If I tell you: don't think about an elephant! What are you thinking about? An elephant, right? 
If we put it in the context of children: if we tell them "don't do this or that" then their brain will hear "do this, do that".
The human brain is not made to understand negation.
What if we changed our way of speaking to only use the positive form?
It is a rather difficult exercise for our brain since we’ve been learning what is forbidden from a young age instead of what is allowed.
In early childhood jargon, the "crucial" period of 18 months old to 2 years old is often referred to as the "early teenage years" or the "no" period, as a lot of changes happen at this time regarding development, just like during the teenage years.
Children aged 18 months to 2 yo will tend to say no to everything, even things they want. That can be either because they try to imitate adults, or because they want to differentiate themselves from the person they are attached to (parents, grandparents, caregivers…). Children will try to be more independent from the adults and gain autonomy, they will try to assert their own choices.
And you, as parents, as caregivers, how did you live/ are you living this period? What if this little tip changed our perception of things and could avoid many conflicts / frustrations?
