Which of the following is true regarding biases and research design?
A) The placebo effect is an experimenter bias where participants exhibit a response to a treatment that has no therapeutic effect.
B) In order to control for placebo effects, experimenters often give a portion of the control group an experimental treatment.
C) The practice effect is a confounding variable that cannot be controlled for through group assignment.
D) A blind experiment is performed when neither the experimenter nor participants know the group assignments.
Answer: C