In the first study, participants rated Chinese ideograms for attractiveness. In a following study, participants were asked to judge paintings that were widely considered high- or low-quality. Subsequent groups of participants rated jellybeans and apartments. In all the studies, some participants were encouraged to deliberate and others to go with their gut.

The more complex the decision, the less useful deliberation became. For example, when participants rated apartments on just three primary characteristics (location, price, and size) deliberation proved useful. But when the decision became more complex (with nine characteristics) the participants who deliberated made worse decisions.

I know the feeling. Bad things happened when decisions were made that went against my gut feeling.

Gee - my whole education has been wasted.