What is the main effect of demand characteristics on participant behavior?

Demand characteristics refer to cues within an experimental setting that might inform participants about what the study is supposed to be about, possibly leading them to alter their behavior in response to perceived expectations. When participants become aware of the study's aim or hypotheses, they might attempt to act in a way that aligns with what they believe the researcher wants to see. This guessing can often skew the findings, as participants may intentionally try to conform to perceived expectations or, conversely, act in ways they think will contradict those expectations.

In this context, recognizing that participants might guess the study’s aim helps us understand the challenges researchers face in designing studies that yield genuine responses rather than responses influenced by the participants' interpretations of the study's purpose. This also highlights the importance of keeping study objectives clear and ensuring that participants are unaware of them to maintain the integrity of the data collected.

The other options do not accurately represent the primary impact of demand characteristics. While they may seem relevant, they do not address how participants' awareness of the study's aims affects their behavior in a direct way.