Ziggy Lynne Has Trained Her Dog, Ziggy, to Ring a Bell

Multiple Choice

Ziggy
Lynne has trained her dog, Ziggy, to ring a bell when he needs to go outside to urinate. First, she hung a bell from the doorknob. Every time she took Ziggy outside to urinate, she would ring the bell as she opened the door. If Ziggy bumped into the bell even by accident, she would praise him and take him outside (and he would get a treat each time he eliminated outdoors) . If Ziggy urinated indoors, Lynne would ignore him and clean up the mess very quickly. Ziggy learned that going outside to urinate led to treats and praise but urinating indoors led to no attention at all. Ziggy began to intentionally hit the bell with his paw when he needed to go outside. Once this began to happen, Lynne no longer opened the door for Ziggy when he simply bumped into the bell. Also, as the behaviour became more predictable, Lynne no longer provided treats every time Ziggy urinated outdoors. She only provided a treat for urinating outside approximately once per week. There was one major downfall to this training plan. Ziggy came to associate the sound of the bell with urination a little too strongly, so that he ended up wanting to go outside whenever the phone rang!
-Lynne provided a treat each time Ziggy went outside.What was the treat called,from a conditioning perspective

A)  conditional stimulus 
B)  positive reinforcer 
C)  negative reinforcer 
D)  unconditional stimulus