Subject selection - Keep It Simple Stupid

One choice too many
http://www.psychologytoday.com/articles/pto-20040116-000001.html

Variety is the spice of life, but too much spice can leave your tongue on fire. Americans have too many things to choose from, and the result is a society of stressed-out and unsatisfied customers.

The Tyranny of Choice
http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=0006AD38-D9FB-1055-973683414B7F0000

Logic suggests that having options allows people to select precisely what makes them happiest. But, as studies show, abundant choice often makes for misery

The Cost of More: Psychology of Choice in Interaction Design
http://www.syntagm.co.uk/design/articles/choice.htm

There has always been a difficult balance in the amount of choice offered to consumers. Too little choice means a store may be omitting services or products important to some users (and worse still, that a competitor might include). Too much choice adds complexity with increased potential for confusing or frustrating potential purchasers.