Efficiency of program handling as a function of verbal and iconic interfaces and individual differences in ability

Differences between using a drawing program with a textual interface and an iconic interface were investigated, with a focus on interactions between abilities and interface characteristics. Subjects ( N = 81 thirteen-year-old students) used the program to copy a paper original, and measures were taken of time spent on choosing menu items and success in copying the drawing (correctness). Results from a battery of ability tests were used to form a hierarchical model of intelligence in which a general factor and specialized verbal and spatial factors were identified. The task-related parameters were then related to the ability factors in a series of LISREL (Linear Structural RELationships) models. An analysis of different components of the drawing indicated that for complex components the general factor was more strongly related to correctness in the verbal treatment. The results are interpreted to indicate the significance of general ability when transformations between subsystems for handling verbal and spatial information are demanded by the task. It is concluded that it is important to consider individual differences in cognitive abilities when comparing subjects' performance while using different interfaces. The results support the theoretical and methodological position that general and specific factors of ability should simultaneously be attended to in hierarchical models.