Ergonomically speaking, when one has a multi-task assignment, the primary task is the one that takes priority. That is, it is the task that should receive the largest amount of allocated mental and physical resource. All other tasks in the assignment are dealt with in later order.

PRIMARY TASK: "The primary task on Jim's assembly line was installing the headlights. Aiming the beam and cleaning the lens came later."
Cite this page: N., Pam M.S., "PRIMARY TASK," in, April 28, 2013, (accessed April 17, 2021).