[simonask]

Where I am, I was taught that activating the turn signals means "I have made a decision to change lanes", so the appropriate reaction from surrounding traffic is to either safely accommodate that choice, or indicate using the horn and/or lights that the decision is unsafe and must be cancelled.

I'm in Scandinavia, and it feels like surrounding regions have similar conventions.

[moondowner]

That's the case in Europe in general, yes.