I was tempted to say thank you for something today.
I didn't.
Why?
Because I was stepping beyond conventional etiquette.
Why?
On examination, I wanted to positively reinforce the person's behaviour.
What's the word for this?
Manipulation.
Stop it!
If the situation conventionally commands a 'thank you', say it.
If not, don't.
***
How can gratitude be shown instead? Silently pay it forward.