McGurk Effect – What You See is What You Hear

By Anupum Pant

Do Not Cheat

  1. Close your eyes: Before you watch this video, you should know that, when you watch it for the first time, you have to watch it with closed eyes. Well, you can’t ‘watch’ with closed eyes. It simply means, you have to just hear the sound track first. I’m sure you can do it because closing eyes for 5 seconds is not asking for much. I don’t have any veiled interests here. It is for you. You won’t appreciate the effect if you keep your eyes open during the first go.
  2. Open your eyes: Watch it again with your eyes open. Be calm. It happens to everyone.

So that was the McGurk effect. It is a perfect example to show that accurate perception of reality may involve more than one sense. This is called “Multimodal perception”. In simple words, our senses do not learn from the surroundings independent from each other, they work together and learn together to help us perceive information.

The video

The video shows a man moving his lips as if saying “Ga” or “Da”, although it is just a visual of him saying that, let us call this the visual for the first sound (“Da” sound). The second sound is the “Ba” sound that is actually playing – this is the second sound.

When your eyes are closed, you hear the correct sound, the second sound – the “Ba” sound.
When you watch it again with your eyes open, you hear the “Da” sound. The brain combines the visual and audio signals to make you believe that the sound you are hearing is actually “Da”. Even if you are aware of this illusion, your brain doesn’t correct it for you, no matter how many times you repeat this.

Some interesting things about McGurk effect

  • You can focus anywhere on the face (not just the mouth) to perceive the same effect.
  • Women show a stronger McGurk effect than men.
  • Normally, people with mental disorders do not hear much difference in the sound with eyes open or closed.
  • By the age of 4 months, infants are able to identify facial movements and relate them to sounds. So, even infants show this effect to a certain extent.
  • Information rich perceptions are easier to remember. So, the next time you are trying to learn something, involve more senses. Probably involving a particular smell that goes with a piece of information will help you remember things well. Or a sound, maybe.

Note: Since my posts were getting longer everyday, I’ve tried to keep this one short. I don’t want the posts to be overwhelming for people who are not used to long reading. This blog is meant to make science sound interesting to everybody, not to scare them away from it. I’ll be waiting to receive your feedback on this. You can get in touch through twitter (@indigoanalysis)

Is There a Scientific Explanation for Everything?

By Anupum Pant

Today we have Dr. Eben Alexander III, an American Neurosurgeon and the author of a number one New York Times bestseller, in the house. Well, not really, but let us imagine he is here with us.

Background: Dr. Eben Alexander has been a member of the American Medical Association, a neurosurgeon and has taught at the Harvard school of medical sciences. He has spent a lot of time among scientists believing that there is always a scientific explanation for everything. But, one day, he experienced something that defied all scientific explanation. Turns out, there isn’t a scientific explanation for everything. Later he went on to write a number one New York Times bestselling book – Proof of Heaven: A Neurosurgeon’s Journey into the Afterlife.

Like logical open-minded Possibilians, let us read the book first, to start arguing against it. I haven’t read it yet. So, for now, I’ll stick to writing about just what I’ve learnt about it, rather than formulating theories against it.

The story: In the year 2008, Eben was affected by a severe case of bacterial Meningitis and fell into a coma for 6 days. His Neocortex showed no signs of activity. When he got cured miraculously (with just 2% survival chance) and returned from coma, he had experienced something out of this world. According to him, during the coma, he had experienced a vivid journey into the afterlife – kind of a near death experience.

The experience: When he fell into coma, he found himself in a dark and suffocating place for a very long time. Later a spinning bright light with a beautiful melody came in slowly and “rescued” him out of this agony. It took him to a fertile green land. Some points that he makes about this mysterious land:

  1. There was no need for a spoken word to communicate there. Every communication was telepathic.
  2. The instant you asked questions, you knew the detailed answers for those questions. (Something similar to the experience of Zen)
  3. The experience was more real than real-life. In comparison, real-life seemed like an illusion.

You can watch a 42 minute long interview here for further details. [Video] I’d also suggest reading: Supernatural: Meetings with the Ancient Teachers of Mankind


Although we’ve progressed a lot in science and technology in the past 400 years, there is a much more science doesn’t explain than there are things it can.

