Ah, we have an answer

I posted a little article about some research on how quickly people get an impression of a web page. It’s quick; literally in the blink of an eye.

We here’s some real science just reported from Johns Hopkins U about visual perception and how it takes place. Ties in nicely with the observation about impressions.

"Vision doesn’t happen in the eye," Connor said. "It happens at
multiple processing stages in the brain. […]

"Humans do a rough categorization of objects very quickly,"
Connor said. "For instance, in just a tenth of a second, we can
recognize whether something we see is an animal or not. Our results
show that this immediate, rough impression probably depends on
recognizing just one or more individual parts of what we see. Fine
discriminations – such as recognizing individual faces – take longer to
happen, and our study suggests that this delay depends upon emerging
signals for combinations of shape fragments. In a sense, the brain has
to construct an internal representation of an object from disparate
pieces."