Which type of observational study is most likely to be affected by demand characteristics?

The type of observational study most likely to be affected by demand characteristics is controlled observation. This is because controlled observations typically take place in settings where the researchers have some level of influence or manipulation over the environment, often involving a more artificial or structured setting. Participants may become aware that they are being observed and may alter their behavior to conform to the perceived expectations of the researchers.

Since controlled observations often include a clear set of conditions or tasks that participants are aware of, there is a heightened chance that they might pick up on cues from the researchers or the experimental setup, leading to demand characteristics. This can compromise the validity of the results, as any behavioral changes could stem from participants trying to fit the perceived expectations rather than their natural behaviors.

In contrast, other forms of observation—such as covert observation, where participants are unaware they are being observed, and naturalistic observation, which occurs in a natural setting—tend to mitigate the impacts of demand characteristics since participants are less likely to modify their behavior in response to observation. Non-direct observation, similar to covert and naturalistic approaches, also aims to minimize participant awareness and influence.