Are emotions voluntary?
Emotions are our control signals. As such, they arise from our own processing of the data we are receiving. Our emotional systems are a huge and amazing innovation that we are just beginning to understand.
Jeff Howe describes the nature and working of Decision Markets in his best selling book, Crowdsourcing: Why the Power of the Crowd Is Driving the Future of Business. And, emotions share much in common with these types of instruments. Especially in the nature of how the mind processes alternatives working easily with binary choices but often being stumped by any larger set of alternatives.
But, our minds are simultaneously evaluating each thought and each perception from four independent goal seeking value systems, you might think of these as dimensions.
Identity - How does this define me? What is me, what isn't, and my relationship with respect to others?
Affinity - How does this impact my relationships with others, my ability to seek and gain care from others, my interest in providing care to others.
Mobility/Acquisivity - How can this enable me to get or keep something I want.
Diversity - Is this interesting or boring? Relevant or a waste of time?
When we have little or no experience with the thought or event or perception, our model matching ability will often jump to a specific model and often with pronounced force and thus we can experience abnormally strong feelings and the feel the urge to act impulsively in response. Conversely, as we build up experience and multiple exposures to variations in this same situation/stimulus we have all sorts of offsetting "votes" so that our response is also much more nuanced, or even jaded.
This basic processing structure is shared by humans and higher forms of animal life.
Humans have a unique facility because of language to create "narratives" that elicit emotions "AS IF" these were real experiences. Thus we can focus on such a thought or combination of thoughts and create an offsetting "vector" or "votes" in this decision market such that the resulting emotional experience is modified from what would be appropriate for just the situation as it is presented.
Thus any adult human of normal intelligence has an emotional output equation much like this...
Emotion from perception ± Emotion from imagination = Expressed Net Emotional Response.
This is how poker players control their emotional responses, by reframing the situation, concentrating on other issues, or any number of other focal points that create a new emotional response to overwhelm or replace the "unwanted" emotional display. But, this is also key to how humans accomplish anything beyond automatically jumping to the passions of hunger, thirst, etc.. We see imaginary objects with the mind's eye and respond to them. People work for years to attain goals that are simply imaginary, but this orders their behavior and even their willingness to destroy their own health, skip means and experience discomfort and even loss or death for some of these "ideals."