Answer:
treadle stepping increased because it had a "satisfying effect
Step-by-step explanation:
In one of Thorndike's puzzle boxes, a door would fall open when a cat stepped on a treadle, thus allowing the cat to reach food outside the box. Eventually the cat would step on the treadle as soon as it was put into the box. Thorndike concluded that TREADLE STEPPING INCREASED BECAUSE IT HAD A "SATISFYING EFFECT.