"I can't help it, it just comes out"

The shout can feel like something that happens to you. One moment you're asking about shoes, the next you're shouting, and there was no decision in between. On that view, the only cure would be a different temperament, and you haven't got one.

I'd question the "no decision" part, and I'd do it with the evidence you already have.

You don't shout at everyone. You didn't shout at the shop assistant who got your order wrong last week, or at your friend's child who was being just as difficult on Sunday, or at your manager. You were annoyed with all of them. The annoyance didn't turn into a shout, because the conditions were different. There were witnesses, or consequences, or a person you needed to keep on side. So the shout isn't a reflex that fires whenever you're annoyed. It fires when you're annoyed and there's nobody to stop you and the target can't retaliate. That's not a temperament. That's a set of conditions, and conditions can be changed.

The shout also has a run-up, and you can learn to see it. The NHS lists the body's signs of anger. A faster heartbeat, tense muscles, clenched fists, tightness in the chest, feeling hot. These arrive before the shout, usually somewhere around the second ask, and they're the last quiet moment. The ladder itself is a run-up you can watch. By the time you're using the full name, you're one rung from the top, and you know it, because you've climbed it a hundred times.

What follows is my suggestion. The thing to catch isn't the shout. By then it's out. The thing to catch is the third ask, the one with the edge in it. That's the moment you're still deciding, whether you feel it or not, and it's the moment to do something else. Go to the child instead of calling again. Or leave the room for thirty seconds. Or drop your voice to a near whisper, which is odd enough to get a child's attention and impossible to do while shouting. Chapter 19 sets these out.

There's also a plain fact about the pasta. Most shouts happen when two things need doing at once, and one of them is on fire. You can't deal with a child properly while a pan boils over, and so you deal with the child badly from across the room. Turn the hob off. The pasta can wait two minutes. The two minutes are what the quiet ask needs, and they're usually available if you take them.

"It just comes out" is how it feels. What's actually happening is a sequence with several points at which a different move is possible, made by a person who's decided not to shout at the boss. The same person can decide not to shout at the child. It's harder, because the child can't make you, and that's exactly why it matters more.