The strength of icons lies in recognition, not recollection, so your experiment doesn't prove anything. Essentially, I have no idea off the top of my head what the <arcane image processing tool> icon looks like in Photoshop, but put me in front of an open Photoshop and I'll recognize it in a split second.

A lot of this has to do with placement, yes, but I'm sure even without that, you can scan a mass of icons much more easily than a mass of text.