First we get we're somebody: self-awareness. Later, we get that who we present to people isn't completely who we are: 'the social face' as different from your 'true self.' How discrete are the two, though? I believe that what we choose to project is still part of our true selves - both separate and part of who we are.
What separates me feeling something (anger, say) and the actor performing that same feeling/experience is primarily the reason is was prompted. The difference is just the catalyst for the experience - me feeling anger is the same as the actor feeling angry. What is different is that I was betrayed (prompting anger), and the actor was not, but is compelled by the situation (and their choice) to feel betrayed and angry.
Of course there are other aspects that effect the actor's performance - which I say to concede a difference in the 'amount of anger felt;' a real-life outburst has effects that reverberate into your memories, relationships with others, etc.) - but are they feeling angry at that moment? The actor is in turmoil, gnashing his teeth - his body is expressing anger.
How to Feel Repulsed
To snarl a phrase at someone, you have to (Well) snarl it. Your snarling (TRY IT!) - even you beginning to pull up the side of your lip to snarl a word while reading this - that motion makes it notably easier to say the word in a way that makes it sound like you are repulsed. The movement triggered the feeling: external action prompted internal feeling.
This ties in with research that choosing to express something - even a facial expression - moves that individual's mood/feelings in the direction of what was expressed - smiling, frowning, frightened - whether or not it was prompted by a legitimate event that caused the expression.
Which brings me back to the difference between me feeling angry and the actor expressing/feeling anger: what caused it. The difference is outside of the individual's experience at that moment.
You, Even if it Isn't
'The social face' we put on is a performance. Though we might hold our cards close to our chest, we still experience what we express. Even if we're not feeling particularly genuine in what we're expressing it still affects us at that moment, beyond the presentational self.
The fact that (1) what we choose to express nonetheless still affects us, and (2) serves to be the means that we express ourselves to others, seems to show that 'the social face' we put out is, at least in part, our "true selves."
Expression is one of the few things we can attempt to control - but even that is thoroughly effected by who we are, and we're affected by how we do it. Who ho we express ourselves to be is part of our true self - performing is being.
I apologize for any and all misuse or reversal of the correct usage of 'affect' and 'effect' in the above. Here's MJ singing Man in the Mirror as recompense.