Assaying and Isolating Individual Differences in Searching a Hierarchical File System

Individual differences among users of a hierarchical file system were investigated. Results indicate that psychometric tests of vocabulary and spatial visualization are the best predictors of task performance, accounting for 45% of the variance in the data. The spatial predictor was found to be the most influential. This was dramatically illustrated by the fact that, on the average, subjects with low spatial ability took twice as long to perform the task as those with high spatial ability. Surprisingly, experience alone does not predict task performance. A comparison of the frequency of command usage between subjects with high and low spatial ability revealed that those with low spatial ability were getting lost in the hierarchical file structure. These data have implications for redesigning the software interface so as to accommodate people with low spatial ability.