Internet users can give web sites a thumbs up or thumbs down in less than the blink of an eye, a new study has found.

In just one-twentieth of a second - less than half the time it takes to blink - people make aesthetic judgments that influence the rest of their experience with an internet site.

The study was published in the latest issue of the Behaviour and Information Technology journal.

The author said the findings had powerful implications for the field of web site design. "It really is just a physiological response," Professor Gitte Lindgaard said. "So web designers have to make sure they're not offending users visually.

"If the first impression is negative, you'll probably drive people off."

Researchers discovered people could rate the v.....