From Eric Barker’s blog:
Conventional wisdom suggests that by “sleeping on it,” we clear our minds and relieve ourselves of the immediacy (and accompanying stress) of making a decision. Sleep also helps organize our memories, process the information of the day, and solve problems. Such wisdom also suggests that conscious deliberation helps decision making in general. But new research (Dijksterhuis et al., 2009) suggests something else might also be at work — our unconscious.
Previous research suggests that sometimes the more consciously we think about a decision, the worse the decision made. Sometimes what’s needed is a period of unconscious thought — equivalent to “sleeping on it” according to the researchers — in order to make better decisions. Here’s how they study this phenomenon:
“[… In a] typical experiment demonstrating this effect, participants choose between a few objects (e.g., apartments), each described by multiple aspects. The objects differ in desirability, and after reading the descriptions, participants are asked to make their choice following an additional period of conscious thought or unconscious thought. In the original experiments, unconscious thinkers made better decisions than conscious thinkers when the decisions were complex.”
The researchers suggest that unconscious thought, contrary to the way many of us think about it, is an active, goal-directed thought process. The primary difference is that in unconscious thought, the usual biases that are a part of our conscious thinking are absent. In unconscious thought, we weigh the importance of the components that make up our decision more equally, leaving our preconceptions at the door of consciousness.