The Human Brain—Fill in the Blanks

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God designed your brain to fill in missing details on the fly . . . with some interesting consequences.

Do your pets ever talk to you? Maybe you’ve seen one of those Internet videos where a dog says, “Hello.” We know dogs don’t really speak, despite what we think we hear. So what gives?

God designed our minds to make quick assumptions about what’s going on around us, without consciously studying it. By “filling in” information ahead of time, based on previous experiences and what we expect, our brains don’t have to constantly process every changing detail in our surroundings. This allows us to respond to important changes speedily and accurately.

This phenomenal ability to predict what will happen and then refine the predictions (as we gather new data) is usually a good thing. But it can lead to trouble. Have you ever walked into a room and promptly forgotten why you went there? Turns out you aren’t the only one. Gabriel Radvansky at the University of Notre Dame studied this phenomenon, dubbed “the doorway effect.” He found that crossing into a new room causes people to have trouble recalling all sorts of prior thoughts.

Radvansky proposed the idea that our brain constructs “event models” matching our surroundings. This allows our brain to maximize our readiness for what’s likely to happen next. For example, if you are reading this while relaxing on a couch in your living room, you probably don’t need to worry about a car running over you. But when you’re driving on the highway, you expect traffic problems. When we move to another environment (or another room), our brain replaces the model of where we were with a new model for where we are now. Walking through a doorway seems to trigger this response. Anticipating new needs as you move to a new environment is helpful . . . unless you forget the reason you entered the new room in the first place because it got dumped along with the rest of the previous model!

Your brain not only creates and replaces expected models of the world, it also fills in missing information. When we hear sounds that seem to resemble speech, our brain fills in expected details instead of taking the time to process the sound fully. So you can hear your dog or your doorbell “say” hello!

The ease with which our brains can be tricked is a good reminder of our limitations. We do not have conscious control over everything our senses tell us. Our brain deals with much of that information subconsciously and perceives what it thinks probably happened.

Probably happened? As they develop clearer understanding of how the brain constructs our perceptions, some scientists question whether we can know anything for certain. One researcher has even said that our reality is a “controlled hallucination.” Is that really the best we can do?

God made us in his image, so we know we can know some things for certain. Yet we also see many reasons to doubt ourselves. The only way out of this conundrum is to turn to God our Maker. “Meditate on [his Word] day and night. . . For then you will make your way prosperous, and then you will have good success” (Joshua 1:8). He is our starting point for understanding reality, explained clearly in his Word.

Test It Yourself . . .

Your brain automatically fills in missing information for you all the time. Did you know each of your eyes has a blind spot? You don’t usually notice them because your brain fills them in.

Finding your blind spots is easy! Grab a piece of white paper and draw a small dot. About 6 inches (15 cm) to the right of the dot, draw a small X.

Now hold the paper roughly 20 inches (50 cm) away from your face and close your right eye. Focus your left eye on the X and slowly move the page closer to you.

At a certain point, the dot will vanish from the page even though you know it’s there! That’s your blind spot. Your eye can’t see the dot anymore so your brain fills in that part of the page with white paper.

Next, turn the page over so the X is on the left, and find the blind spot in your right eye.

Heather Brinson Bruce earned dual degrees in English and chemistry from Clemson University. She writes for Answers magazine as a freelance author.

Answers Magazine

May–June 2018

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