One example is the entry zone at the front of the store - you'd think that's a prime location for signage, deals, brochures, etc. But when you're headed through the door into the store you see almost nothing and stop for almost nothing, and then (in America) you tend to drift to the right and then you're 'in' the store. If you put a store directory just inside the door, nobody uses it. Move it back a bit so you can find it once you're into the store and suddenly it's heavily utilized. He has hard observational data for all these, so they're compelling in addition to being fascinating.
And of course all the bad examples are great fun to read (seniors crawling along floors trying to read labels on badly shelved medicine), as are the descriptions of how different groups shop (male vs female, old vs young, parents vs. single, etc.) The whole book is pretty much a commercial for Underhill's company, but it's still informative and fun reading.
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