The Representativeness Heuristic

Base-rate neglect and English fluency

I often hear Indians speak in fluent English (with an American accent) and I assume that they must be really smart people. For some reason, that makes me feel insecure, but that’s another story.

Why do I think they must be smart? I imagine that really smart people are highly likely to speak fluent English. So, when I see people who speak fluent English, I think they must be really smart people.

Wrong answer! I just fell for the representativeness heuristic. This says that, to decide whether an object belongs to some class, we will just look at how similar it is to this class.

Specifically, I fell for base-rate neglect here. I failed to realize that although smart people may speak fluent English, there are a lot of non-smart people in the world and even if some small fraction speaks fluent English, that would swamp out the previous effect. To illustrate, assume that 1% of people are “really smart” according to me - so, around 1,000 in a population of 100,000.

Further, assume that 100% of all smart people speak fluent English (unlikely, and unfair to those from non-English backgrounds, but still) - so, around 1,000 smart and fluent speakers. Next, let’s say just 5% of “non-smart” people speak English fluently - maybe by paying attention to American movies and sitcoms, or by just talking a lot and trying to impress each other instead of having their nose in a book all the time. I’m caricaturing them unfairly, but that gives us 5,000 non-smart but fluent speakers. So, you have 1,000 smart, fluent speakers and 5,000 non-smart, fluent speakers - a total of 6,000 fluent speakers.

Now, given that you see someone speak fluently, how likely are they to be a smart person? Well, it’s 1,000 out of 6,000 - a chance of around 17% percent. It’s five times as likely that it’s a non-smart person. And remember, I assumed that all smart people speak fluent English, which is not the case. Plus, I only assumed that around 5% of non-smart people speak fluently, which is probably an underestimate, given how American influences are spreading in India, and how social norms are changing to reward sounding fluent in English.

So, the next time I see some fluent speaker and start feeling insecure, I need to remember to factor in the base rate of non-smart people. Phew.

Notes

Note that I don’t understand precisely when we will make this mistake. I need to study the original papers more to get that level of understanding.