Cognitive Load and Situation Awareness for Soldiers: Effects of Message Presentation Rate and Sensory Modality

We sought to determine the influence of message presentation rate (MPR) and sensory modality on soldier cognitive load. Soldiers commonly communicate tactical information by radio. The Canadian Army is equipping soldiers with a battle management system (BMS), which also allows them to communicate by text. We varied presentation modality (auditory vs. visual) and MPR (fast or slow) in an experiment involving a tactical scenario. Participants (soldiers) received messages and periodically provided situation reports to higher level command, and the scored reports were used to provide a measure of situation awareness (SA). The detection response task (DRT) and NASA-TLX were used to measure cognitive load. The fast MPR reduced DRT accuracy and increased response times relative to slow MPR. The NASA-TLX results also showed higher subjective workload ratings for several subscales with fast MPR. Messages presented visually produced greater cognitive load, with slower DRT response times for the visual than the auditory condition. SA scores were higher with slower MPR and auditory presentation. There was no statistical interaction of presentation modality and rate for any measure. Fast MPR and visual presentation increased cognitive load and degraded SA. These findings show that the DRT can be used to measure workload effectively in a tactical military context and that the method of information presentation affects how soldiers process information in a BMS