2.3 Subjects/Experiment Design

36 subjects with at least 5 hours of Windows or GUI-based OS experience were recruited. The subject pool consisted of 8 females and 28 males. The mean age for all subjects was about 27 years, with the youngest being 16 years and the oldest 54. All subjects had more than sufficient ability to properly manipulate and navigate through the various interfaces.

The subject pool was split into two groups of 18. Each subject was given six tasks where the thumbnail size was fixed, and the interface type was varied. The order of task and interface was mixed between each subject in order to balance any biases inherent in the experiment design. Two sets of measurements from each interface type were observed per subject, giving 36 sets of measurements for each combination of independent variable treatments (see A.1). This meant that each subject in a given group of 18 tried all three interface types, but with only a 3x3 or a 5x5 grid size.