Bayesian Recognition

We don’t meet often, but every time we talk, she reminds me that I had failed to recognize her the first time we had met after graduating together from school. Yes, I could claim in my defence that I was seeing her for the first time in over six years. While that might be a valid excuse for most people, it doesn’t apply to me, since I normally claim to have superior long-term memory. If I’ve seen you somewhere before, I ought to recognize you. The only times I don’t I’m pretending, since I don’t want to embarrass you (and myself) by recognizing you while you don’t recognize me (see this incident for an example of this).

The reason for my failure that cold Bangalore evening in December 2006 was that my Bayesian system had failed me. Let me explain, in the process giving you an insight into my Bayesian system which I use to recognize you when I meet you.

About a month or two back, I was at a friend’s wedding, which is where I hit upon this term “Bayesian recognition” to explain this phenomenon  (which I’ve been practicing for ages). Now, this friend whose wedding I was attending was one year my junior at two different schools. As you might expect at an event where you and the host share more than one social network, there were a lot of familiar faces. Some people I knew fairly well, and could easily recognize. But the others had to go through a “Bayesian search”.

So when I saw someone who was one of three people I know – let’s say X, Y and Z. In order to determine which of these this person is, I would ask myself two questions – firstly, what were the prior odds that the person I saw could be each of X, Y or Z. Secondly, what were the odds of each of X, Y and Z being there at that event. Note that the latter is important. For example, if someone at the event looks like you and I know (for example) that you are currently in another country, despite the strong resemblance I can discount the possibility that that person is you, and go ahead with my search.

Note that this differs from “frequentist recognition”, where I only look at the person’s face and try and understand who he/she most resembles, without any thought to the odds that that person is there. Frequentist recognition can lead to a large number of false positives, and after a few rounds of embarrassment, you start giving up on recognizing, and many a possible reunion thus gets missed. Bayesian recognition, on the other hand, restricts your field of search (to the people who you give good odds of being there), prevents you from being distracted and increases your chances of making a good recognition.

So why did Bayesian recognition fail me when I met this former classmate back in 2006? The problem was her company. She had come for this Deep Purple concert with another friend of mine, who was my classmate in another school (and who I had been in touch with, and so easily recognized). I had no clue that these two were friends (it turned out they didn’t know each other that well – they had come there with a common friend). So when this girl (the one I didn’t recognize) popped up with “Hey SK! Do you remember me?” I assumed that she was someone I knew from the same school as the other girl I was meeting, and that wrongly restricted my search space. And so my mind was trying to map her to my friends from school 1, while she happened to be a friend from school 2. And my search returned a blank, and my legendary long-term memory skills were embarrassed.

I must mention here, though, that this is possibly the only time that my Bayesian recognition model has acted up, and refused to recognize someone I know. There have been 2-3 false positives, but this has been the only negative. And when you consider the sample size to be all the people I have recognized in different places, this is small indeed.

Oh, and after failing to recognize her then, I’ve kept in touch with this friend.

Towards liberalism

I was raised in a fairly conservative family; my father’s atheism not preventing him from being socially conservative. Until I went to college, I never blew candles for my birthday, for they were deemed to be “against Indian culture” at home. I went to RSS Shakhas, my seniors at RSS stuck BJP posters on my door, and except for the 1989 Assembly elections when BJP didn’t put up a candidate in Kanakapura, my parents always voted for that party.

My wife comes from a different kind of family. They are religious but can be described as being more “secular” (her name (Priyanka) might suggest to you their political leanings). So she grew up doing poojas and keeping vratas on all sorts of random Hindu festivals, but also blowing candles on her birthday and calling up “Santa” and getting Christmas presents also. Yeah, you look for compatibility on several axes when you’re searching for a long-term gene-propagating partner, but political leanings are usually low down on that compatibility list.

Last year, I totally and completely failed to appreciate her celebration of Christmas, instead treating it as yet another random holiday, before and after which nobody did anything at work. I failed to give her any gifts, or organize any “christmas events” for her. Yeah, the in-laws came over, we had set up this little crib based on dolls we’d purchased in Sri Lanka on our honeymoon and all that (unfortunately we misplaced that set, else we’d’ve displayed it as part of Dasara too, this year), but I must admit I’d failed to “celebrate” the festival. And in my defence, it was never a festival that I had celebrated, so “forgot” was actually a valid excuse.

So this year we decided to have a Christmas party at home. Basically called a few friends over, most of whom responded with astonishment (thanks to my RSS legacy), but were kind enough to land up. And once again we searched hard and found that “crib set” and set it up. And started playing Christmas carols, until I got bored and switched the music to Black Sabbath, which nobody really minded. Much alcohol was consumed (especially wine, given the Christmas spirit), plum cake was had and Chinese food ordered in.

In the intervening years I’ve found myself becoming more and more socially liberal. It probably started when I moved to IIMB; I think that was the time I stopped being judgmental of people based on their backgrounds, and stuff. That was the time when I started respecting individual rights, and those leanings got stronger as I slowly opened up, joined a libertarian-leaning mailing list, and realized that this was actually what I (as a person, irrespective of my background) was about.

On a foreign vacation earlier this year, thanks in part both to the lack of interesting vegetarian options and the availability of fairly succulent-looking meat, I stopped being vegetarian. A few months after that I participated in a “Ramzan meat walk” (though I didn’t consume much meat during the walk, since a lot of it was ‘hardcore’). I find it silly now that I’d actually joined a group of hostel-mates that campaigned for a “vegetarian table” at the hostel mess because the non-veg food “looked too gross”. But when someone starts singing “Silent Night”, I only remember that variation that a chaddi dost and I had come up which changes the song’s lyrics in a way that it ends with “and two souls become three”.

Given a chance, if I were to register as a voter and there were elections tomorrow, I might still vote for the BJP, following family tradition, but that would be more in line with economic thought and lack of options rather than my conservative background. I oppose the forced 11pm shutdown of Bangalore pubs, but don’t care about it enough to join protests on that front. If the government subsidizes Haj and Kailas Mansarovar Yatras, I demand that I get funding to attend the Pastafarian conference in Texas. And I still intend to open my autobiography (whenever I write it) with the lines “As Babri Masjid came crashing down, I celebrated. It was my tenth birthday and we had a party at home … “.