Hello everyone and welcome back to the ISC guide. Today we'll be starting with unit 3 which is attention and perception. This in my opinion is a very fun chapter because it is mostly for visual learners.
If you are a visual learner, this will probably be your best chapter and I do think that the best way to learn this chapter is to understand it visually. Okay, so let's get right into it. First of all, we'll start with a brief introduction about attention.
Attention is the concentration of awareness on some phenomenon by the exclusion of other stimuli. Selective attention is the selection of important stimuli which are limited and should be focused upon. And sustained attention is our ability to concentrate on the selected stimuli for longer durations.
Attention in a general sense, we all understand. Teacher says pay attention to what I am saying or what I am teaching. That is basically our attention. When teacher says this, what...
the teacher is trying to ask of us is to heed to the words and listen to what they're saying so baki jitne bhi distractions hai maybe there is a crow outside the window that you're looking at ya fe there are other students outside the class door kiya un loko dekh rahe ho to un loko pe focus karne ki bacha hai jo teacher ke words hai to teacher pada rahi hai un pe focus karoge that would be better iske le bolte attention selective attention is very important to our existence even imagine karo you are in a very crowded room and sab log ke conversations ek saath ho rahe hota hai and imagine that sab log ke conversations toh mein ek saath hi ek intensity pe suna hi de rahe hai that would be very chaotic wo possible nahi hai iske liye we have the ability of selective attention jisme am log saif ek cheez pe ya fe maybe do ya teen cheez pe focus kese kta hai toh if i am in a crowded room and i am talking to somebody a massive whole conversation My attention will be selective on that. And the conversations that are around me, my attention will be either less or not at all. Sustained attention is basically our ability to concentrate longer.
Sustained means longer for a longer period of time. There are two types of attentions. Voluntary and involuntary. Voluntary attention requires cognitive efforts to be made. When you are solving a sum in math, then you need...
attention you need to pay attention to the sum or you have to solve any table in your mind for all that you need voluntary attention which you grant with your willingness attention to that stimulus then we have involuntary attention it doesn't have any cognitive efforts and it is not in our control it is determined through several physical and psychological factors Now we will see what are the physical and psychological factors. Basically, we don't have to do involuntary attention on our own. Let's go back to the example of the party. When a conversation is going on, I am mostly focusing on that one conversation. But let's say from the other side of the room, somebody calls my name.
I can still hear it even though I am intently focused on the conversation I am having at hand. Even then, I can still hear my name. Right and there are many factors, physical and psychological, which we'll look into now. Okay, here what I've done is I've visually represented all the examples.
So when I changed the slide, the first thing I'm sure you would have seen this. Bigger, the word bigger. Because it stands out the most in the whole slide. And you must have seen this later because this is very small. So why does this happen?
When you're writing the answer for this, Physical factors and psychological factors. Always write it in this format. This is the best format. Attention first. Then what is perception.
Then an example of that. That's more than enough. You can elaborate a little more. I have given this in bullet points type. Write it in proper sentences.
It doesn't work as equals to signs. If it is bigger size, you will pay more attention. If it is smaller size, you will pay less attention.
Perception is that the bigger the size, the more important it is and smaller size is seen as less important. An example would be a big billboard demands more attention than a small sign. Imagine a big billboard on the road and a small sign.
Of course, more attention will be towards the bigger billboard. Even though their content is the same, color is the same, everything else remains the same, there is only a difference in size. Still, the bigger billboard will come first notice. The second factor that we have is color.
More attention is paid to bright and contrasting colors and dull and neutral colors are given less attention. Why? Because when we perceive it, bright means urgent and important or dull means insignificant.
Example would be neon green sign demands more attention than a grey sign. Especially when you are on highways, if you have driven on a highway at night, then red markers remain, neon yellow, neon green markers remain. So that when the drivers are driving, especially at night, we can very easily spot where the road is going.
