Final answer:
The effect/bias is response bias, where subjects change their answers due to certain cues or influences from the researcher or the research environment.
Step-by-step explanation:
The effect/bias that the secondary researcher noticed is called response bias.
Response bias occurs when subjects change their answers due to certain cues or influences from the researcher or the research environment. In this case, the subjects changed their answers when the lead researcher raised his eyebrows upon hearing their first response.
For example, in the Hawthorne effect, which is a type of response bias, people change their behavior when they know they are being observed as part of a study. This effect can lead to inaccurate or biased responses.