In a very helpful essay on “The Adequacy of Human Language” J. I. Packer says that Jeremiah 1:9 (“I have put my words in your mouth”) provides the “theological paradigm” of what is involved in inspiration: “God causes His message to enter into a man’s mind, by psychological process that are in part opaque to us, so that the man may then faithfully relay the message to others.”
He points out that inspiration took different psychological forms for different writers at different times:
The dualistic inspiration of prophets and seers produced in them a sustained awareness of the distinction between their own thoughts and the visions and specific messages that God gave them.
This is psychologically different from the state of mind resulting from the didactic inspiration of the biblical historians, wisdom teachers, and New Testament apostles. For them the effect of inspiration was that after observation, research, reflection, and pray they knew just what they should say in God’s name, as witnesses and interpreters of His work.
Also, it is psychologically different from the lyric inspiration of the poets, who write the Psalms and the Song of Songs in responsive celebration of what they had come to know of God’s goodness in creation, providence, and redemption. Subjectively, as all versifiers and hymn writers know, the experience of a poem “coming on” (cf. Pss. 39:3; 45:1), of its gradually taking form in consciousness, differs both from the way in which an oracle is received and from the way didactic certainty is given.
But—and this is the point to note—in the Bible writers’ view, which almost all the church shared from apostolic days until quite recently, the theological reality of inspiration is the same in each case. God so controlled the process of communication to and through His servants that, in the last analysis, He is the source and speaker not merely of biblical prophecy but also of biblical history, wisdom, and doctrine, and also of the poems, whose giant-size delineations of adoration and devotion set worshipers of every age a standard for what their own praise and prayer should be. . . .
Whether spoken viva voce or written, and whether dualistic or didactic or lyric in its psychological mode, inspiration—that divine combination of prompting and control that secures precise communication of God’s mind by God’s messenger—remains theologically the same thing.
—J. I. Packer, “The Adequacy of Human Language,” in Inerrancy, ed. Normal L. Geisler (Grand Rapids, MI: Zondervan, 1980), pp. 198, 199; emphasis added.
You can find a helpful outline summary of Packer’s article here.