Attitudes and Conflict in the Workplace
Pessimists may be more likely to see the cloud rather than the silver lining. Our perceptions tend to be situational as well; everyone, even the most optimistic of us, can be overcome by pessimism and regard people's motivations as negative.
When Sam was asked to do an important project instead of me, for instance, was it personal? Did my boss really want to punish me/make me mad, etc.?