"We assumed that, given the task of finding an appropriate digital camera, people would whittle down the attributes such as price, megapixel count, and brand, and arrive at the few options best suited to them. If they had questions along the way, they could read helpful guides that would define terms, suggest comparison strategies, etc.
Again and again in our observations, that didn’t happen. People who knew little about digital cameras made no attempt to bone up. Instead they’d barrel through the taxonomy, usually beginning with a familiar brand, and get to a product page as quick as possible. It was only then, when looking at a specific item, and seeing what it’s basic specifications were, did they pause, sit back, and think, "Hmmm. This has 2 megapixels. I wonder how many I want?" Some would look for glossaries or guides, others would read reviews, and some just guessed by comparing the various products."
This poses similar design questions to how to best handle search engine visitors, who typically arrive at the most granular level on your site (both because most sites have more pages dedicated to individual products or entries than lists, and because you’ll have more specific keywords on those phrases). Most people who build web sites are thinking in terms of letting users drill down but I’m sure there’s a lot to be done the other way around, from the specific to the generic.