Modeling and analysis of human memory load in multitasking scenarios

This paper presents on-going work developing a formal framework for the model-based analysis of human-machine interaction in multiple critical systems. The framework builds on classical results from applied psychology on selective attention and working memory. The framework is intended for developers of interactive critical systems to identify plausible human multitasking strategies that are likely to be adopted by operators when using multiple interactive systems at the same time, and to estimate the memory load necessary to complete concurrent tasks. This type of analysis is especially useful at the early stages of system design, to better understand the effort necessary to operate the system when an implementation or a prototype of the system is unavailable. The analysis can also be used retrospectively, to analyse already implemented systems and complement results from user studies. An example based on infusion pumps, used in chemotherapy to infuse doses over a period, is employed to demonstrate the utility of the framework. The framework makes it possible to model the interactive tasks necessary to configure the pumps and start the infusion. The results of the analysis indicate situations where the operator is unable to carry out the task because of omission errors. These results are in line with experimental results reported in the literature, and may provide more detailed hypotheses that can be validated experimentally.