This is a Question with Multiple semi-unrelated Levels..
The First level is, what is a "Good Person"? Sure there are plenty of people that appear as good, but when they are placed in a certain situation their true Nature Shows..
A simple example of this can be seen in observing others playing a Competitive Sport. With Witnesses as an Example, you might have 3 brothers that are known as being kind and sweet in the congregation, however once they get onto a Basketball Court these same brothers are throwing Dirty Elbow Shots, and they are trying their best to bridle their rage towards each other.. After observing this you have to ask.. "Did the Sport Change these Men?" OR "Did the Sport simply show who these men Truly are?" It is my view that The SPort removed the Fine Tuned Facade, and gave a Glimpse of the True Nature of these men.. Conclusion.. There are not too many "Good People" when it comes down to it.
The Second level is a bit more complicated - All Humans posess 4 Qualities which can compliment or oppose each another..
The Qualities are Love,Justice,Wisdom,Power.. all four of these qualities are regulated by two other qualities.. Pride & Humility.
We would think of a "Good Person" as someone that has a great deal of Love, however when this person is put into a situation where he has to decide between Love & Justice, humility is the Deciding Factor. If he is a Proud person, most likely he will take the route that favors his Perception of Justice, if he is a Humble person he will realize that he himself is also flawed, and for this reason he will take the route that Favors Love (Forgiveness).
The same applies when this "Good Person" faces a situation where he has to decide between Justice & Power.. If he is not Humble, he may choose to Display his power so as to teach any onlookers a lesson.
The Third Level involves Self Confidence and Insecurities -
In a Group Setting, an Insecure person subconsciessly places a great deal of Value upon being accepted Socially.. This leads him to make decesions based on the perceived consequences relating to his peers accepting him or rejecting him. The study mentioned in the Article is a Prime Example of this.. The Test subjects that were responsible for Increasing Voltage at the request of the Supervisor, did so because they were insecure and they feared dissapointing the Instructor.
This becomes even more powerful when you have a leader or instructor whom has mastered the Art of Rhetoric..He Promotes him self as someone who deserves respect and devotion / He convinces you that by following him, you will be accomplishing a worthy deed / He manipulates you to think that his Plan is Logical and thus Correct.
Humans are feable, and gullible.. If a Human does not have a STRONG belief system, coupled with True Humility he can be convinced by someone, or himself to do anything.