The second two UX elements that Graham points out are fundamentally the same idea – using the hover function to support effective browsing. He notes that on Lilly Pulitzer (which sells women’s apparel), when you hover over a product photo (such as a model wearing a Lilly Pulitzer dress) on a search results page or on a category page it shows you the rear view. On Land’s End, you can easily see an item in a variety of colors. Underneath each product photo there is a palette of colors that the item is available in. When you click on one of them, the item photo changes to that color without reloading the page.
For a wide variety of shopping use cases, seeing the rear view of an item and seeing the item in different colors are both very important. Using the hover control makes it easier and faster. How many times have you looked at a browsing function, estimated how long it would take for the page to load, multiplied this by the number of times you would have to use it while browsing the variety of products you want to consider, and then decided not to bother? To use this function, you would either have to invest a lot more time than you planned or you would have to consider just a few items. Not worth it.
I think the logic behind this is pretty generalizable. Any voluntary experience is a constant effort/benefit evaluation. How much physical and mental effort will it be and what will I get out of it? So any UX element has to be a net positive on this equation to be used and valued. Changing to a hover function from a page load reduces the time and the frustration levels for the same benefit (additional views of the item). There are some users on one extreme who would have used either version because they value the additional views very highly. There are some users on the other extreme who would not bother with either version because they don’t value the additional views much at all. But for those in the middle, we can add to their shopping experience and increase sales and satisfaction.
The vendor would have to judge the number of users in this middle category given its demographics and product category and compare that to the programming cost of the hover function. If you have decent data on these, it is a clear decision.
We can complicate this by also throwing in a variable like the time it takes for the hover effect to kick in. If it is too long, the user may never realize that the function exists. If they click and get taken to a detailed product page from the gallery page, then it defeats the purpose. But this is a subject for another post.