For instance, to make our equations sound right, we assume there is something out there we can’t touch, feel or sense in any way; we choose to call it dark matter. The most incredible thing – 90% of our universe is dark matter (and dark energy). That is too much to sweep under the rug. And we know nothing about it.

In the words of David Eagleman – “Our ignorance of the cosmos is too vast to commit to atheism, and yet we know too much to commit to a particular religion.”

Or in the words of Carl Sagan – “An atheist is someone who is certain that God does not exist, someone who has compelling evidence against the existence of God. I know of no such compelling evidence. Because God can be relegated to remote times and places and to ultimate causes, we would have to know a great deal more about the universe than we do now to be sure that no such God exists. To be certain of the existence of God and to be certain of the nonexistence of God seem to me to be the confident extremes in a subject so riddled with doubt and uncertainty as to inspire very little confidence indeed.”

The Purpose of Sleep – Theories

by Anupum Pant

Did you know?

  • You can live longer without food than you can live without sleep.
  • On an average, a person sleeps for 1/3rd of his life. That means if you are 30 years old, you’ve slept for 10 years already.
  • The world record for the longest span remaining awake is 11 days. The record was set by 17-year-old Randy Gardner in 1964 when he was awake for 264 hours and 12 minutes. (Don’t try this)
  • If it takes you less than five minutes to fall asleep then very likely you are sleep deprived. It should take about 10 minutes normally.
  • You can lose up to 2 grams every minute while sleeping. That comes to about a lost Kilogram at night.

What is Sleep?

Everybody sleeps. On an average, everyday, a bat sleeps for 15 hours while just 3 hours are enough for a Horse to feel rested [How much do animals sleep – chart]. Dolphins can sleep with half of their brains active and even the smallest of worms need sleep. But, till date, scientists haven’t been able to reach a consensus on why we actually do it?

Sleep can be understood as a life sustaining activity. It can be compared to another of our important activity – eating. These strongest of the human urges – eating and sleeping – serve a nearly common purpose – quell the urges; just as eating relieves hunger, sleeping relives sleepiness.

While it is true that we may have not been able to spot the primary purpose of sleep, years of research hasn’t gone wasted. With time, we have learnt a lot more about sleep than we used to know 50 years back. There have been hundreds of practical and impractical theories on why we sleep. I’ve mentioned a few of the realistic ones here.

Purpose of Sleep – Theories

Inactivity Theory:

According to this old theory, sleep evolved out of the need to be safe. It suggests that inactivity at night is an adaptation that serves as a survival mechanism. It functions as an activity which would keep an animal safe during the time it is most vulnerable e.g. Humans are vulnerable at night because they don’t see well in dark.

This theory is easily countered using the argument: Being conscious and still, is much better way to stay safe than lying unconscious and still.

Energy Conversation Theory:

It suggests, the main function of sleep is to reduce the demand and consumption rate of energy at times when searching for food isn’t an efficient option. Some believe, that this theory is a part of the inactivity theory. But, unlike the inactivity theory, this theory has been bolstered by various experiments which prove that the consumption of energy is reduced when an organism sleeps.

Restorative theory:

It explains sleep as an opportunity for a body to rejuvenate in terms of muscles, tissues, proteins, cells and growth hormones. Also, during sleep, the body clears an accumulated molecule called adenosine from the system, and makes us feel alert when we wake.

recent study also seems to support the restorative theory in a fresh manner. It says, brain accumulates toxins [like beta amyloid] while it is awake. The concentration of such toxins keeps increasing during waking state. The study observed an increased activity of spinal fluid being pumped into the brain in rodents (hasn’t been studied on humans yet). This spinal fluid functions as a medium to pump out toxins from the brain. This theory could be a breakthrough in the study of causes and prevention of Alzheimer’s as it is known that toxins like beta amyloid cause the disease in humans [How beta amyloid causes Alzheimer’s].

Brain Plasticity Theory:

According to this, sleep plays a critical role in brain development. Infants (age when the brain develops the most), for example, sleep for about 13 – 14 hours every day. On the other hand, the poor ability to learn and perform tasks due to the lack of sleep explains the role of sleep in adults. Since, It has been proven that brain is highly active during sleep, this theory remains the most plausible one in being able to state one of the functions of sleep.