Our brains aren’t wired to understand randomness

December 3, 2008

I’ve read a couple of very interesting articles about randomness and iPods that have put a doubt in my mind about the whole notion of the shuffle function and its “shuffle”-ness.

Here’s one. The following is an excerpt from the famous article on Newsweek

Just about everyone who has an iPod has wondered how random the iPod shuffle function really is. From the day I loaded up my first Pod, it was as if the little devil liked to play favorites. It had a particular fondness for Steely Dan, whose songs always seemed to pop up two or three times in the first hour of play. Other songs seemed to be exiled to a forgotten corner of the disk drive. Months after I bought “Wild Thing” from the iTunes store, I’m still waiting for my iPod to cue it up.

More specifically, when an iPod does a shuffle, it reorders the songs much the way a Vegas dealer shuffles a deck of cards, then plays them back in the new order. So if you keep listening for the week or so it takes to complete the list, you will hear everything, just once. But people generally listen only to the first few dozen songs. In theory, that sample should be evenly distributed among all the artists and albums in their collections. So why do you typically get three Wilco songs in an hour while Aretha Franklin waits in the wings forever?

I explained this phenomenon to Temple University prof John Allen Paulos, an expert in applying mathematical theory to everyday life. His conclusion: it’s entirely possible that nothing at all is amiss with the shuffle function. It’s quite common for random processes (like coin tosses) to get unlikely results here and there, like runs of six heads in a row. Over a very long time, it evens out, but it’s hard for us to envision that. “We often interpret and impose patterns on random processes,” he says, adding that this might be expected in the case of music, which evokes strong emotions. Paul Kocher, president of Cryptography Research, puts it another way: “Our brains aren’t wired to understand randomness.”