The tendency of researchers to subtly and inadvertently affect the behaviours of participants in a study, obscuring the true effect of the independent variable, is called

The researcher's tendency to subtly and unintentionally sway participants, masking the true effect of the independent variable, is the experimenter bias effect.

Unconscious cues from the researcher steer participants toward expected outcomes.

The placebo effect is change in participants from believing they received a treatment, not researcher influence.

The Hawthorne effect is change from knowing one is being observed, again a participant-side reaction.

Evaluation apprehension is participants' anxiety about being judged, not the researcher's swaying.

Double-blind designs are the standard safeguard against experimenter bias.