Why the assumption Adam needed an experiential reference? He was created an adult. He neither needed to learn to speak, like a baby needs to learn. That is, the same argument could be used as to how Adam could have been already a cognizant being in any way, to start naming animals, for instance. Also, God would not have given Adam an instruction he had no understanding of, just as you wouldn't expect it useful to start teaching your newborn baby integral Calculus, a silly notion. Adam was created with an already developed consciousness, therefore no such ensuing mysteries, if we grasp this primal truth.
Indeed . . . Adam was promised, by the Word of God, everlasting LIFE by freely partaking of all God's providence; especially the Tree of Life which substance would cause A&E to live forever.
Adam was not a brute beast, but created in the image of God; intellectually able to comprehend the Word of God, and also recognize opposites.
With the promise given of eternal life given by God, through the provision of the Tree of Life, and the command to not partake of the Tree of the Knowledge of Good and Evil, lest he die, Adam had full understanding of God's commands and will and all promises and warnings contained therein. (Adam heard and knew the LAW of God.)
Adam KNEW, to obey God was to live, and to disobey God was to die.
So do all the seed of Adam, to this day. Even in their fallen condition, all humanity retains and possesses this inherent knowledge and moral conscience of what is really right and what is really wrong.
No man has any excuse to fail to obey God's commands and thereby sin against Righteous God. . .