Abstract
Task presentation concerns how information is presented. Previous studies of differences between the alphanumeric presentation and the graphic presentation of task information have reported inconclusive or inconsistent results because the effect of task structure and its interaction with task presentation have been ignored. This study explored the compatibility between task presentation and task structure. Two forms of task presentation, namely, the alphanumeric presentation and the graphic presentation, were examined. Two types of task structure, namely, linear procedural and conditional branching, were examined. A nested factorial experiment was conducted for a comprehension of computer programs. Program code written in C programming language was used as the alphanumeric presentation of computer programs. Flowchart was the graphic presentation of computer programs. 32 subjects participated, 16 being exposed only to the alphanumeric presentation, while another 16 were exposed only to the graphic presentation. Each subject performed tasks with both types of structure. Four measures were collected, task completion time, number of errors, subjective rating of task difficulty, and subjective rating of mental workload. Analysis indicated significant interaction between presentation and the structure of task on all four measures. On each measure, the graphic flowchart presentation was more compatible with the conditional branching tasks than the alphanumeric program code presentation. On the two subjective measures of task difficulty and mental workload, the alphanumeric program code presentation was more compatible with the linear procedural tasks than the graphic flowchart presentation.