You don't need to understand how people make choices ...
... to get 80% of the way there.
Given what I've been doing with this blog, this is not the way to go for the future of macroeconomics:
The classical economic of choice is therefore far too simple as it does not capture what goes on in people’s brain when they make choices. “It is also much too static to capture the sensitivity and dynamics of the process,” [Daniel McFadden] said.
Maybe microeconomics might benefit from the study of human behavior, but macro seems to follow optimal information transfer. Optimal doesn't necessarily mean perfect, however. There is a microeconomic behavioral experiment at the beginning of the linked piece that shows a lot of information doesn't get through the market mechanism:
[McFadden] highlighted an experiment he carried out some time ago at his university where half of the students were given a chit saying they were entitled to a pencil and half did not. The two groups could trade as buyers and sellers.
While traditional economic theory said the market should clear with half the pencils sold at close to a median value. In fact less than a fifth were traded. “One answer is that people have agoraphobia – they don’t like markets and that influences resource allocation,” he said.
This brings up an interesting point about information transfer I've mentioned before (see the last paragraph). I've said ideal information transfer is the condition that the information transmitted by the demand is equal to the information received by the supply, I(S) = I(D). In real life, human rationality and behavior factors might put a limit on this so that I(S) = α I(D) for some α < 1. The thing is, α is completely unknown (at least right now). Maybe, according to the experiment mentioned, α = 2/5. This may seem like a problem for the theory, but in fact has no particular effect in any of the calculations and is essentially captured by the fitted value of "kappa" (the information transfer index). Another way to say this is that ideal information transfer might only refer to the ideal practically realizable information transfer.
To bring in an analogy with thermodynamics: there is a maximum efficiency of a Carnot cycle but this never reaches 100%. When we say we have ideal information transfer we are saying something analogous to saying we have a maximum efficiency Carnot cycle, taking that maximum efficiency to be an unknown parameter (it is fit to empirical data).
The most nihilistic way to put it is like this: if we only ever see (through a market mechanism) 2/5 of the total information available (at peak efficiency), what does it matter if that other information exists? The remaining 3/5 of the information is like an event outside of one's light cone. Saying I(S) = I(D) where I(D) is the accessible information is not mathematically different from saying I(S) = α I(D) for some α < 1.