Question: A study examines if nicotine affects auditory performance. Young (18-27 years old), normal-hearing nonsmokers were randomly assigned to receive nicotine (Nicorette gum, 6mg) or placebo gum. Subjects performed four tasks to assess auditory performance (tone-in-noise detection, temporal gap detection, spectral ripple discrimination, and selective auditory attention) before and after treatment. Auditory performance differences between posttreatment nicotine and placebo conditions were measured. What is the independent variable? Need Assignment Help? Group of answer choices Auditory performance Subject group assignment (nicotine or placebo gum) Age group Hearing status