Because they can't light streetlights everywhere. Movement and change. Now as you saw, the text...
came left to the whole screen that was movement so maybe it came in more focus right, attention, moving object has more attention stationary object has less attention moving objects are perceived as more important stationary objects are seen as less important basically remember one thing whoever is given more attention why is that attention given more? because we perceive that as more important very simple to remember Example, a moving car demands more attention than a stationary car. Abhi road pe chal raho, side mein bhot saare stationary cars packed rehti hain. But then saamne se ek speeding car aari, of course zyada attention will be paid to the speeding car. Then we have change.
Sudden changes, more attention and slow changes, less attention. Perception, sudden is urgent and important while slow is insignificant. Sudden change of a color of a light demands more attention than a slower, more gradual change.
Okay, this phenomenon will be very common. Let's say you meet a relative once every one year. Okay, annually you meet that relative.
And you are meeting your parents every day. So when you meet a relative, what do they say? That you have grown taller. They see all these small changes more evidently.
Your parents might not notice it because they are seeing it everyday. That's a gradual change. But for them, it is a very sudden change.
That's why they are able to give more attention. They see more importance. That's why they state it. Then we have intensity. High intensity is more attention.
Less intensity is less attention. Objects with higher intensity are perceived as more important. Objects with less intensity are seen as less important. A moving car demands more attention than a stationary car.
Here we have given the example of moving car because intensity can be perceived as speed also. This is more relevant for movement but here just for understanding sake, intensity because we can take it in many cases. So intensity can also be taken as the speeding of the car. So the more speed the car will have, we will pay more attention to it.
So with what intensity it is moving. or what is the intensity of the color intensity can be of varied types then we have contrast here when we change the slide white here the white and this orange this contrast makes this orange highly visible and this orange is less visible because this is a very non contrast orange so for high contrast we have seen this low contrast is less attention is killer second I'm Logan a deca perception high contrast is urgent and important low can low contrast is insignificant example black text stands out on a white page while gray text is less noticeable see this you peachy car basis white background is the black box of the standout car that you can see it very clearly and even though give both similar texture If you can see this, it doesn't stand out that much. Why? Because there are no contrasting colours.
This is a very jaundiced lemon yellow. This yellow doesn't stand out that much on this page, as much as the black one. So for this, when the contrast is high, we can pay more attention, rather than when contrast is very low.
Now we have psychological factors. Psychological factors. First comes need. More focus on objects and stimuli that fulfill our needs.
Perception. Need-fulfilling objects are perceived as more important and objects that don't fulfill needs are seen as less important. Example, a hungry person will notice more food stalls. If I have a need to eat, example for when I am hungry, then I will feel more like eating.
Or else, because I will be thinking about food more, then we will notice more food stalls. Or else, if I am very thirsty, then I will see a can of Coke everywhere. or a water fountain which mostly most of the time i would have ignored but when i am thirsty i will notice them more so when there is need then specific stimuli the stimuli that fulfill our needs on them most focus is given secondly we have interest interesting stimuli demand more attention less interesting stimuli demand less attention if someone object or stimulus interesting hai, that means it is engaging. If it is not interesting, it is boring. Example, music enthusiast will notice an instrument being played in public.
If you know how to play any instrument, piano, violin, guitar, anything, and it's heard in public, then you'll notice it more than others. Why? Because you have an interest.
That's why. Right, plus, since you have an interest, maybe you are able to also pay attention to more of the details, that he's playing the wrong chord, or he's missing a tune, or his guitar isn't properly tuned, something like that. All those little- mistakes we will also notice since you're a music enthusiast since your interest is there. Lastly the last psychological factor is emotion.
Emotional states heighten attention to relevant stimuli. Emotionally relevant stimuli are perceived more vividly than natural stimuli. This is a lot especially we experience this during thriller movies and horror movies. So whenever we are in a state of fear A person will get scared even of the faintest sound.
If there is a small door creak, he will get scared too. For this, emotional factors heighten our attention towards specific stimuli. These three are psychological factors. I need you to notice this and I need you to note this. These are related to specific stimuli.
Need is only the object or stimulus that fulfills our needs. Interests. While our point only applies to any object or stimulus that is interesting to us and similar for emotion too.
