Gelman responds to my post on student motivation in the comments.  He’s in blockquotes, I’m not:

First, yes, I do expect things are different at Columbia and Harvard
than at GMU, in some ways better (Ivy League students are better
prepared) and in some ways worse (teaching a GMU student might well make
more of a difference).

Actually, I was basing this on my entire educational history – K-12, UC Berkeley, Princeton, and GMU.  Berkeley and Princeton students were better-prepared than GMU students, but their motivations seemed very similar.  In fact, GMU econ undergrads are noticeably more passionate about their subject than Berkeley or Princeton econ undergrads.

Also, much depends on the subject matter. When students take a
course from me on Bayesian data analysis or survey sampling, they might
well want later to signal they’ve learned such things, but my guess it
that they really do want to learn it. I’m teaching tools that can be
used in all sorts of ways. Better to learn a tool than to signal you’ve
learned it (or, following an infinite regress, to signal that you’ve
signaled that you’ve signaled that you’ve learned it), I’d think.

student’s choice is to either:

1. Learn a tool AND signal you’ve learned it.


2. Don’t
learn a tool AND signal you’ve learned it.

…then yes, they prefer #1. 

But if their choice is to either:

1. Learn a tool AND don’t signal you’ve learned it.


2. Don’t learn a tool AND signal
you’ve learned it.

… then most students I’ve encountered strongly prefer #2.

Finally, even if the goal of taking the class is to signal that you’ve taken the class (or to signal that you had the ability to pass the class, etc), the goal of attending the lecture is not to signal but to learn the material, at least well enough to get a high grade. That is, even if you come to college to signal, you’re coming to this particular class to learn, no?

point, but don’t overstate it.  Freshman and sophomores often attend because they falsely believe that their professors are taking
attendance.  (That’s why they approach their preoccupied professors with excuses and
explanations for their absences).  Furthermore, students often correctly believe
that mere attendance will lead to marginally better grades.  Failing
students you’ve never met is psychologically a lot easier than failing
students who sit in the front row every day.