This is based on human psychology. 

Link to buy my ebook: Leveraging the power of subconscious mind to make your child start speaking: https://hub.parentingwithbhumika.in/courses/make-your-toddler-start-communicating

To Register for my 3 days workshop on how to enhance communication skills of your toddler: https://hub.parentingwithbhumika.in/f/5-days-speech-delay-program-copy