It will only happen if it is related to that specific emotional state. In fact, when we are emotional, let's say we are very angry, then we will notice more infuriating things around us. Once a person gets very angry, then he starts getting more irritated even of the smallest things if he notices. Even though As per happy things we have we'll notice those happy things less and focus on the negative more. For this emotional states heighten our attention towards factors or stimulus that are more relevant to the emotion that we are experiencing currently.
Okay now we have transformation of sensation to perception. This one involves a little biology so I'll try to keep it simple. But if you have already studied biology in 9th and 10th, then it will be very simple. Especially if you have biology now, then it is of very basic level. For those who don't know much biology, I'll try to keep it simple.
The first stage is sensation. Of course, we are starting with sensation and ending with perception. Because that is the stages of transformation we want to tell. The first stage is sensation. When we touch something, Okay So our Let's say we touched a laptop with our finger So we can feel its texture So this is an example of the stimulus that we are sensing Our nervous system is spread out throughout our entire body Our nervous system is spread out throughout our entire body And the nerves that are present on the skin are called sensory nerves Or sensory neurons These sensory neurons have sensory receptors It doesn't need to know its working working, just remember that it has receptors What these receptors do is they detect what we have touched How does it feel, what type of texture it has, it picks up all these things Okay, so this is our sensation stage The second stage is transduction, the sensory neuron that has got input in this That is changed into electrical impulses Electricity travels very fast, right?
The brain works on electrical impulses. So basically our neurons actually work on electrical impulses. And our brain is made of neurons.
That's why the brain works on electrical impulses. Next stage we have is transmission. These electric impulses that have been transducted from the input from the sensory receptors.
These are transferred neuron to neuron to neuron to neuron until they reach our brain. How does it get transmitted? By a process called the sodium pump.
No need to go into detail. Basically, if you can see this neuron diagram. Okay. This is the neuron diagram. The things that you see here, the roots and branches, are called dendrites.
These are the receptors. Okay. Here, the receptors are...
If this was a sensory neuron, then there would be receptors here. After that, what happens? The electrical impulse that goes through this, this is called the axon.
As you can see here, this is the axon body. So, there are a lot of ions around the axon body. Ions are small particles with charges.
If you are not interested in this, you can just skip it. It is not necessary to write this. But if you find it interesting, stick around. I find it very interesting. So this is an axon body.
And it has ions around it. And when it is polarized and depolarized, electrical impulses travel from it. This is all you need to know. The ions are charged particles.
with that and polarization and depolarization is also related to charges so the constant polarizing and depolarizing transfers the electrical impulses this is the cyton or the cell body from the axon and then we come to the terminals now these terminals, these roots, the root type structure they connect with this, the next neuron here we can see the synapse That is a space that is between this tip and the space between this tip. We call that synapse. And now you must be thinking that how do electrical impulse jumps in the middle?
That happens due to neurotransmitters. Neurotransmitters will be used a lot in 12th in the disorders chapter. There are different neurotransmitters that function. What disorder it results in, high or low, everything will come.
So, we should know about neurotransmitters. Neurotransmitters are basically chemicals that help to forward electric impulse through synapse. Why? Because the neurotransmitter that is released, when it is received by this, it acts like a stimulus for this.
So, when we touched, let's say a laptop, so our first stimulus was, went from here in electrical impulse, It came to the synapse, neurotransmitter was released in the synapse and then the cytone or dendrite of the next neuron received it as a stimulus then it was formed in the electrical impulse and this cycle continues on and on until it reaches our brain. What happens in the brain? In the brain, there is the stage of processing.
So the electrical inputs that we are getting from the neurons, that is processed. And feature recognition starts. So let's say the information that is coming in the form of electrical impulses, we are getting to know that the texture of the phone or the texture of the laptop is very glossy.
We are getting to know this from the input. So we will process it in such a way that it is glossy. We have all these things.
Otherwise let's say you are seeing something. So that is also our stimulus. Let's say you are seeing an apple. So the information that is coming from your optical neurons, the neurons in your eyes, to the brain, what will it do?
