What is the name for this form of "influence"? I have found that people are often &quot;roused to action,&quot; activism and even zealotry by attributing either extreme of &quot;nobleness&quot; or &quot;despicability&quot; to their self or group identity.
I don't know if there is a name for this phenomena.  I'll give two examples to help pin this down.
Attribution of Despicability
For example, Fred is an evangelical who has an axe to grind with Catholicism.  Fred encounters an apathetic Catholic named Phil, who neither knows or cares anything about his alleged Catholic faith, and yet Fred proceeds to blast Phil verbally (under the appellation &quot;you Catholics&quot;) for how despicable and anti-biblical their beliefs are.
Phil becomes very unsettled and defensive from this encounter, and subsequently chooses not just to learn his faith - but to defend it as well. Ironically Phil grows into a zealot for his Catholic faith due to Fred's negative outburst.  It could be said that Phil has (subconsciously?) resolved to prove Fred wrong or perhaps to attain a form of revenge?
Attribution of Nobleness
Jake, a young man, is an athletic but wayward soul.  He encounters a decorated army veteran named Gabe who says &quot;I've been watching you for several days now lad, and I can tell you that in you is a greatness that is meant to be released.&quot;  The subsequent conversation inspires Jake to join the military and, indeed, Jake subsequently has a stellar military career that proves Gabe was right!
Wrapping Up
I realize that not every dynamic has a specific name in psychology, but it troubles me that the overall phenomena I'm outlining isn't represented in public dialogue, particularly when it comes to politics.  I believe the nation is becoming increasingly polarized and hostile because &quot;attribution of despicability&quot; is counter-productively generating the wrong kind of zealotry and thus ever-deepening unproductive contrasts.

&quot;You leftists just want to destroy democracy&quot;.  Well, the &quot;leftist&quot; did not have an opinion about democracy before the accusation, but due to the judgmental accusation...the leftist began to study and embrace arguments of why democracy is evil.
&quot;You rightists just want to subjugate minorities&quot;.  Well the &quot;rightest&quot; who had no particular sentiment before now adopts a passive-aggressive attitude about those who claim to support minorities and perhaps against minorities as well.

In short, both positive and negative accusation(s) have a catalytic or causal power.  Seen this way, in the case of negative accusations which we use to judge and condemn, the reality is that &quot;we have met the enemy, and it is ourselves.&quot;
I wouldn't be surprised if psychology has two names which treat both the &quot;attribution of nobleness&quot; and the &quot;attribution of despicability&quot; as two different things, even though I see them as flip-sides of the same coin.
Any ideas?
Update
Until I learn more about this, and understand it better, I'm going to call the overall phenomenon &quot;Manifest Testimony&quot;...intentionally echoing the phonetics of the otherwise unrelated &quot;Manifest Destiny.&quot;
I have some ideas about your first example. During my course of social psychology a learned about self/social categorization, two concepts that shape how individuals perceive groups. Here are some quick definitions.

Self categorization:


  the process of seeing oneself as a member of a social group (Smith, Mackie &amp; Claypool, 2014)


Social categorization:


  The perceptual classification of people, including the self, into categories (Forsyth, 2014).


According to self and social categorization people automatically view themselves as part of a group and others as part of a group also. I think Phil in your example still views himself as part of the group "catholics" (even though he does not know much about it) and Fred as part of the group "Evangelics". After that there are quite a view phenomenons that suggest people care about their beliefs and about their group status. One good example in this context is the ingroup-outgroup bias:


  The tendency to view the in-group, its members, and its products more positively than other groups, their members, and their products. Ingroup favoritism is more common than outgroup rejection (Forsyth, 2014).
  So, Phil might realize that he is part of the group "catholics" and subsequently becomes more defensive. 


Also it could be possible that Phil experiences some form of cognitive dissonance (an adverse psychological state that occurs when an individual simultaneously holds two conflicting cognitions (Forsyth, 2014)), because he claims he is part of the catholic group but is blatantly confronted that he barely knows anything about his group. This might lead to the attitude change you suggest, that he wants to learn more about catholicism. 

Of course this is more a description of how processes in groups can work and how people influence each other based on these processes. It is in no way a description of a scientifically backed up process/theory, although the terms used in my description are of course backed by science.

As for the second example, I personally believe there could be a lot of factors that lead to Jake's decision of joining the army. I think it would be hard to pin it down on the few words of the army veteran.

However, I am not an expert on social psychology. So I hope this information helps understanding social processes but it might not be a complete and conclusive answer. If you are interested in social psychology and group dynamics then I recommend to check out Forsyth's book Group dynamics. It explains concepts wihtin the field very well and uses informative examples. Hope this helps in some way.

References

Forsyth, D.R. (2014). Group dynamics (6th ed.). Belmont, CA: Cengage Learning. ISBN- 13 9781133956532

Smith, E.R., Mackie, D.M., &amp; Claypool, H.M. (2014). Social Psychology (4th ed.). New York, NY: Psychology Press. ISBN 978-1-84872-894-3