I'm still thinking of some but as of the moment, the first thing that came to my mind...

Happiness: The Pursuit of Happyness. -- the movie is not at all comedy and the likes. I prefer the overall feeling after having seen the entire movie. I remember feeling happy/inspired after watching it.

Frustration: just some movie which falls short of my expectations... like Watchmen.

Love: Fireproof! very wonderful story that gave me a deeper understanding of love.

Well, like I said, this is the best I've got as of now...  And I'll add fireproof and PoH to the OP...

If you want a movie that does fairly well for evoking emotions of sympathy, Signs.

Im pretty sure Silence of the Lambs breaks rules 1, 2, AND 3.  Congrats to you for scoring the hat trick.  I think the integral part of the movie that breaks the rules is where he removes the guard's face and wears it himself to escape from the authorities....I could be wrong.

Fear:i suggest Intensity (based on a book by Dean Koontz) (not to gory if i remember right but an exteamly good suspense movie)

you said ideas(though it may not be better) what about having them read short stories or even small books, there aregood short stories by edgar allen poe and ambroise beirce that could induce fear( tell tale heart,pit and the pendulam, The premature burial,etc and even some that could be used to stimulate the other emotions.

http://poestories.com/index.php- you can get stories here if you wish.

psychology, it fascinates me also.....

You should try classical music.

For example Mozart's Requim would serve perfectly for sadness.

You can not watch a movie and perform critical tasks at the same time. So, you should get away from the movie idea altogether. Once the subject has watched the movie, they will reset when they begin the task.

You need to introduce the emotion while they are performing the task, as your quoted statement says.

So, you need to use real people in a blind situation. Which means not telling the subject anything except that they are being tested in a specific task. Then you bring in an outside force (a person or thing) to elicit a response from the subject while they are performing their task, and measure their response and performance before, during and after the distracting event.

Here is a simple one.

While the subject is performing the task, set off a firecracker.

What emotions and responses would you expect?

While the subject is performing the task, have two people walk through the room arguing about something. The subject of the argument will evoke different emotional responses from anyone hearing it.

Anger? Discuss politics. And be sure to say you believe the counter to everything the other person does. With politics, its easy to make someone PO'ed.