The Power of Positive Reinforcement in Parenting

2 year old Arya keeps hitting her mom Sami. Despite saying "No" repeatedly, Sami was on the receiving end of Arya's tantrum. After trying gentle parenting for a while, she had to resort to the old ways. Slap! She hit Arya, sure that this will put an end to the fuss, and almost anticipated Arya's tears. But they did not come. Instead, Arya slapped her back, harder this time. Tears did roll, but from Sami's eyes. Where did Sami go wrong?