Affect is defined as a faculty of registering pleasure/displeasure and the degree of arousal. This corresponds to the Feelings and is a guide to behaviors and to forming concepts. These behaviors and concepts are formed from a very early stage of development in each individual, often through social connections, and are not innate.
I think I am with your completely on the first paragraph, but on this one I think you're making a distinction that may be in Barrett but may not be in Epicurus as to "degree of arousal."
Also the word "affect" would appear to be Barrett (?) the term in Epicurus as to the feelings would appear to be "pathe" sometimes translated "passions" and includes both pleasure and pain (Don?) but does NOT include "degree of arousal" as part of the term pathe / passions. Obviously degree of intensity or focus is something that is relevant, but I don't gather that that factor is included under the term pathe (?)
The reason I think it is important to distinguish the two categories is that "degree of arousal" or "intensity" is a huge question that involves evaluation of the pleasure as relatively more or less desirable, and that's such a deep topic that I don't think they can be merged together. We know Epicurus said not to measure relative pleasure in terms of "time" (not the longest but the most pleasant) but as far as I know he didn't give any other measurement of intensity either, so if we're trying to be as clear as possible we ought to make clear to people that there is no absolute standard (time or anything else) telling us how to compare pleasures.
Pattern recognition is one of the ways that we have been thinking about Anticipations and I think pretty much aligns with DeWitt. It both precedes and reacts to sensations,
I think you're intending that to mean "the faculty of pattern recognition" and the issue of "both preceding and reacting to sensations" is really the question. Is it just a "faculty for recognizing patterns" that exists at birth, or is there any faint etching or disposition to etch in a particular way that is involved. Relevant quotes from Velleius include:
"For he alone perceived, first, that the gods exist, because nature herself has imprinted a conception of them on the minds of all mankind." ....
"For the belief in the gods has not been established by authority, custom, or law, but rests on the unanimous and abiding consensus of mankind; their existence is therefore a necessary inference, since we possess an instinctive or rather an innate concept of them; but a belief which all men by nature share must necessarily be true; therefore it must be admitted that the gods exist."
"For nature, which bestowed upon us an idea of the gods themselves, also engraved on our minds the belief that they are eternal and blessed."
Now it's maybe possible that this imprinting / engraving took place after birth by operation of images received after conception, but it appears a good or better chance that Velleius is talking about at birth, not exposure to images after birth.
And that's where the discussion would involve whether beavers are born with dam-building imprinted in their minds, or whether the behavior is fully learned from experience. I would think that these "instinct" questions deserve a lot of attention, because if and when it were to be reliably shown that animal brains contain etchings of any kind of behaviors, that would likely establish the principle that this could go on with humans too.
All of this is also part of what we (individually) need to take a position to as to "what Epicurus taught" as distinct from "what we think is in fact the fact the case."