Model-Based Interface Design for Transaction-Processing Tasks

Characteristics of transaction-processing tasks are described in the context of retail point-of-sale systems (cash registers). Proliferation of functionality coupled with a lack of emphasis on interface design have led to systems that require extensive training and result in high error rates. A state-action representation of a transaction-processing task is described. This approach to task modeling is appropriate given the deterministic nature of transaction-processing tasks. To illustrate this approach, a task model for a particular retail point-of-sale system and an interface design based on this model are described. A preliminary analysis of subjects using the new interface suggests that the model-based design will result in significant reductions in training time and error rates.