When the researcher's expectations influence participant's behavior and/or the researcher's interpretation of the experimental results, it is called

Experimenter Bias

Explanation:

Experimenter bias is a phenomenon in research where the researcher influences the behavior of participants and/or the researcher's interpretation of the experimental results. This is because as humans it is almost impossible to be objective due to the feelings and emotions we have about certain thoughts and actions and as a result, these feelings and biases are mirrored into the research thereby reducing the accuracy of said research.

More often than not, this bias is unconscious which makes it even more deadly because it will be harder to detect by the researcher who will then be unable to take countermeasures to mitigate the effects.

answer; participants attitudes about gun control;

answer; incorporation;