I agree with the previous posts, it depends a lot on the emotion and the situation. In general, I'd guess most of us (and correct me if I'm wrong, fellow INFP's) have a harder time fully expressing our emotions in front of other people--especially if they don't feel very close with those people than in private. I'd say that's pretty characteristic of our type. It has to do with introverted feeling, which is our primary function. There's also a number of other factors that go into the "equation," if you will:
1. I find that I'm much less likely to display emotions perceived as "negative" in front of others--sadness, anger, frustration, and other such feelings. Depending on the emotion this is easy or difficult to do. For example, anger and the other emotions under this umbrella like frustration, contempt, etc. is an emotion I have a much harder time tapping into than sadness or empathy. Couple that with the fact that anger often leads to conflict (which I fear and avoid like the plague), I find it easier to swallow my anger in order to preserve the peace in a situation. Sadness and all its counterparts, on the other hand, is an emotion I more readily and easily feel so I have a harder time suppressing it. I tend to be less vocal about these "negative" emotions, but I think it's still evident in my eyes. At least, my NF friends always seem to pick up on it. Either way, these are emotions that we're socially conditioned to suppress, I suppose because they're considered signs of weakness. So I tend to hold them in instead.
The problem is, as an INFP I have a very hard time "stopping" myself from feeling something. My friends who are T types, especially my NT friends, have this uncanny (at least from my perspective) ability to compartmentalize their emotions and set aside the ones that aren't useful in order to more directly and efficiently reach a solution. It doesn't mean they don't feel things. It just means they say, "this emotion isn't going to help me right now--bzzt! Switch off!" and that's that. While I marvel at their self-control, this idea is both foreign and horrifying to me. Denying my emotions is like denying who I am, and discovering who I am is the very core of my existence. I don't really relish the idea of ignoring my feelings, nor can I even imagine being marginally successful at it. Heck, I can't even get through a Disney movie without getting misty in the eyes...:blushed:
The trouble is, this bottling up of my emotions tends to lead to outbursts when I can't hold it in anymore. Sometimes I'll even unleash my contained feelings on hapless victims who weren't the ones to provoke me anyway, but more often than not I'll end up snapping at the cause. If I'm being a good and healthy INFP, then I seek a more productive and peaceful outlet for my agitation--exercise, artistic expression, writing, something like that. If I can express my feelings indirectly, that usually helps alleviate the pressure building inside.
To sum up that word vomit, I am very unlikely to express "negative" emotions, although at times suppressing them proves impossible and leads to an intense outburst that I later feel embarrassed about (though I don't necessarily regret it).
2. The previous posters have touched on this, but gender also plays a significant role. In my experience, heteronormative pressures make life very difficult for a man who is openly emotional, particularly when showing sadness or vulnerability. If a guy wants to be angry and wrathful, then he's just releasing some of that testosterone-infused masculinity. But if a man cries because you hurt his feelings, he's a whiny little pussy. Growing up, my father and my peers often told me to "man up" when I was being emotional, whereas my sisters or female friends never received the same treatment. This really only serves to reinforce the conditioning we receive not to express our emotions in public. I don't mean to imply that INFP women are more expressive, but I think it's worth mentioning that because of gender roles prevalent in society most F males have an additional obstacle to overcome--in the same way T women are pressured to be more "sensitive" because of preconceived notions about femininity. It's just another outside pressure to alter our natural tendencies.
3. Finally, I think it has to do with our cognitive functions, specifically our dominant Introverted Feeling. Forgive what will be an epically long-winded explanation, but I feel it's necessary to fully answer your question. In general INFP's experience the world internally through their feelings. It's hard to describe in a concrete way, but basically what this means is that we experience every situation we encounter in terms of how it makes us feel. My brother, by contrast, is an ENTJ. He experiences every situation in terms of the logical challenge it presents and how to most efficiently respond to the needs set out by that challenge. My mother, an ENFJ, experiences the world in terms of how she can help to facilitate a cooperative and supportive environment in which to nurture everyone's individual potential.
That's how T differs from F, which I touched on earlier, but it is also how about Fi differs from Fe. For my brother, the thinker, the focus is on logic and working with economy of resources. For my mother and me, the focus is on feelings and working towards cooperation. That seems simple enough, but there is also a difference in how my mother's Fe and my Fi function. As extroverts, my mother and brother are usually asking themselves, "how do I affect this situation?" whereas introverts like myself are more prone to ask, "how does this situation affect me?" For my mother, who utilizes Fe, that means actively using her emotions to create a harmonious and peaceful solution that makes everyone happiest. For me, this means staying in tune with my emotional response to the situation to evaluate whether or not this situation is conducive to positive emotional/personal development, and then responding accordingly. Whereas I am content to let the situation affect me and then reflect upon that, my mother feels obligated to interact with the situation in order to bring about the solution. She's constantly wondering how she makes others feel, whereas I'm paying attention to how others are making me feel.
Whew! Hopefully, that long-winded explanation of Fi in comparison to Fe helped shed light on the differences between the two. The reason I felt the need to go into such detail is that I think it explains why INFP's and other Fi types are less likely to be emotionally expressive compared to Fe types. My mother can't help but express herself because that's how she instinctively deals with the world around her. Asking an Fe individual to suppress their emotions is like asking a Te not to use logic. SYSTEM. FAIL. Introverted Feelers, however, INFP's are able to sneak under the radar much more easily. Although we experience our feelings very intensely, we internalize this feeling. We experience it inwardly, whereas Fe types express it outwardly. I don't fully understand how I'm feeling unless I'm introspecting. My mother, on the other hand, doesn't fully understand how she's feeling until she expresses it outward. For this reason, INFP's are probably less likely to express ourselves in front of others. Because of this, people often make the mistake of thinking we are "cold" or "unfeeling" when in reality there is a tempest raging under our stoic expression.
Wow. Didn't mean for that to turn into a novel, but there you have it. Sorry to bombard you with all that info but I just felt that our responses might mislead you into thinking we were less emotional than other F types simply because we were less expressive, and that's not the case. We just feel it inwardly, not outwardly.
I don't know if you're specifically interested in INFP's or F types in general, but I'd recommend posing this question in the ENFJ or INFJ forum as well if you want to hear a perspective on Extroverted Feeling from NF's. They can offer you a completely different perspective I'm sure. And since they're Fe types, they'll be really eager to help you :wink: