This blog has described what psychologists call the halo effect (See my post of April 13, 2007: “the tendency to make specific inferences on the basis of a general impression.”). Stylish clothes improve the assessments we make of the wearer’s unrelated attributes. Good looking people get the benefit of being thought more capable; a partner from an illustrious firm is unthinkingly presumed to be blessed with better legal ability.
The halo effect is one of many tricks our fast-reacting System 1 can play on us, as well described by Daniel Kahneman, Thinking, Fast and Slow (Farrar, Straus & Giroux 2011) at Chapter 7. If you know that your colleague graduated Yale Law School, that actually says little about her PowerPoint skills, despite the glow of the halo. System 1 jumps to conclusions and spreads its thumb-nail impressions promiscuously, whereas System 2 thinking can more deliberately seek multiple sources of assessment, such as having someone else who is unaware of the pedigree read a document written by the colleague (at 84-85).