There is an apple, it is red in color, it is a little circular, it has a brown thing on top. By doing this, you send information in very small bits. And then it is interpreted together in the stage of perception.
So the stimulus that we get. Let's say we are observing the apple but there could be more behind it. There could be bananas, watermelons, etc.
But if we want to focus on the apple, then the stimulus is selected that we have to focus on the apple first. We can say that the yellow apple is visible, maybe it will be confusing. We have the banana behind us but we are seeing the apple as yellow, so there is some mistake in processing and perceiving. Right, the stimulus selected, organized and interpret based on past experiences, knowledge or concepts.
This is very simple. It's just telling us how perception is. So, what's happening here is the apple that we saw, we recognized it as an apple.
And we can take further steps. We can interpret what to do next. If there's an apple here, then it's probably a fruit basket.
Now, we'll start with the interesting part. And everything from here is 99% visual. First of all, we have the figure-ground principle.
It is a gestalt principle, we had read about gestalt psychologists in the first unit, used in perceptual organization. It divides a perceptual world into a figure and a ground. What is a figure? It is the object that has a shape and a position, and ground is the background which extends behind the figure, and it has no shape or position. It helps us focus on the figure, otherwise the world would be very chaotic.
Okay, we understand this example better. The figure ground principle. While talking to your friends in class, your teacher calls on you. Your figure shifts from your friend to your teacher. Imagine you are sitting in class.
You are talking to your bench partner about something. When you are focusing on that conversation and you are only talking to your bench partner. There the figure is your bench partner. And the one who is walking around in the class. There must be more kids talking behind you.
Or the teacher is teaching. So this is your ground. You are not focusing on it.
But it is still there. We are perceiving it. It is not like when I am looking at the bench partner. Everything else is black.
We can still see around. We know something else is going on. But we are not focusing on it. So this distinction between objects that are focused on. And objects that are just in the background.
This is the figure ground principle. And when teacher calls your name. So our figure shifts.
Then we are not focusing on just our bench partner, but we are also focusing on our teacher, that she will ask questions to me, she will scold me, whatever is happening in the class. Then we start focusing on that too. And if we stop talking, then our bench partner becomes the ground and the teacher becomes the figure.
Okay, now let's see an example of this. This is probably the one that you will also get in the paper because it is the most famous. This is the two faces and a vase diagram. Now here when you see this one, the more prominent is the two faces.
And the vase in this is more prominent. Why? Because these two are black. In both the pictures, the black is more prominent. Why is that?
Because the rest of the picture is white. And since it is white, the vase, what our brain is doing, it is including it in the background. It is including it in the background.
Okay? This is the ground. We are including it in that and that's where these two faces become the figure. And the faces here become the ground and the vase becomes the figure.
Because it is more distinct. So we focus on this and pay more attention to it. Next we have laws of grouping. And as I have written here, I hope you write it the same way. This is more than enough.
Laws of grouping are simple principles given by gestalt psychologists on how our mind tends to group individuals to lie together in the perceptual world. First of all, the law we have is law of similarity. Individual stimuli with some similarities are grouped together.
Example, red and blue dots are perceived as distinct groups rather than as a whole group or individual dots. So when you are writing this answer, first law, then its definition in one line, then the example. The example you are giving, you have to draw it with a pencil.
say maybe instead of Of course, red and blue pens can't be used together. Circle it and square it. Something like that. Make any distinction like this.
Here I gave red and blue dots because it's easier to explain. So here I have these dots. When we observe this, we are seeing this as a red rectangle of dots and it's a blue rectangle of dots. We are not perceiving it as individual dots.
Or we are not considering it as a big triangle. No, these are... two distinct rectangles one is red and one is blue i'm looking at say observe current this is the first law of grouping okay so two laws of grouping are basically individual similar case a group or at the individual stimuli are grouped in a rectangle here instead of a big rectangle though a local rectangle man Q Q key based on similarities of the characteristics a similar key their colors is kill your look red rectangle and blue rectangle may divided Second, we have law of simplicity.
