non-direct manipulation interfaces were tested using a simple office task. Twelve subjects were randomly assigned to each of the four interface types from the 48 recruits. Each subject was required to complete three experimental sessions in two separate time periods. The independent variables were total time taken and number of actions required to complete the task, number of actions per second, number of errors made in the task, and the percentage of incorrect actions. Results show that there is not sufficient evidence to conclude icon based interfaces are better than non-icon based interfaces. However, there is a strong indication that direct manipulation interfaces are superior to non-direct manipulation interfaces in terms of time taken to perform the task and number of actions completed per second. There is also indication that over time, subjects could master the interface and perform the task more efficiently. Several directions for future research emerge from the results of the study. Redesign of interfaces, past computer experience, and extended period to measure the time effect are suggested for further research on this topic.
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