The ratio of 3-to-1 is because a negative experience stands out more than a positive experience. Think of your relationships, do you remember the negatives easier than the positives?
I was thinking about how this applies to my life now as a parent. I have a feeling if my practicum advisor were to observe me on a normal day at home, my ratio would be embarassing! For much of the day I'm directing Caley and Amelia's behavior (neutral- "Come eat your lunch", "Get your blanket for bed", "Go to sleep") or flat out rebuking them when they do something wrong (negative- "Don't take your sister's toys"). And I know I'm not praising them three times more than negative or neutral interactions. Children remember the bad times far easier than the good times. I'm not saying it's not okay to tell your kids what to do in the normal course of the day, but I feel like I don't make a concerted effort to outnumber the neutral/negatives with positive interactions.
Lately I've been trying to be more conscious of noticing when Caley (usually) does something nice. She is so nice when I give her milk, she almost always says "Thank you." I try to say "Thanks for saying thanks Caley!" When they're just playing and I'm able to get some work done or just take a break, I have been trying to remember to say thanks or "I like the way you two are playing." This seems silly that I should even need to make a concerted effort to recognize the little things they do, but it's the truth. Many of the frustrations I may have with my kids and every day life are because I'm sinful, lazy and selfish. I want things to be my way or no way. I want my kids to read my mind and obey immediately. I am acting like a child. I can see God's hand in this. Lately I have had to go to Caley and ask for forgiveness for being too harsh or impatient. She sees my admission of sin and asking of forgiveness and hopefully will learn to do the same.
With God's grace, and thankfully he has an abundance of it, it won't always be this way. With grace, prayer and practice, praising my children will hopefully be more natural and the ratio will be three-to-zero.