“…Even the most conscientious confederates are at risk of inadvertently shaping participants' behavior by giving verbal backchannels or nonverbal cues such as facial expressions, body posture, tone of voice, pauses, or eye gaze patterns. Research has shown that these types of cues from an experimenter or examiner can influence people to do better on IQ tests (Congdon & Schober, 2002), inspire children to excel in their schoolwork (Rosenthal & Jacobson, 1968, lead infants to discard principles of object permanence (Topál, Gergely, Miklósi, Erdöhegyi, & Csibra, 2008), and even cause horses to behave as if they can read and do math (Pfungst, 1907).…”