Are these questions in idiomatic English?

I would submit that the "affirmative forms" are also incorrect. We should say that "Psychology is the study of..."
To see if folks in the real world agree, I checked Googlefight:

"Psychology studies the": 766
"Psychology is the study of the": 10,100

Not terribly scientific, but pretty striking nonetheless. Though some folks are saying psychology studies things, they shouldn't. And we should tell them to knock it off.

I agree completely with Eric. And I hardly ever agree completely with anyone, so there!

I would recommend against both. If one is wrong, the other is also. But I would also note that my reasoning is simply that I don't see it as conventional. There's something missing in the argument that 'psychology' is inherently inappropriate as the subject of the sentence, since there are many examples where people will make non-acting nouns the subject of a sentence instead of using passive voice or awkward or more verbose phrasings. It's a pretty conventional form of shorthand. Consider:

* Psychology has come a long way since Freud.
* Pitch-bending alters the frequency of the signal.
* Democracy puts the responsibility for the future of a country in the hands of its people.
* My laptop frees me from being chained to my desk.
* Noir film captured the state of the American psyche of its time.

These are all shortcuts using some form of metonymy, but none of them make me blink twice. The second and third ones are particularly appropriate examples, since they also define the subject by making it the "actor" on its own definition. If there are 766 Google examples using "psychology studies the," then I would not be so bold as to say that it's "incorrect," but certainly it's unconventional and will raise some eyebrows. The other form ("psychology is the study of"), however, won't raise any eyebrows at all.

When the word "psychology" (and the other sciences) acts as a noun referring to a course of study, it cannot be used with a transitive verb.
The correct usage would be:
Psychology is the study of...
(where study become a noun receiving a prepositional phrase)

In simple term, how can a course of study "study" science. Only a psycologist can study.

Hey, Eric...isn't it a bummer when life just turns around and kicks you in the face?

Google:

728 English pages for "tell them to knock it off".
11,400 English pages for "tell them to stop it".

What were you saying...?

Ah, yes:

:-P

I am quite new here, but I must submit my two cents in defence of Eric's Google search, mainly because I do it all the time to justify my choice of words.

728 English pages for "tell them to knock it off".
11,400 English pages for "tell them to stop it".

This is a comparison of standard usage with idiomatic usage. Of course, the standard returns more hits.

Eric's comparison was of two standard usages.

Google doesn't tell you whether something is correct, but it certainly tells you which is more standard usage.

I am uncomfortable with psychology studying anything, by the way.

Regarding: "...psychology...cannot be used with a transitive verb."

Well, then what about "Psychology makes me uncomfortable" or "Calculus makes my head hurt"?

porsche, nobody is saying that psychology or calculus cannot be used as a subject, nor that it cannot be used as a trasitive verb (read anon. more carefully). the debate is on the use of the word study.

as a translator, i would not feel happy using it this way in my translations, but i would not waste any time trying to tell people who do to knock it off, stop it, pack it in, give it a break, call it a day or the like.

it is unnerving for many to see language change, just as it is to see your children grow into adults. but attempts to prevent either are doomed to failure.

I'd say "psychology" is the noun referring to a discipline. A discipline can't "study" something... it can only "be studied". There's a perfectly good noun referring to people "psychologists" which would be much more appropriate in all of your examples.

I'd say it's not a question of "allowed" or "not allowed"... there's no grammar fairy up the sky about to hit you with lightning for saying "Psychology studies"... and I can certainly understand what you mean, but it's a question of how much work you want your listener to have to put into understanding what you're talking about.

Please all about classification of noun form or example please write it..

"Psychology studies" tells us what psychology (or psychologists) does; "Psychology is the study of" tells us what it is. A useful distinction.

@ CeiSerith, but then why Psychology has been translated in such a kind? "Psychology studies" tells us what psychology (or psychologists) does;