Do you really think people surfing the net spend any time at all at websites that challenge their preconceived notions or rather rather they

I prefer websites like this one, or the old Ask, where we can all challenge each other's ideas in a friendly way and learn from the experience. 

I spent 5 or 6 years on Ask before it was closed and enjoyed many discussions with people who had different ideas. The trick is to discuss those differences without waving a big flag that says, "I'm right and you're an idiot." 

Aye, agreed. A few of my questions end with "You decide". I value freewill.

It will be mostly the latter If you have opinion sites in mind. Lot of people don't really engage, or ask in a non-biased way.

I think we all tend to prefer sites that confirm our preconcieved notions. Is is kid of a self-reinforcing trap though, so I visit other places too.

depends on the person, everyone is different

There was a programme on the radio examining this very question recently, in the wake of all these silly clichés about "false news", "fake news" and such-like - lies basically.

It pointed out the self-reinforcement mechanism many may not even consider when in saying they receive their news of the world around them via social-media sites, they are doing so from circles that generally agree on each topic, and do not analyse what they read and re-transmit, still less try to verify the information.

You can assess the editorial bias of a newspaper or commercial broadcaster fairly easily. You cannot always do so with on-line "news" unless it is directly from such a publisher.

Even innocuous material like photo-galleries of non-contentious scenes, offered by ISP home-pages, admittedly sometimes with puerile headlines "most scary", can be wildly inaccurate. I found that with one showing assorted undersea scenes, mainly ship-wrecks. I took it at face value since I had no reason to doubt the veracity of the captions despite the stupidly childish wording at times. Then I saw another, and immediately recognised one photograph from the first - but the editor had moved the ship-wreck from the Egyptian coast to NE American waters! 

Perhaps the main and most worrying message is that far from being an international blessing, the Internet, or rather its use by social-media web-site owners and users, could become a serious threat to democracy itself.