to be suprised at or to be suprised by...

[mikko4]

OK then we wait... :}

[Clark]

OK then we wait... :}

Mikko4, I started a new thread where I asked the forum to help us on this problem.

[tzfujimino]

I'm not really sure whether or not I can be of any help...
but I visited British National Corpus to find a clue.(You might have done it already.) Here I'd like to provide you the link :

http://sara.natcorp.ox.ac.uk/cgi-bin...y=surprised+at
http://sara.natcorp.ox.ac.uk/cgi-bin...y=surprised+by

I'm also interested in this matter.

[David L.]

Getting back to your examples Mikko4:

e.g. I have a friend who has made it clear on a few occasions that he loves nature, all animals and then all of a sudden I see him killing an insect. I say
'I am suprised/shocked at your behaviour my friend.

You are shocked at his behaviour - it is totally the opposite of what you would have predicted/expected of him.

Adult psychopaths have a history of torturing and killing animals as children. So when I see a program on the Crime channel on TV about some psychopath who has murdered, and they give some biograpical background that includes killing animals, I am neither surprised by the information (I knew this to be a feature), nor am I shocked at it - it's exactly what I would have predicted of a psychopath.

but if my friend has a neutral attitude towards nature (never stated his opinion on it) then I should say I am suprised by your reaction.
This is a really good example, and explains why there is confusion over whether to use 'by' or 'at' - because it also depends on the speaker's perspective. So - I have known this friend for years, a nicer bloke you couldn't find, gentle etc. So - it took me by complete suprise - I was surprised by this whole new facet of his character I knew nothing about. It took me completely unawares. And - at the same time, I would still be shocked at his action, seeing this cruel streak in him, as it goes right against everything I would have predicted of him. I was shocked at his action, and surprised by the revelation of a side hitherto hidden from me.

What should I say here:
It's Monday. I am in the pub where I usually go on Mondays. The door opens and my boss, who I have never seen in this pub, comes in and sits next to me. I have always thought of him as of a rich man who doesn't go to such a places like pubs, bars and therefore consider him the least probable person to see in the pub on Monday evening.
I say 'I was suprised at seeing him in the pub. YES

but what say it wasn't my boss but my friend whom I had seen in the pub a few times, though not recently. I say: I was suprised by his arrival in the pub because it had been a long time since I saw him there last (time-omit).
YES - particularly if you thought he had moved house so this was no longer his local, or that you thought he was hanging out with a different crowd down at the Bull and Bush.