Preferred mental models for direct manipulation and command-based interfaces

One of the main methods used to compare direct manipulation and command-based interfaces is to examine user preferences. User preferences are extended in our research to examine which mental model, direct manipulation or command-based, subjects prefer to use in transfer situations. One group of subjects was provided with both a command-line and direct manipulation interface during a training phase. After training, several transfer experiments were conducted to determine the preferred mental model. The developed mental models were investigated by "running" the models and extending the models to new situations. They were evaluated by determining the operators specified by the subjects. By comparing the class of operators to subjects trained on only one of the interfaces, direct manipulation or command-based, the preferred model could be determined. The preferred mental model for "running" the model was the direct manipulation. For extensions that had a concrete or graphical basis in the interface, the direct manipulation was preferred. For extensions that were abstract, one model was not preferred over the other. Some ability to use multiple mental models, based upon the task, was also observed.