Lesson 6 and 7: Sense Perception

(Lesson 6 – Friday 11th October, Lesson 7 – Tuesday 22nd October)

Optical Illusion:

Do we trust what we see? Can we say for certain that what we see or what we perceive to see is actually true/real?

This also relates back to one of the first lessons when we learnt about selective attention. Selective attention can be applied to sense perception because if you choose to focus on something and force yourself to see something even when you don’t actually see it in the first place, you may end up being able to see it eventually. However, if you did not know of it in the beginning you may be completely oblivious to it and therefore may automatically arrive to the conclusion in your mind that it doesn’t exist.

Just because you cannot see it, does it mean it doesn’t exist? And just because you can see it, does it mean it does truly exist?

For example, using the text shown below, let’s see if you can read and understand it, because I was able to (or I think I was able to) despite the individual texts not actually being the proper English Language. I was able to read the individual texts and made them into complete sentences, “According to a research at English university, it doesn’t mater in what order the letters in a word are, the only important thing is that first and last letter is at the right place.”

However when we physically see the text, it doesn’t actually say “according”, instead it says “aoccdrinig” therefore this leaves us to question ourselves whether we see things that actually doesn’t make sense in plain sight but subconsciously try to rationalize and to interpret it in our brains so that we seem to understand it.

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Another example is the ‘Munker White Illusion’. Here are some pictures to explain this illusion:

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The grey bars between the black bars seem darker than the grey bars between the white bars. However when the black bars are removed from the background, it is clear that the shades of the grey bars are the same color. Darkness of the black bars has affected our perception of the bar’s color.

And the final example is the ‘checker board illusion’:

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At first we assume that tile A is darker than tile B because of the shadow created by the cylinder on the right corner. However, when the surrounding shadow and the cylinder is removed, it is clear that tile A and B is both the same color.

This applied for the ‘munker white illusion’ as well. Our brains compare the surrounding environment by comparing color and context in order to create our perception. We see things in a certain way so that we can interpret what we see as efficiently as possible and allow us to interact with our environment most appropriately.

For example, for the ‘checker board illusion’ the brain compensates by interpreting tile B as a lighter color when there is a shadow around it because we know that a shadow will cause a color to be a darker color than its normal.

(^ Snapshots for the munker white illusion and checker board illusion were taken from the YouTube video of “Can you trust your eyes?” by AsapSCIENCE)

Scientific explanation of how we see things:

Here are some diagrams showing scientific ways of explaining how we see things through our eyes. The first two diagrams shows how the eye adjusts depending on when it is focusing on an object that is close or on an object that is far away in the distance.

How the eye physically works allowing us to see objects and how our brain interprets what we see: First of all light is reflected off an object and that light travels into our eyes through the cornea and the pupil in a straight line. When that light reaches to the back of the eye, an upside down image is projected onto the retina and the photoreceptors in the retina then translates the image into electrical impulses that travels along the optic nerve and into the brain. The brain then interprets what we see by visualising the image we see and for example, if we see a wasp or a bee in front of our eyes our automatic response after interpreting that information would be to lean back in a fast motion or to simply take a few steps back.

McGurk Effect:

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McGurk Effect: hearing lips and seeing voices

The McGurk Effect challenges us between the interaction of hearing and the visual appearances we see in speech perception, leading to the question – can you trust what you hear in correlation to what you see? The McGurk Effect will clarify this for us.

The McGurk Effect is a video of a close up on a man, where they show two different clips: the first clip is where the man is contracting his facial muscles and saying “ba” where in the second clip it is of the man that appears to be saying “fa”. Or at least, his facial contractions appear to be motioning it. However in reality, both clips were of a man continuously saying “ba”. The second clip was dubbed over with the “ba” sound. However, when the clip was shown to my whole year group, everyone did not believe so, and instead believed that the man in the second clip was saying “fa”.

 So this leads to the question of how and why our sights influences what we hear. First off, how? Well the result of this experiment suggests that speech perception is multimodal and therefore it requires information from more than one sensory that can provide us with. Which leads us to the next question, why do we use both sight and hearing in speech perception? Well one of the most obvious reason is that it allows us humans to have more efficient communication and interactions with one and another. For example, if you only use one sense such as hearing and you were communicating with a friend and you were being sarcastic therefore the words you express contradicts  with what you actually want to say, that friend may not be able to understand if it is a sarcastic remark or a joke unless they see that friend’s facial expressions because it will show emotions such as a smile or a disappointed look. That friend will incorporate these two information to figure out in their brain if the person is joking around or if the person is serious. This is vital in communication to understand and interaction with others.

But it is difficult to interpret information from using one sense alone. For example, like people who have hearing deficiencies can compensate by learning how to read lips. However, this requires more work and effort than those who can communicate by using both hearing and sight simultaneously.

Resources: About the McGurk EffectThe real and illusory in phoneme perception <– Here is a link showing a full analysis conducted by these two researchers on the McGurk Effect (including discussions and conclusions)