EVALUATING THE LAYOUT OF GRAPHICAL USER-INTERFACE SCREENS - VALIDATION OF A NUMERICAL COMPUTERIZED MODEL

We developed a numerical model for evaluation of graphical user interf ace (GUI) screens. The model consists of design guidelines concerning screen factors-element size, local density, alignment, and grouping-an d produces a complexity score for a given screen. The complexity predi ctions of the model were examined in a fully factorial experimental de sign in which GUI screens with all combinations of factors were shown to human users. We measured participants' search times for given eleme nts on all screens, and participants rated their pair-wise preferences of those screens. Overall, very well designed screens resulted in sho rter search times and high subjective preference. The combination of p oor alignment and poor local density had the strongest adverse effect on search time. Alignment and grouping were found to have more influen ce on subjective preference. Weights derived from the subjective judgm ents were introduced into the model, and a significant correlation was found between model predictions and search times. We discuss the find ings in terms of screen-design implications and in terms of the develo pment and use of numerical models in GUI design and evaluation.