The attributions of blame are negatively correlated to similarities between the observer and the people involved in the mishap, i.e. more responsibility is attributed to the people involved who are dissimilar to the observer.
[2]: 112 Walster (1966) hypothesized that it can be frightening to believe that a misfortune could happen to anyone at random, and attributing responsibility to the person(s) involved helps to manage this emotional reaction.
Where Walster's work suggested increases in attributed responsibility, Shaver's concept of "defensive attribution" argued for minimization of assigned responsibility based on perceived similarities between the attributor and the person(s) involved.
Shaver was able to demonstrate this response by describing events to test subjects; varying the situations and people described to either match or be significantly different from the subjects: as similarity with witnesses increased, attributions of responsibility decreased.
[2] In 1981 Jerry Burger published a meta-analysis of 22 peer-reviewed studies on the defensive attribution hypothesis, in which he found strong evidence to support Shaver's hypothesized negative relationship between similarity and responsibility.