How does residual extract influence perceived sweetness?

Suppose we have two beers with the same attenuation percentage and the same percentage of fermentable and unfermentable sugars:

Beer #1:

Beer #2:

Let's also assume that 25% of the remaining extract is either unfermented fermentable extract, left over by the yeast, and 25% is unfermentable sugars (which add sweetness), and the remaining 50% is dextrins and other non-sweetening substances.

Would both beers have the same level of perceived sweetness, or would one seem drier than the other? One beer has a far higher percentage of alcohol than the other, but it also has a quantitatively greater AMOUNT (but not percentage) of residual sugar. Is the characteristic of "dryness" influenced more by residual sugars or by the percentage of alcohol?

Ignoring for the moment that "extract" means anything dissolved in the beer and assuming, based on this, that the true extract of both these beers are sugars with similar spectra then clearly the beer with the higher TE is going to taste sweeter both because of the higher residual extract and because of the higher alcohol (which is also sweetish) content.

I'm not sure I follow you. Obviously the constituents of the extract matter, because some forms of extract are perceived as sweet, while others are not. Carmelized sugars vs. dextrins, for example. But assuming the residual extract in question does contain some degree of sweet tasting extract (as every beer will), are you saying that the beer with the greater amount of total extract and the greater amount of alcohol will always taste sweeter?

So, for example, would you say that a beer such as Duvel, that starts around 1.070 and ends at 1.007 (89% attenuation, 8.3% alcohol, 1.019 residual extract) would be sweeter (i.e. less dry) than a 1.050 beer fermented to 1.010 gravity (79% attenuation, 1.017 residual extract)?

What I was trying to say is that a beer with higher alcohol content gets more sweetness from alcohol than a beer with less and that a beer with a given level of extract will taste sweeter than a beer with less, given that the sugar spectra in the extracts are the same or nearly the same. Obviously, a beer made from a highly fermentable wort (mostly maltose) but in which the yeast failed to ferment much of it will taste sweeter than a beer of equal TE in which the remaining extract is all high molecular weight dextrines.