Law of simplicity is also called law of pragnance or law of good figure. What happens in this? Complex stimulus is perceived as several simple stimuli. Example, instead of perceiving the rings as one, they are seen as individual rings. Now, imagine this figure, which looks like an Olympic ring, as one single shape.
It will be very difficult to even imagine. And this is a very complex shape if you look at it like this. But, as I have colored it here, what you are seeing instead of one shape, How is it perceived?
As individual rings Instead of being one, it is being seen as a group of individual rings This is not one single stimulus These are five different rings We are seeing it like this That is why this is the second law of grouping Third is the law of continuity In this, individual stimulus is perceived as being smooth For example, dots are perceived as an S rather than individually These dots can be randomly place but we can see this S like this exact figure we are perceiving it like this why instead of individual dots because it comes in law of continuity our brain smoothen things out so this smoothen things out shape that is the S that is why we can see this S law of closure observed gaps are perceptually filled based on past experiences or knowledge example figure is seen as a diamond rather than just four weeks now you are looking at this figure You'll see it as a diamond. Your brain automatically fills in these spaces. Whatever these spaces are, they fill in. And if you see this shape, you'll say that it is a diamond.
You won't see it as 4 different Vs. It's not an individual stimuli. They are grouped together into one big figure, which is a diamond. Then we have the last law, which is the law of proximity. Everything is the same here. There are still dots.
Color is also same, only difference is their space. So, the ones that are closer together, right, in which the proximity is less, those who are closer together, they are grouped as one. And when they are far apart, they are grouped differently. Similar that are closer together are perceived as one.
Example, dots are perceptually divided into two groups, despite there being no other difference than space. And there is no difference in these figures. But still, we call it group 1 and group 2. 2. Next we have constancies. First of all we have size constancy.
Constancies are all tendencies of our brain. The tendency of our brain to perceive objects as having the same size even when the image cast by the object on our retina changes. This is due to relative size being compared to the surroundings.
Imagine a car that is moving away from you on a road. As it is moving away, the car gets smaller and smaller. And since it is getting smaller and smaller, we could have seen it as the car being physically shrinking.
But we know that the car is not being shrinked physically. Why? Because based on its surroundings, we are getting to know from its surroundings. For example, there is a tree that is also at the same distance. So that tree is also small, but we know that trees can't be this small.
So based on that information, we know that the car is not actually shrinking. It is only moving away from us. even this image's example plane se dekh rahe hai, these houses are so small, these trees are so small, people toh aur shote dekh rahe hongi hai.
But still we know ki actual bade houses hai, these trees are very big, yeh bada island hai instead of just a small circle, jo hamare plane ke wing jitta bada hai. Hum log usko aisa nahi dekh rahe hai. Kyo?
Kuki we know that we are high in the sky, iske le size constancy maintain kiya jata hai when we are perceiving it. Next we have shape constancy. It is the tendency of our brain to perceive objects as having the same shape even when the image cast by the object on our retina changes. This is due to orientation being compared to the surroundings.
So when we open a door, let's see this. When the door is closed, it is a rectangle. When we open it, it becomes like a trapezium.
It is more evident here. But why do we know that it is still a rectangle? Due to shape constancy. We know that when the orientation of an object is changing, it does not mean that its shape is changing.
That is our shape constancy. We will not notice it as a trapezium. We will still perceive it as having a rectangular shape. Next we have colour constancy.
The tendency of our brain to perceive objects as having the same colour even when the lighting changes. An apple does not change colour when we see it in day or night. Now here, a bell pepper, capsicum, shimla, mitch, whatever you call it I'm not sure whatever you call it, drop it down in the comments In normal light, this is a red capsicum This is normal white light. In green light, we could have seen it as being green capsicum.
But we still know that it is red and we still see it as red. Even under blue light, we don't see it as blue capsicum. It is still a red capsicum.
So even though lighting is changing, the color remains constant. Then we have brightness constancy. It is the tendency of our brain to perceive objects as having the same brightness even when the lighting changes. A white paper is equally bright in the day and at night. So a white paper, even if let's say you are studying in the sun.
