12) Bob and Stu think that ginger can increase intelligence. So they build a simple maze, and record the times of 6 lab rats running through. Over a period of 3 days they increase ginger intake on each day, and re-measure the maze times. Each rat is tested once each day. As incentive, the rats are deprived of food for 5 hours before each test, and tasty rat food is placed at the end of the maze each time. Bob and Stu find that running time decreases each day. They thus conclude that ginger increases intelligence. find the independent and dependent variable