An experimenter was interested in seeing the effects of marijuana on studentâs heart rate. The experimenter randomly selected 100 students from SUCO campus and ran double-blind experiment. 50 of the students received .5 g of marijuana, and the other 50 received a placebo. The 50 students who received the placebo were separated and put in a room with dark walls, while the other group remained outside on the grass. The experimenter then asked the students to rate their heart rate on a 1-7 Likert scale. 7 meaning their heart rate is at its highest. He also performed a physiological test on the students to test their heart rate.
What could be considered extraneous in this experiment?