Objectivism does not subscribe to the notion that emotions are capricious. The aphorism "emotional response" is quite accurate. An emotion is a response in that it takes what you are conscious or aware of and processes that awareness with the subconscious mind which produces the emotion.
Just as the physical senses are influenced by various factors, so the emotion is influenced. If you put your left hand in cold water and your right in hot until the temperature of your skin lowers and raises sufficiently, then pull them out and place both in a warm water - it feels warm to the cold left hand and cool to the warm right.
Emotions are influenced in a much more complex way. The ideas you have accepted over the course of your life play a role in what particular emotional response you experience.
If you believe that man is a helpless creature, driven by inexplicable forces beyond his control - chances are you will feel a sense of satisfaction seeing a movie like "The Grey" because it confirms your "sense of life".
If you understand that man is an able creature, and by understanding the forces around him can reshape nature to serve his desires, you may experience a sense of disappointment watching "The Grey" where the movie makers chose to make a movie about an emergency situation where everyone died by the end.
The online Ayn Rand Lexicon provides an entrée on emotions you may want to consider for further reading on the subject.