Friday, May 20, 2011

Filling in the Gaps

Let's be honest, there is a LOT of stuff in the world. Far, far too much to deal with. Just think about all the sensory information that's assaulting you when you're sitting in a crowded cafeteria or stadium. Your brain is getting all these signals from your eyes, analyzing the signals to pick out intersecting lines, identify distinct objects and figure out what's connected, what's not, where it all is, how fast it's moving etc. It also labels all these objects with their respective names when you need them, and also their uses. On the auditory side of things, there are dozens of different conversations happening within earshot, each sound , and probably a dozen or so ambient background noises running constantly underneath it all.

So what do you do? You cut things out. Prioritize. It's a complicated process, but your brain basically takes most of the information you get, looks at it, decides what's important, and forwards that to the higher levels of consciousness and processing, while the rest gets shunted off in the subconscious, often to be dumped entirely after you don't need it.

Example: You're in this restaurant, and you suddenly hear someone say your first name, and you turn around. You didn't hear anything else they said, but your brain picked up the sounds that make up "your name" and forwarded it up to the higher levels of attention. You weren't following their conversation, but cause you caught some sensory stimuli that was unique and meaningful, it grabbed your attention, and you stopped tuning out their conversation and instead focused on it.

(There are mixed opinions on how much you actually "perceive" or unconsciously follow conversations around you. It seems more likely that your attention roams around every so often and then focuses on anything it considers important.)

So that's a simplistic example of how you tune out, and then focus in on different stimuli. But here's another question. What does your brain do when there's not enough?

But despite the huge amounts of info bombarding you every second of the day, there's still a lot that is incomplete. Just like the image on your TV set gets fuzzy or erratic as the signal gets weaker or your antenna picks up interference, there is a lot of "static" in sensory info too. And in other cases, there are just plain gaps in the information.

Somebody honks a horn while you talk to a friend, and you don't catch one of the sounds they said. A computer would have a huge problem interpreting the sentence, but you don't.
Why not? Your brain fills in the gaps.

To see how it works, let's look at an experiment done by Warren & Warren (1970). People heard a recording of the following sentences.

It was found that the *eel was on the axle.
It was found that the *eel was on the shoe.
It was found that the *eel was on the orange.
It was found that the *eel was on the table.

Right at the asterisk, they spliced in a cough. Each sentence was identical, except for the very last word.
Now the interesting thing is they heard different sounds at that asterisk, in each sentence. What's happening?

Well, as you listen to speech, your brain is constantly analyzing things for meaning, and trying to make sense of what is being said. A lot of this involves picking out sounds, identifying them as words, as parts of speech, etc. In speech, a lot of the sounds we think we hear are actually never articulated. So what the brain does instead is think " I heard 'the eel was on the axel. I've never seen an eel on an axel. They're not generally found anywhere near axels. There was a bit of a cough at the beginning of 'eel', so I'm guessing I missed a sound there. Ok, what is probably on the [axel, shoe, orange, etc]?

And so your brain inserts the sound w to make weel, h to make heel, p to make peel, and m to make meal. This is known as the Phoneme Restoration Effect.

The process by which it decides what word actually was is reallly cool, but I don't have time to go into it, and I'd need to study it as well.

So this is one of many interesting examples of when you hear things that really aren't there. Yes, everyone hears things that aren't there. And here you thought Johnny was special.

Other Gaps which are Filled

You have a "blind spot" in your field of vision. Your optic nerve has to leave out the back of your eyeball, and any light that hits that exit spot isn't sensed. But we don't see any holes in our vision (usually). Why not? Your brain looks all around that blind spot, averages the color, looks at any patterns, and literally fills in the gap. Check this link out if you want to see it in action.

The McGurk effect is a super-cool example of how your brain takes different sensory info and combines it to try and make more sense and fill in gaps. Here's a video which may or may not be cool, cause I haven't gotten to see this particular one.

Wlel, I konw you hvae seen tihs boerfe, but I thuogh taht it wuold be a ufuesl doiaeomrsnttn aynawy. Eevn tohguh olny the first and last leettr are in the right oderr, you're biran siltl ulamnscrebs it.
Yeah, your brain takes the scrambled letters, and puts it more or less in the right order.

In reading comprehension, studies suggest that one of the problems kids with poor reading face isn't simply decoding the letters into sounds, but instead not having enough background knowledge for their brains to "fill in the gaps" in the writing and help them understand what's going on.

Can you all think of other situations where our brain fills in the gap? Or where other things do? If you survived reading this far, go ahead and post your own examples!

I meant to edit this a lot more, and streamline/clarify/cutout a few things. And fix grammatical errors. But I didn't!! Hooray!

Did you notice? I removed the "be" from all my "because"s! And your brain filled in the gaps!


  1. dude, i was totally reading, and i sensed an orange and peanut butter in my periphery while still reading \m/ gap has been filled :D

  2. Removing the "be" from "because" and saying that the brain is filling in a gap is inaccurate, because "cause" is a very common shorthand. It is like saying the brain is filling in a gap when you say "it's" instead of "it is."

  3. Although it is a common shorthand, that shorthand came about when people started cutting off the first syllable of "because". You naturally accept it as normal and understandable, because it's a very small jump, and has been around so long.

    But think about this.

    "Cause" is a noun, defined as:
    1. The source or reason of an event or action
    2. A goal, aim or principle, especially one which transcends purely selfish ends.

    "Because" is an adverb meaning:
    1. (archaic) For the reason (that).
    2. On account (of), for sake (of).

    Your brain doesn't usually go to Webster's to find out the meaning of words in normal conversation and text. It just looks at the sentence, sees "cause" and thinks about the times it's seen "cause" in similar contexts, and what it meant then. It also looks at the grammar, and realizes that putting a noun in the spot "cause" is filling wouldn't make any sense, so it takes the adverb definition, even though grammatically that would be incorrect.

    So it is filling in a gap, in a small and fuzzy way, but only as much as it does in any reading or conversation we have, which is what I was pointing out.

    I find the growth of languages and slang to be extremely interesting.

  4. Oh! I forgot.
    Because can also be a conjunction and an interjection as well.

  5. Yay for heuristics! They are often flawed and incorrect, but without them we wouldn't be able to process anywhere near the amount of stimuli we do.

  6. WOOOOOOOOOOOOOOOOOOOOOOOT! i like reading stuff that sounds smart cus then i feel smartish!

  7. That exercise on wiki hurt my eyes... I think I did it too many times