Both infrequent and habitual use of _____ may cause users to experience distortions in visual, auditory, or any other mode of perception

"Runner's High" occurs when prolonged, intense athletic activity causes the release of _______, in the brain's natural painkiller.

a) Adenosine b) Glutamate c) norepinephrine d) endorphins

William Perry suggests that over the course of their college careers, students' thinking progresses through ______ levels of complexity

Fill in the blank with correct word