Final answer:
Zev's increased engagement and contribution within his team is most likely due to social facilitation and the Hawthorne effect, where the presence of others enhances individual performance, especially when the individual's efforts are noticeable and valued.
Step-by-step explanation:
The most likely cause of the social facilitation effect experienced by Zev is his exposure to a group environment that is engaging and supportive. In the presence of top performers like DeAnne and Ajoy, who are outgoing and well-liked, Zev feels motivated to contribute more actively. This behavior aligns with Zajonc's theory of social facilitation, which suggests that the presence of others can enhance an individual's performance on tasks in certain conditions. Additionally, being watched or evaluated by others, such as a supervisor, can lead to increased arousal levels and better performance, which is related to the Hawthorne effect. Importantly, this social facilitation effect seems to encourage Zev's investment in the team's goals and pushes him to take more initiative than he usually would in solitary circumstances.
It is also significant to note that the opposite effect, known as social loafing, often occurs when individual performances cannot be clearly evaluated, leading people to exert less effort. However, this is not the case for Zev, as he is likely feeling the individual pressure and thus becomes more engaged to secure the team's success on complex and challenging projects.