I'm somehow into this question. My speculation is:
An English-speaking child would first learn the word "learn" before kindergarten. He would probably learn it from his parents or playmates when they try to teach him a trick or game or life skill. Once he shows mastery in that trick/game/skill, the parent/playmate would say: "Now you learned it!" Then he got to know the past tense form "learned" implies success in learning.
Then he goes to elementary school. At the end of the first class in school, the teacher may say: "Today we studied [a subject matter]. Did you all learn it, children?" At this time, the child began to know that "studied" doesn't necessarily mean "learned" (otherwise the teacher wouldn't ask if the children all learned it) -- "studied" lacks a "success" component.
Do you agree with the above speculation?