The benefit of optical illusions

The Bad Astronomer (Phil Plait) likes to share optical illusions and explain how they work. The moral he draws is that our mere meat bodies can't tell us what's going on.

But I've been thinking about it, and actually, I think that the mechanisms behind optical illusions are exactly why we can tell, to a large degree and usually as well as we need to. That thing where the mind extrapolates from  little bits of information to build a whole world of stuff beyond what we strictlyh see and hear and smell and touch and taste: that's how come we know anything. You see a blur and a blob and a couple of moving lines and you think "Here comes Yolanda, and she's kinda pissed, so I bet her bus was late again." You cast a swift glance at a sign and you see a smear of a green rectangle at a height somewhat above your head and some fuzzy shapes and dots and lines and you think "That was Washington Street, I'm turning right on the next block." There is no way at that distance and with that brief a glance that you actually read "Washington Street" off that street sign. If you had to have accurate inputs, you wouldn't even have been sure that was a street sign with the amount of information you picked up.

Yesterday's translation exercise was a good example too. Google translate didn't know what to do with words that didn't comform to the entries in their dictionaries, even with google's famous fuzzy logic. It couldn't figure out that koníčka vraného meant "crow-black pony," and it couldn't figure out that šabla nabrúšná meant "sharpened saber," and it couldn't figure out that na štyry noženky kutého meant "trotting on four feet." There were lots of reasons. kůň "horse" is in the online dictionary, but if you look for "pony" you will get ponik, not koníčky, though all songs in my children's song book use the latter. And since the online dictionaries (I also used a few others besides Google) could not handle koníčka, they also could not parse the next word, which is the adjectival form of the noun vrana "crow." Another thing that threw the dictionaries was dyž instead of když for "where." Since all the verbunky songs I looked at on the website had it, I assume it is a Moravian dialect sort of thing. Google rendered it as "hen," which was really confusing, because it is nothing like kuře. Only after I figured out that it must be "when" did I realize that Google had gotten it right and was dropping the "w" in a show of misguided solidarity with the sensibility of the text.

Google and I forget the name of the other text translator threw up their hands at noženky. For a moment I thought the verse was about penknives but browsing through the various dictionaries showed me that "shanks" was a reasonable interpretation, and then when I found the word behing used later in company with the word for horseshoes, I figured it out. And šabla is a variant of šavle.


So, I had to know things already: recognize tiny similarities, understand how loinguistic variation works, and relentlessly fill in the blanks. I could not have done it without the sort of perceptive system that also falls prey to optical illusions.