So as bright as it is in the sun and then you go under a tree. There also that brightness is maintained. Even when we look at this.
Here there is light. The brightness of this paper is same as this. Even though it is under the light and it is in shadow.
Those are all our constancies. Now we have monocular cues of depth perception. What are monocular cues? These are the cues that help us perceive. depth using only one eye.
It's just one eye that we can perceive depth. Those are the monocular cues. The first cue is our texture gradient.
Textures of objects closer to us are clear while textures far away are smooth. Basically, the monocular cues help us in depth perception. What is depth perception?
Depth perception is our ability to know how far things are or how close things are. That's all. Example here, we have blades of grass.
Let's look at this image. The plums are nearby, I think. These plums, we can see the dot here. These are red, these are blue, these are black.
We can see it differently. But as it's going away, especially in the last rows, we see it as a constant color. This is a constant purple. Instead of different reds, pinks, purples and blacks.
It becomes a constant colour. So the texture remains, it is changing. Next we have shadow.
The direction, shape and intensity of an object's shadow tells us about its 3 dimensional figure. What is the depth of an object? It is the depth of 3 dimensions. 1st dimension, 2nd dimension, this is our 2 dimensional shape, that is a circle.
There is no depth in it. But, when a 3 dimensional figure comes, it does have a shadow. So, shadow cast by tree during the day. One example is done. Here, this is more visual.
So, this is a circle. This has no shadow. So, we are seeing it like a 2D figure.
But here, we can call it a sphere. Why? Because this has a shadow. Light is coming from here and this is casting a shadow.
So, we can say that this is actually a 3D figure. And a 3D circle is a sphere. So, we can call it a sphere. Even though, since... Laptop, TV, phone These are still circles only Because the screen is a 2 dimensional screen You can't see it in 3D Next we have interposition When objects overlap The object on top is seen as being closer to us A tree in front of a house If you see a house and there is a tree in front of it Of course the tree will be closer to us Here too Blue and red rectangle What is closer to both?
of course the blue rectangle even though there is no shadow we can still tell because it is interpositioning this is overlapping so the one in front we can say it is closer to us next we have relative size when objects are farther away they look smaller and larger when closer you can do the car example a car gets smaller as it drives away the object is getting smaller the surrounding trees are also getting smaller The electrical poles have also become smaller. The scooters and scooters have also become smaller. All these come in relative size. So the relative size is very small at a certain distance. We can say that is small.
Since it is small, it is that far. So our relative size is given. Look at this. Here the black ball is closest to us.
Why can we say this? Because its size is the largest. If you compare its size to let's say this orange wall, the orange wall is smaller. Even though there is no overlapping here, we can still say that since the orange wall is smaller, it is farther away.
Next we have linear perspective. Parallel lines seem to converge as distance increases. Railway tracks converging. Here you can observe this phenomenon.
These are parallel lines. We know that rails run in parallel. But still, the farther it goes, they are appearing to converge. And with the help of convergence, we can say that the more converging it looks, the farther it is. Here, the most important thing is that the converging is not the same as the converging.
Convergence is the closest to the ground. Next we have aerial perspective. Aerial perspective means that due to the atmosphere, objects farther away look more blurry while closer objects are sharper. Grass in front is sharp but mountains are blurry. We can even count the petals on these flowers.
We can see the blades of grass, the stems of the flowers. But the further it gets, this mountain. This mountain, especially here, these are so blurry. There are trees here, but we are not able to do any details. Even when we look at it, actually, if it was in our surroundings, this would have been blurry.
For this, it's an aerial perspective. The more blurry things are, the further it gets. The closer it gets, the more we can see it in clarity.
For this... We can perceive it as being closer to us. Then we have height in field.
Objects that are lower in our field of view are perceived to be closer. See this image. Mountains are higher in our field of perception. Can you see it?
If we draw an invisible line here, an imaginary line, then this flower is lower in our field of view. And the mountain is higher. Now you can say that these trees are higher, so why don't we make it further? Because here you can even apply aerial perspective.
