The Netflix Prize will soon be over: it sounds as if the team “Bellkor Pragmatic Chaos” will be granted the million dollar prize, awarded for improving Netflix’s own algorithm by more than 10 percent. As a heavy Netflix user, I certainly appreciate the design of the website, which does a masterful job of framing my DVD options. Although Netflix has hundreds of thousands of DVD’s, I rarely feel overwhelmed by the abundance, since I’m constantly being bombarded with suggestions. Did I just add Season 6 of the Sopranos to my queue? Perhaps I should try the Shield, since I also liked The Wire? Did I enjoy The Class? Then maybe it’s time to re-watch Chinatown? In other words, my choices are intelligently framed – the constraints make me feel free, or at least less burdened by the problem of excessive choice.
That said, I find the actual Netflix Cinematch algorithm – the software tries to predict how I’ll feel about movies based on my past ratings – to be utterly useless. And it’s not just for quirky movies like Napoleon Dynamite, or Syndecdoche, New York, or everything by Wes Anderson. Instead, I find that those suggested stars rarely capture my actual preferences. Of course, I’m sure the fault is mostly mine – I rarely take the time to review my selections, and when I do I’m pretty careless. I haven’t devoted nearly enough time to figuring out the difference between four stars and five stars, or found a way to merge my ratings with those of my wife. (I enjoyed Synecdoche; she thought it was garbled and pretentious.)
But I think there’s a deeper problem with these newfangled preference algorithms, and it has nothing to do with the details of their programming code. Instead, I think they’re making a fundamental psychological mistake: all of these algorithms assume that our preferences are stable and consistent, but that’s clearly not the case. In other words, Netflix assumes that if I like Napoleon Dynamite on Saturday night then I’ll also enjoy it on Sunday afternoon. It assumes that I’ll find Pineapple Express funny when I’m watching it with a bunch of stoned friends and when I’m watching it sober and alone, on a weekday evening. It also assumes that I’ll want to watch the same list of movies regardless of when I’ll be watching them.
I think my own Netflix habits demonstrate the fallacy of such assumptions. For instance, I’m constantly adding all sorts of highbrow fare to my queue. Why? Because I like to think of myself as someone who wants to watch the complete Criterion collection, from Bergman to De Sica. I know I should watch those classic Chaplin movies, so I add them to the list too. And then you know what happens? Those pretentious red envelopes sit on top of my DVD player for weeks at a time, while I enjoy all sorts of middlebrow crap. The moral is that I assume my future self has more refined taste than my actual self – there is a jarring inconsistency between my stated preferences and my actual desires.
There’s a perfectly good neurological explanation for this phenomenon, which is that decisions involving the distant future tend to activate circuits in the prefrontal areas. The end result is that we think more deliberately and dispassionately, and choose movies that seem intelligent, classy, etc., even if they involve subtitles and tedious plots. Of course, when it comes to choosing which of our Netflix options we actually want to watch tonight, the decision is shifted to a different brain system, and seems to activate a more emotional and impulsive set of cortical areas. This leads, of course, to a different set of preferences: I’m less interested in early Fellini and more likely to opt for Superbad. I want some laughs and pleasure, and I want them right now.
Needless to say, this sort of temporal inconsistency is only one of the many different ways our preferences prove inconsistent. Where we watch the movie, who we’re watching it with, and the mood we bring to the couch are often just as important as the actual stuff on the screen. So this is why I don’t think a new and improved Netflix algorithm will suddenly solve all my movie dilemmas. The software, you see, is founded upon a simple mistake: it assumes that I know what I like, and that I always like what I like, but that’s rarely the case.