Additional variables - may often add nuance or an external explanation for a relationship. – is a variable that explains how two variables are related in different ways for different people or different situations. – explains why two variables may be related based an explanation that is internal.

Not all members of the radio audience of orson welles' war of the worlds broadcast panicked immediately. indeed, some didn't panic until they looked out of the window and saw empty streets; others didn't panic until they saw streets full of traffic. it was after checking out the situation that these citizens decided that the martians had indeed invaded earth. this example illustrates that contagion can result when people look to others for the interpretation of ambiguous situations . can result when cultural norms reinforce people's most likely responses. occurs primarily because humans are by nature irrational creatures. is especially likely when people are motivated to make independent decisions.