What is a common feature of paranoia?

A common feature of paranoia is unfounded suspicion. This characteristic implies that an individual experiences persistent and irrational distrust of others, often believing that people are out to harm them or that there are hidden motives behind others' actions. This suspicion is not based on any solid evidence, making it a central element of paranoid thoughts and behaviors.

In the context of paranoia, the other options do not align with the defining traits of the condition. Excessive optimism is contrary to the negative outlook typically observed in paranoia, where individuals are more likely to interpret situations in a threatening manner. Extreme sociability also does not reflect paranoia, as individuals experiencing paranoid thoughts often withdraw from social interactions due to their mistrust. Increased self-confidence can be present in some psychological states, but in paranoia, the focus is more on feelings of threat and suspicion rather than self-assuredness. Thus, unfounded suspicion stands out as the primary feature in understanding paranoia.