Monthly Archives: December 2015

GIGO

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A huge tenet of programming is GIGO: Garbage In/Garbage Out.

Years ago when I was practicing for a play (Night of January the 16th by Ayn Rand). I was the bailiff.  At one point in the play I’m handed a copy of a check that is evidence. I’m supposed to “read” what’s on the check. Of course since it’s a play, I have my lines memorized.

But during this dress rehearsal I’m given a piece of paper with actual writing on it. Unfortunately it was just some random writing. But my brain went into segfault and I stopped. Part of my brain wanted to read what’s on the piece of paper.  Part of my brain wanted to say my lines, but it could no longer remember them.

It was a perfect example of how easy it is to scramble the input for our brains.  In the actual performances we made sure the piece of paper was actually blank.

I was reminded of this the other night when Steve Harvey made his gaff on live television. I was curious how he could make such a mistake but I had my suspicions. And I was right.  The cue card apparently was VERY poorly designed and his visual input system (i.e. his eyes and brain) screwed up. Read here for more details. Bad input lead to bad output.

These are humorous examples, but in the software world, these can be very dangerous.

At one point during the shuttle program, they found an error where the arm thought it had rotated more than 360 degrees, a physical impossibility. This link has some details (though in my recollection the issue was not a rounding error but that the code went from 0-360 instead of 0-359 or 1-360).  Garbage in could have lead to potentially bad garbage out.

Much more recently however, here’s an example of intentional “garbage” in. This is part of the encryption software used on many firewalls. Your bank or other financial institution for example may be using this code.

Ironically true garbage, as in a purely random number, might be better. But here it seems someone poisoned the input with their specific number and then set it up to use the results in a dangerous manner. I say dangerous because the 3rd party using this code may not realize that they’re completely vulnerable to having all their data seen.  About the only thing worse than unencrypted data is data you think is encrypted but isn’t.  In the former, I’m probably going to pay far more attention to who has access.  I’ll add too that some of us suspect the NSA had a hand in this.

This is by the way I highly recommend folks don’t write their own encryption. Unless you’re an expert you’re liable to screw it up.

Moral: So be careful of your inputs, they definitely influence your outputs, both in code and in your brain.

Page 81

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One of the things that has always fascinated me is human memory; how we create them, what sticks, what doesn’t and how it evolves.

Many people think that human memories are rather static. The truth is that’s far from the truth.  As we saw in the 1990s is easy to form false memories and easy to conflate them.

One detail that is interesting is that human memories are a bit like DRAM in a computer.  In essence when we recall a memory, we have to basically read out the memory space and write it back.  One of the side effects is this can actually help strengthen memories.  However, it also means when it’s written back, other memories can be conflated with it and a new, slightly different memory is formed.

There’s two main ways of remember something that stand out to me as I write this.  Repetition and what I’ll call “sudden shock”.

Many things we need to repeat until we remember them.  An example is a child learning their times tables. There’s really not much context and really only rote repetition will cause these to sink in.

At the other end of the spectrum are the memories that are etched in our minds. “Where were you when Challenger blew up?”  “How did you first hear about 9/11?”  If you ask someone of the right age, they’ll know exactly when/where they were and probably recall vivid details.

If you ask them where they were on the 3rd shuttle mission, they’d probably have no clue.  The same is true if you ask them what they were doing on 9/9.

In between are more general memories. Memories of childhood that don’t necessarily have a specific timestamp or even importance.  I recall playing in some woods behind my house growing up, but there was nothing really significant about the time or place. I have no idea why I have that memory.

I mentioned above that memories can be modified or manipulated. There’s some work on treating PTSD this way; helping patients recall specific events under controlled circumstances and essentially rewriting the memory into something that doesn’t cause an attack. (Propanolol is one drug being experimented with to do this.)

Strangely there’s one memory of mine that persists that while not a real issue is sort of pointless and annoying to me.  It’s “Page 81”.

What’s that you ask? Many years ago (let’s just say before I was a teenager I think) I was staying at my cousin’s grandmother’s house.  On the bookshelf they had a copy of Jaws 2. I started reading it but had to leave before I could finish it. Since I knew I’d be back the next summer I decided to remember what page I was on. I repeated the page number to myself over and over again. And to this day, I can remember, I was on page 81 of Jaws 2 when I stopped reading.  Of course decades later I have no idea what happened in pages 1-80 so the memory doesn’t do me much good. But there it is. It’s still there. Page 81.

As a note, most of this post was based on memory (I had to look up the name of the drug) so some details may be wrong.

Page 81.