Why can’t we walk in a straight line with our eyes closed? We can’t walk in a straight line with our eyes closed because our brain depends on visual cues, and without an external reference point, small random errors in the body’s sense of “straight ahead” build up over time, and the brain has nothing reliable to recalibrate against.
If I put you in a large park and ask you to walk in a straight line for ten minutes, you would have absolutely no trouble at all. If I then blindfold you and ask you to do the same thing, you will walk a very squiggly path, and most people will actually just walk in circles. Some people even walk in very tight circles with a diameter of about 20 meters. However, if you ask them, they feel that they are walking in a straight line. This doesn’t only happen when blindfolded. People who are lost in thick forests tend to walk in large circles, even though they believe they are going straight. This is one thing that makes it particularly difficult for mountain rescue to find them.
When we walk, we might be just concentrating on a podcast, but our brain is making hundreds of micro corrections every second to make sure we are walking in a straight line down the street. Everything starts in the brain, and there are three parts of the brain that work together. The cerebellum is in charge of our balance, posture, and smooth muscle movement. Then the frontal lobe is responsible for planning each movement and the overall movement. Then the basal ganglia is responsible for movement initiation. All of these work together and then send signals down the brain stem into the spine, to make the actual movements. It is not just a case of lifting each leg, but adjusting all of our muscles to keep our center of balance in the right place. The brain does this by taking visual signals, balance signals, and a host of other signals to make those tiny adjustments. The visual signals come in through a fourth part of the brain, the occipital lobe.
When we are blindfolded, the brain loses all of the visual signals. The visual signals are very important because they give us a point to aim at and a way of tracking moment by moment if we are keeping to that point. The blindfolded people used in the experiments were able to keep a much straighter line if it was a very sunny day, because their eyes could see the light and the dark through the blindfolded, giving them some visual signals back. The visual signals also let us see how uneven the ground is and adjust for that. When we are blindfolded, we lose these signals and have to rely entirely on our balance system and our musculature.
One theory for why we drift or circle when we are blindfolded is that we all have a dominant leg and a dominant side to our bodies. The muscles on one side are slightly stronger than the other, and we are not perfectly symmetrical, which means we have one leg longer than the other and usually one foot bigger than the other. This causes no problem when we can see where we are going and make adjustments, but it does make a difference when we can’t see. Over time, and sometimes very quickly, this difference can start to push us to one side. Without any corrections, we continue to move to that side. This is just a theory, though, because experiments don’t always show a correlation between the dominant side of a person’s body or the longer leg and which way they turn when they walk blindfolded. Some people turn one way for a while and then turn the other way.
So, if we cannot use our eyes, we are essentially reliant on our sense of balance. Our balance system is called the vestibular system. There are fluid filled canals in our ears and lots of microhairs that sense the presence of the fluid. As we move our head around, the fluid moves, which activates the hairs, which send electrical signals to the brain. Our brain adjusts the muscles in our body to keep the balance level. It seems, though, that most of us have a slight bias in our vestibular system where the brain gives more weight to the signals from one ear than the other. This might only be a very small amount, but it could be enough to push a person into walking in circles when they cannot see.
Another reason might be that the fact that we can’t see pushes us to think about what we are doing consciously. Normally, all of the actions our brain takes to make us walk are unconscious. When we are forced to think about them, it makes it more difficult for the brain to function smoothly, and it makes us self conscious. Plus, people are probably more hesitant because they don’t want to fall over, which would alter the way that they walk. This is similar to if you have been driving for twenty years and you suddenly start thinking about what you are doing and you find it more difficult to drive. Overthinking any kind of practiced motor skill will make you clumsier. I wonder if scientists will ever prove what the reason for this behavior is. And this is what I learned today.
Sources
https://en.wikipedia.org/wiki/Inertial_navigation_system
https://www.livescience.com/33431-why-humans-walk-circles.html
https://www.npr.org/sections/krulwich/2011/06/01/131050832/a-mystery-why-can-t-we-walk-straight
https://news.mit.edu/2025/staying-stable-animal-balance-1203
https://www.cancerresearchuk.org/about-cancer/brain-tumours/brain-and-spinal-cord
Photo by Alan Cabello: https://www.pexels.com/photo/man-blindfolded-1278620/