Right, here you get aerial perspective because you can still see the details of the leaves. You can even apply the texture gradient, we can see the texture of the leaves. So these monocular cues of depth perception, they work together, they don't work individually.
But, when it comes to identifying, because now case studies have been done, psychology you mostly have to write only one cue, unless explicitly mentioned that which other cues are there, based on marks, determine what to tell now we have binocular cues of depth perception, what are binoculars they use both eyes, so for this binocular cues of depth perception, we will use both eyes, cues that help us perceive depth using two eyes First of all, Q is Retinal Disparity. There is a distance between our eyes, that is our nose. So, the distance between our eyes and our nose, there is a little bit of disparity in what each eye sees.
What I want you to do is bring your finger to your eye, bring your thumb in front of your eye, or cover your thumb with your hand in your thumb by closing your right eye. Okay, close your right eye. Look at this thumb and cover it with your right or left hand's thumb. Now, when you open the other eye, okay? First, I closed the right eye.
When you open your right eye now and close your left eye, you'll see a difference, right? As you can see here. What was this person doing?
He was covering this building with his thumb. When he had just closed the right eye. Now, what he did was, he closed his left eye and opened his right eye.
So, due to this disparity, he started to see this building again. And since he started to see, this is your retinal disparity. And due to this, we can also say that how much is its depth.
Next, we have convergence and accommodation. Convergence. When seeing objects that are closer to us, our eyeballs converge. While seeing objects that are farther away, our eyeballs become parallel.
This convergence is taken into consideration during depth. perception example a pencil near a face causes convergence like pencil amara object again this case there's a closer object to Mari eyeballs as he Ray right the convergence a convergence kata when two lines are coming close together that is your convergence for example the happy be car a humble gamma a eyeballs can watch current order to look at the object that is close a be object Imagine that we are moving far away. Let's say to this point. So our eyeballs are parallel. Right?
It was converging here and then we went far away so it started paralleling in order to focus on the same object. So the more convergence we have, the more close the object is. The less convergence or the more our eyeballs are parallel, we can say that it is that farther away.
Next we have accommodation. While seeing objects that are closer to us, the ciliary muscles in our eye adjust the lens to be thicker and convex. While seeing objects that are farther away, the lenses flatter. Our eye basically has a lens.
That is all you need to know. And these small things of the lens are visible. It is controlled by our ciliary muscles. There are different layers in the eyes.
This is of the choroid layer. This you do not need to know. If there was biology in 10th, you already know this. Very well.
If you write it, it will work. No worries. We will not cut the max. But even if you don't, it is absolutely fine. Just remember that the ciliary muscles accommodate our lens based on the distance of the object.
So that we can focus on that object. Why do we have to focus? Because this lens refracts light.
Refraction is basically bending the light. This was basic physics. If you haven't studied physics, then still very simple to understand. Refraction, all this is not necessary to remember.
I'm just giving a reason why lens has to be adjusted. When we look at closer objects, let's say here. So our lens is thicker. As you can see, if you compare these two lenses, this is more thicker.
And when we are looking at distant objects or a far object, our lens becomes more flat. That's it. That's all you need to know. And this accommodation based on the distance of the object, this is also calculated during the perception stage. How much our lens was, this is also calculated and how much it is flat.
Example, seeing a tree in a distance causes the lens to be flatter. object lens is flatter object lens is thicker these are the depth perception of the cues now we have attributes of color just to do definitions of all these things first we have hue and wavelength the hue of a color is what helps us characterize it as red green blue etc it depends on the wavelength of the color wavelength range from 380 nanometers to 700 nanometers this is 10 standard physics spectrum chapter if you had it well and good already know now for those of you who do not know what wavelength is look at this diagram here the waves are coming right one length of this wave from this point to this point and then length of this wave from this point to this point if you compare it of course this one is greater right this is small length and this is big length So each and every light's colour has a different wavelength which is measured in nanometres. So this 380 nanometres to 700 nanometres is called the visible spectrum of light.
