4. Discussion
The goal of this study was to find out how performance and cognitive workload are affected by different instruction methods (paper-based vs. AR-based instructions) and task complexity (high vs. low-demanding tasks) when using maintenance applications. Currently, monitoring the workload of AR system users is mainly subjective. Therefore, accurate and sensitive methodologies are required for assessing the workload of AR system users during maintenance operations. To the best of our knowledge, there are very few studies that integrate subjective and objective metrics to evaluate the mental workload of AR system users during maintenance operations. The work presented here focuses on how AR-based instruction methods with different levels of demanding tasks influence human performance and cognitive workload. The overall findings of this study mainly confirm the original hypotheses.