In the experiment a group of people are shown two cards. The first card has a single line on it. The second card has three lines on it labelled A,B,C one of which clearly matches the length of the line on the other card (and the other two clearly don't). Only one person in the group is the actual subject and is unaware that the other members of the group are part of the experiment. The experiment measures how likely the subject is to conform to the answer given by everyone else when that answer is clearly the wrong one. The answer is "quite a lot". But that's not what I learned. What I learned about is a variation on that experiment. One where Solomon Asch measured how the effect varied depending on how many other people's answers matched, or didn't match, the subject's answer. You can read about this variation (and some others) here. This is the punchline:
The presence of a [single] supporting partner depleted the majority of much of its power. Its pressure on the dissenting individual was reduced to one fourth: that is, subjects answered incorrectly only one fourth as often as under the pressure of a unanimous majority.
Isn't that a great example of the power of setting an example. Of how change happens one person at a time. Of courage. Of how important it is that people feel safe. People are always more impressed by the power of our example than by the example of our power.