The captioned type of expression in the KJV is among the most universally misunderstood in Mormon discourse. This is a natural misunderstanding. The contemporary use of familiar is as an adjective, derived from the Latin familiaris “domestic” (an adjectival formation from familia, “family”). The word means something like “intimate, very friendly.” But in about 1590 the word also began to be used as a noun meaning “demon, evil spirit.”
So in the KJV, the “one that hath a familiar spirit” does not, as commonly understood, have anything to do with “ringing a bell, prompting an impulse of recognition” or any such nuance, but rather has something to do with divination by communicating with the spirits of the dead (necromancy). KJV use of “familiar” in this sense is in my view an unfortunate translation, both for this common linguistic misunderstanding and because even if properly understood, the word conjures concepts of medieval witchcraft that are foreign to the ANE context.
The key word in Hebrew is ‘ob, which appears about 15 times in the OT. Unfortunately, we don’t really know for sure what the word means or whence it is derived. It is used in a variety of different ways. The possible meanings include a spirit, an ancestral spirit, the person controlled by a spirit, a bottle (made of skin), the ritual pit from which spirits are called up, a ghost, a demon. Most simply admit the ambiguity and admit that the word can be used in different ways: a ritual pit used by a necromancer, a spirit called up by a necromancer, and/or the necromancer himself or herself.
The word ‘ob is closely associated with the word yidde’oni. Although ‘ob appears independently (in four passages), yidde’oni always appears in connection with ‘ob (in 11 passages). Many believe the two words are always used together as a hendiadys (a rhetorical device where two nouns joined by and are meant to convey a single sense); others, including most translations, see the terms as referencing two different people, often rendered something like “medium and wizard.” In the case of yidde’oni we can recognize the root *YD’, but it is unclear whether the “one who knows” is the one consulted or the one doing the consulting.
A key text in our modern canon is 2 Ne. 26:16:
16 For those who shall be destroyed shall aspeak unto them out of the ground, and their speech shall be low out of the dust, and their voice shall be as one that hath a familiar spirit; for the Lord God will give unto him power, that he may whisper concerning them, even as it were out of the ground; and their speech shall whisper out of the dust.
This wording is clearly influenced by Isa. 29:4, which in context is talking about events in Jerusalem. This passage is a pesher, applying the Isaianic imagery to the appearance of the BoM in the last days, with speech low out of the dust. Most translations of Isaiah use some variant of “ghost” in the passage from which this wording derives, meaning a shade from Sheol. If you read this BoM passage with a proper understanding of the familiar spirit reference, it actually makes excellent sense. The words of the Book will speak low out of the dust as a ghost called up from the netherworld.