The talk was held at Lecture Theater Excellence. The talk was presented by our former Deputy Editor, Nur Nazihah Wardahyani Abas. It was attended by tutors from both department and as well as students from Upper and Lower 6. The talk was about optical illusion. She started with the definition, how it works, types of optical illusion and the uses.
She began the talk with the definition of optical and illusion. Optical comes from word obtain which means something that is related to our shade or sight. While, illusion comes from a Latin word which means to mock. So, optical illusion is a mismatch between the immediate visual impression and actual property of an object.
She further explained on how optical illusion is occur. Optical illusion work due to the property of visual area of the brain whereas they received and also contain information. First, light from the object will be deflected and eventually will enter our eyes. Then, it will be converted into an electrical impulses in our brain to process the information. It takes about 0.1 second for this process to take place. Since our eyes keep on receiving light, our brain cannot process all the information quickly. Therefore, our brain decided to take a shortcut and simplify what we see to help us concentrate what is important. This is how optical illusion is formed. So, optical illusion has more to do with our brain than optic in our eyes.
She continued with some examples of optical illusion. According to her research, there are three type of optical illusion. The first one is physical illusion. It occur due to the physical property of environment and their impact on the behaviour. Example of physical illusion is mirage phenomena. It is naturally occurring optical illusion. It is produced by reflection of light and when light passes through a layer of hot air. Secondly, psychological illusion. Psychological illusion is when the upper part of an object is more light in colour than the bottom part. However, when we split it, it actually consist of solid colour. The last one is coordinated illusion. This can be further divided into disorting illusion and paradox illusion.
She continued the talk with types of coordinated illusion. Disorting illusion are used in different technique to make an object to similar size and length. Example of disorting illusion is Muiler- Lyer illusion. This is when we see the same length of line which one have outward pointing arrow and another have inward pointing arrow. We tend to see the line with the outward pointing arrow is longer than the line with inward pointing arrow. This is because of Assimilation Theory and Eye Movement Theory. Assimilation Theory is when we see the outward pointing arrow is longer because the visual system is unable to separate the figure into parts. So we see the whole figure, the line with outward pointing arrow is longer. Paradox illusion occurs as a result of features of object that cannot exist. Example of paradox illusion is an impossible triangle. We called it impossible triangle because all, the three sides of the triangle is seen to be a head of each other end. This is because illusion in our eyes is an interpretation of 2D pictures as 3D object. Visual perspective is twisted and create illusion of a 3D object that cannot possibly exist because we usually assume that the features of the figure that are touching in the 2D image are at the same distance.
In her talk, she also gives some uses of optical illusion. It is often used in medical field. Scientists use optical illusion to investigate how the eyes and brain processes our visual information while in the entertainment field, artists used it for visual effect and entertaining human being.
During Question and Answer session, one of the students from Upper 6 asked “How does the brain decides what is important?” to which she answered “Well, it is actually depends on the brain how to decide”. The talk was ended with applause from tutors and students.
We would like to thank Nazihah for giving the lecture and also the students and as well as tutors for coming in our talk.
To watch the lecture, watch it on Youtube