## 6 Discussion
### Cognitive Workload Measurement--Interruption Management Strategies  
The results analyzed in previous sections indicate that when peripheral tasks interrupt the ongoing processing of primary tasks, users experience more irritation and anxiety, need more time to complete the tasks, and make more mistakes across tasks. These adverse effects are worse when the types of tasks are dissimilar between the primary and peripheral tasks. [PERSON] et al. [63] investigated the frequency effect of interruptions and content relevancy between primary and peripheral tasks. Then, they found that the negative impact of interruptions on task performance was more severe when the contents of both tasks were dissimilar. As more diverse notifications and interventions are implemented in modern workplaces, unavoidable immediate interruptions increasingly occur, and the collective effect of these interruptions can be quite notable. The data showed that interruption costs are taken as a negative implication that increase workload and lower work performance; such an estimate of negative effects would be useful in modern working environments. Considering unavoidable and widespread features of interruptions, the evaluation of interruption cost might allow users to determine how interrupting peripheral tasks should be handled. The different ways of interruption interaction may help identify the optimal way of presenting the information or sequencing peripheral tasks based on the user's workload levels. Because the interruption coordination modes considered in this study manipulated timings and types of interruption onset, our results can lead to the development of temporal strategies for reducing the interruption cost. By deferring delivery of imminent peripheral tasks to lower mental demanding moments during task execution, the resulting outcomes of the interruption would be significantly less disruptive. As shown by our results, the control of interruption delivery could lead to a large alleviation of disruptive effects. This study suggested three approaches to measure interruption costs in terms of workload assessment. Firstly, the performance-based measure assumes that successful behavioral outcomes mirror workload and that poor performance is a good indicator of workload. Performance measures with task completion time and task accuracy capture how well the user is performing a given task. Secondly, the self-reporting subjective perception measure using the NASA TLX questionnaire also assumes that an individual can correctly identify and report changes in workload. However, both approaches have limitations. Workload measured by behavioral and self-reported outcomes is a snapshot rather than a continuous measurement. Because the self-reported measure is conducted after the task is performed, the measurement is mainly reflected by most recent effects. In addition,the performance-based measure is mainly limited to a laboratory environment; thus, the results would be difficult to demonstrate in a real-world experience. To complement the limitations of subjective and task performance measures, a physiological approach based on pupil diameter data is suggested. With advances in sensor technology, physiological metrics can produce continuous estimates in real time and overcome the limitations inherent in subjective measurement or behavioral performance. In particular, as shown in this study, the pupillary dilations accompanying cognitive processes are taken as a representative function of mental effort in performing the cognitive task. However, physiological measures depend on many factors, including other aspects of the user's cognitive state, the user's physical activity, and environmental variables such as temperature and lighting [64]. While subjective measures are relatively simple to oversee, they cannot account for rapid changes in cognitive load that may be the result of changes in experimental conditions.