Why “sleeping on it” helps

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.


The best book I have ever read!

I can identify with Nassim Nicholas Taleb’s following excerpt in Fooled by Randomness on biases in our daily lives:

My favorite time is spent in bookstores, where I aimlessly move from book to book in an attempt to make a decision as to whether to invest the time in reading it. My buying is often made on impulse, based on superficial but suggestive clues. Frequently, I have nothing but a book jacket as an appendage to my decision making. Jackets often contain praise by someone, famous or not, or excerpts from a book review. Good praise by a famous and respected person or a well-known magazine would sway me into buying the book.

What is the problem? I tend to confuse a book review, which is supposed to be an assessment of the quality of the book, with the best book reviews, marred with the same survivorship biases. I mistake the distribution of the maximum of the variable with that of the variable itself. Publishers would never put on the jacket of the book anything but the best praise. Some authors go even a step beyond, taking a tepid or unfavorable book review and selecting words in it that appear to praise the book.

Time dilation

From Neurophilosophy:

When a man sits with a pretty girl for an hour,” said Albert Einstein, “it seems like a minute. But let him sit on a hot stove for a minute, and it’s longer than any hour.” Einstein was describing one of the most profound implications of his Theory of General Relativity – that the perception of time is subjective. This is something we all know from experience: time flies when we are enjoying ourselves, but seems to drag on when we are doing something tedious.

Read the full article here.

The Unfair Subway

More probability from Frederick Mosteller:

Marvin gets off work at random times between 3 and 5 P.M. His mother lives uptown, his girlfriend downtown. He takes the first subway that comes in either direction and eats dinner with the one he is first delivered to. His mother complains that he never comes to see her, but he says she has a 50-50 chance. He has had dinner with her twice in the last 20 working days. Explain.

The Monty Hall Paradox

For some reason, I’ve suddenly become crazy over randomness and probability. I’m only halfway through The Drunkard’s Walk but this will definitely be one of my favorite books.

Here’s the Monty Hall problem:

Suppose you’re on a game show, and you’re given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what’s behind the doors, opens another door, say No. 3, which has a goat. He then says to you, “Do you want to pick door No. 2?” Is it to your advantage to switch your choice?

Marilyn vos Savant, famous for being listed for years in the Guinness World Records Hall of Fame as the person with the world’s highest recorded IQ (228), published this question in her column in Parade Magazine in September 1990. The question does appear quite silly. After all, when one door is shown to be a loser (assuming that we prefer a car to a goat), the probability of either remaining choice – neither which is more likely than the other – becomes 1/2. So why would switching make any difference? But Marilyn said in her column that it is better to switch.

This resulted in plenty of controversy, attracting some 10,000 mails including almost a thousand from PhDs. Many readers seemed to feel let down. How could a person they trusted so much on such a broad range of issues be confused by such a simple question?

When I was first asked the question, I too thought there would be no way that switching could make a difference. But the truth is, switching does increase your chances of winning. Here’s the solution from Wikipedia:

Singapore’s casino has officially opened – and never has the study of randomness been more timely.

Randomly yours,


On philosophy

Bertrand Russell encapsulates perfectly the purpose of philosophy:

“Philosophy, though unable to tell us with certainty what is the true answer to the doubts which it raises, is able to suggest many possibilities which enlarge our thoughts and free them from the tyranny of custom. Thus, while diminishing our feeling of certainty as to what things are, it greatly increases our knowledge as to what they may be; it removes the somewhat arrogant dogmatism of those who have never travelled into the region of liberating doubt, and it keeps alive our sense of wonder by showing familar things in an unfamiliar aspect.”