To support the landed soldier during operational missions in hostile environment, equipment must be designed to enable soldiers to cope with strong visual, auditory and informational demands. Technological solutions proposed by manufacturers are embodied in increasingly sophisticated systems.

These systems take too little account of the characteristics of the perceptive and cognitive skills of human beings in an action situation.

Cognitive load results from the interaction between, on the one hand, the characteristics of the task and the constraints it imposes, and on the other hand, the resources available to the individual, in terms of skills, motivation, physiological state and social support. The phenomenon of cognitive overload occurs when the individual no longer has sufficient resources to meet the demands of the task, which leads to a deterioration in his performance which, in high-risk situations, jeopardizes his safety.

Tasks are treated differently depending on their level of difficulty. We will base ourselves on Rasmussen's SRK (Skill Rule Knowledge) model, which describes three levels of information processing: level S refers to the (automatic) processing of sensory-motor and cognitive skills, level R refers to the execution of rules and procedures embedded in mental models, and level K refers to the mental activities of elaborating procedures, based on high-level cognitive mechanisms, such as anticipation, evaluation or planning. Multitasking situations are therefore generally composed of tasks of various levels of difficulty which lead to a higher or lower cost of cognitive control.

Thus, this study is aimed at identifying variations in the subjective level of cognitive load of landed combatants (group leaders) as a function of the level of difficulty of primary tasks.

Inclusion Criteria:

• to be a soldier in an infantry regiment,
• to be a group leader.

Exclusion Criteria:

• to be in a situation of motor disability,
• to have a cardiac pathology,
• to have a visual pathology not corrected by glasses or contact lenses,
• to have a hearing impairment,
• to have a psychiatric disorder; a progressive neurological or organic pathology requiring drug treatment,
• to take psychotropic drugs,
• to take more than 28 units of alcohol per week,
• to be epileptic.

The study population is composed of healthy soldiers serving as group leaders in an infantry regiment.