Over the years many diverse approaches have evolved to study problems in human factors, typically with origins from the field of psychology. This diversification is due to the very large range of problems and multidisciplinary nature of human factors. A number of approaches (e.g. the information processing approach) focus predominantly on the behavior of human operators with less emphasis on the context or environment where work takes place. These approaches may be efficient and useful when work domains are relatively predictable, and tasks are routine and stable. However, many modern work systems are complex, have great flexibility in operation, and have unanticipated situations that require problem solving and appropriate intervention. For these systems, it is important that tasks and actions be considered in the context of the work situation. A relatively new approach based on the ecological perspective accounts for the capabilities and limitations of human operators as well as the context and environment where actions are performed. This approach provides a way of studying human operators, the work environment and their interactions within a single, coherent framework.