In Zajonc's theory, which of the following is commonly observed in the presence of others?

Zajonc's theory, particularly in the realm of social facilitation, posits that the presence of others can lead to an increase in arousal, which in turn can enhance the performance of an individual, especially in tasks that they are already skilled at. When someone is performing a task in front of an audience or peers, their arousal levels tend to rise. This heightened state can lead to better performance on well-practiced tasks because the individual is more energetic and focused.

However, the effect is nuanced; while increased arousal can lead to improved performance on tasks that are simple or well-learned, it can hinder performance on complex, unfamiliar tasks due to heightened anxiety or distraction. This theory underlines the concept that social presence can significantly influence individual performance dynamics.