It's often said that first impressions count, but who would have thought this would also be true on the web?

The columnist's best friend "a recent study" has proved that most of us decide whether a website is cool or not within a 20th of a second of seeing it!

I thought it was just me. Being in the business of making websites, I've got into the bad habit of condemning sites before I've even used them and, in some cases, before they have even finished loading. It seems I'm not the only impatient one.

Despite lending my voice to the 'usability is more important than graphic design' posse, the study has made me realise that I too am judging websites on their looks.

But the good - or indeed bad - news, depending on which side of that debate you're on, is that the study indicates that once we have decided we like a site, we are likely to stick with it, even if it turns out to be rubbish.

Even if the site actually confuses and frustrates us we tend to keep using it. It apparently takes a lot for us to admit we were wrong and remove it from our favourites list.

It seems that when we fall in love with a site we become blind to its faults and that users will always forgive beauty. Before I get too Mills & Boon on you, let me point out there is a scientific explanation for this. Usability experts are calling it the "Halo Effect".

Surfers believe that if a website looks great, then its content and usability will be of equal quality, and with good reason. If a company has coughed up money for professional web designers they have probably spend a few bob on making the site work properly and filled it with compelling content.

Sadly this is often not true. Many corporate sites are a vision of loveliness but contain no valuable information. Many are often just an exercise in corporate vanity and their owners have clearly forgotten to ask themselves the important question "what is this web site going to do for its visitors?"

But what can users really know about a site in 20 milliseconds - in quite literally the blink of an eye?

They can't be reading many of the words and certainly not the long introductory "Welcome" text most site content managers seem to favour.

However, an image can be sent to the brain in this short time and its message understood. That's why it's important to re-enforce whatever your home page proposition is with powerful images. If you sell life rafts, show a picture of a drowning man.

The study essentially shows that web users are impatient, quick to judge and seldom change their minds - or is that just the whole human race?

More importantly, it has made me admit that good website design is almost as important as good usability.

* Chris is managing director of Internet consultancy. This and other unedited articles can be found at E-mail