Plain English Meaning

What you learn first sticks the hardest. If you learn it wrong the first time, that wrong version is what you'll fall back on later -- especially when you're stressed or rushed.

Full Definition

A principle of learning which states that the first way a skill or piece of information is learned tends to be the strongest and most lasting impression, and is therefore the version the learner will return to under pressure. Because of this, instructors must teach correctly the first time, since unlearning a wrong initial impression is much harder than learning it right from the start.

Context Anchor

Used in flight-instructor training when planning demonstrations, explanations, checklist use, radio calls, and any first exposure a student has to a skill.

Derivation

From Latin 'primus,' meaning 'first.' The principle is named for the special weight given to the first exposure to a subject -- the 'primary' learning event.