After findings about the brain areas responsible for understanding sarcasm and irony earlier in the week, we now have new research into the development of cynicism.
In this research, children of ages 6, 8 and 10 were told a story with an ambiguous ending that was open to multiple interpretations. These endings directly reflected the character’s motivation. As expected, the ten-year-olds were most likely to ascribe a self-interested motivation to the central character, indicating a well-developed sense of cynicism.
What surprised researchers was that even the six-year-olds were more likely, on average, to interpret the character’s behaviour as self-interested. This suggests that the seeds of a cynical outlook are sown earlier than had previously been thought. 
Mills, C.M. & Keil, F.C. (2005). The development of cynicism. Psychological Science, 16, 385-390
