A multi-method analysis approach is proposed to investigate whether corroborating evidence can be found to obtain some possible insights on whether intermittent interventions might increase sustained attention for a repetitive task. The proposed approach involves analysis from diverse aspects including signal detection, anomaly detection, reaction time, and workload. A small-scale experiment was conducted, in which the primary task was a low-to-moderate fidelity repetitive passport screening task, and the intermittent intervention task was an auditory task of simple calculations. Among nearly two hundred passport images, some contained incorrect information within the images, whereas some contained anomalies, such as star shapes, shown outside of the images. Results showed that the treatment group, who received intermittent interventions, showed higher sensitivity on detection errors, higher anomaly detection, without substantial differences on reaction times and workload. Results show promise on adapting the proposed approach to investigate sustained attention when developing systems for training beginners.