Thank you for the great follow-up!
I’m afraid I haven’t come across any studies that have examined this concept. Perhaps other readers have and can share? However it is frequently described in the popular literature and by teachers and others. Some Parents seem to be more and more reluctant to have their children experience any kind of distress or discomfort and protect them, helicopter etc. To be clear, I don’t think we should be creating challenges for our children, but rather helping them deal with the everyday challenges of the day. It doesn’t mean we tell them to ’toughen up’ but rather help them label the cause of their distress, name their feelings, and come up with ways to face it.