You don't need to remember this. But it is from 380 nanometres to 700 nanometres. This is basically your rainbow. So it starts from violet and ends at red.
Violet has the lowest wavelength. The smallest wavelength of violet and the biggest wavelength of red. Because of this, we can determine the color.
So the bigger the wavelength, it moves towards the red side of the rainbow. The smaller the wavelength, it moves towards the violet side of the rainbow. That's all you need to know. Next we have brightness.
The brightness of a color is the amount of light it gives off. A lighter color gives off more light than darker color. So this is The color of this one is giving off more light than this maroonish brown color. Then we have saturation. The saturation of a color is its vividness and vibrancy.
A saturated color is more pure while an unsaturated color looks dull. Imagine an apple. If that apple is of this color, would you rather eat it or will you eat this color apple?
Of course, you'll eat it if it is this red. Because we perceive it as more pure. For this we will prefer to eat this apple while we will say that this apple is rotten or dead or decayed if this is the color of the apple So that is basically your saturation This is the same color but its saturation level differs Here it is most vivid and vibrant and here it is most dull Next we have after images, only definitions An afterimage is an image of an object that is left on the retina for a brief amount of time even after we stop seeing it. There is a white light above, look at it, stare at it for 10 seconds.
If you can do it, I don't want you to spoil your eyes. Just look at it for 10 seconds and then look somewhere else. Look at a wall where there is no light.
You'll still see a little bit of the light. Okay, that is the afterimage that is left. Now there are two types of after images. First we have the positive after image. Positive after image is one which retains it colors, brightness etc. it lasts for a shorter time if you are on Instagram, Reels, YouTube Shorts, these will be there where they focus on a dot and then after that they show it on a white screen and then you can see the actual object this is the same one, we won't do it now but if you are interested in that, go and watch a video of that basically here, in this one, we had to focus on its nose and then when you looked at a white wall, so this The girl looks in actual color.
That is your positive afterimage. So what is this afterimage? This will retain the entire color.
You will see the skin color, you will see the black blonde hair. You will also see the color of the dress clearly. The opposite of it is the negative afterimage. Negative afterimage is one in which the colors are inverted. Red becomes green, blue becomes yellow and vice versa.
This is for longer time. If you ask the difference, this is one. Difference kaffir it lasts for a shorter time longer time is my color retain K is a color retainer the color opposite without a we based on what the opponent process theory not in syllabus But it is important to know Opponent process theory said determine kia that a key negative after image Conce color cap so when you see this a key while a object if you stare at it for a long time You have our observed image the red becomes green blue becomes yellow some of the epic here So this is its negative afterimage form.
The final part of this chapter, illusions. For each and every illusion, remember the name of who developed the illusion. What is that illusion actually?
And then finally, its diagram. It is important to do diagrams. All of them are very simple diagrams.
And it can also be used for identification. I have taken the diagrams which are used the most commonly in the papers. You guys can easily identify if I call it identification.
First of all, what are illusions? Illusions are false interpretations of the physical world by our perceptive process. False interpretations. Now we will see how false interpretations can happen. The actual truth, we are not seeing that but instead our brain gets confused and our perception makes a mistake.
That's it. First up, we have the Muller-Lyer illusion. It was developed by Franz Muller-Lyer.
This is the name of the developer. In this illusion, two lines of the same length appear to have different lengths due to an arrowhead at their ends. Now these two lines, when you see it at first, you will see that this line is shorter than this line. But actually when you measure it with a scale or something, both of these lines have the same length. The length of these two lines is exactly the same.
The only difference is that the arrowhead that is made, Those are in different orientations. That is it. And because of these orientation differences, we observe it as this is longer and this is shorter.
Even though these are the same. Next, we have the height-width illusion developed by Wilhelm Wundt. Wilhelm Wundt, if you remember, we did it in unit 1. If you remember who Wilhelm Wundt is, please comment it down. If you are a school of thought developer, please write it down.
In this illusion, two lines of the same length are taken. One is placed perpendicular to the other and it looks longer than the base. So, these two lines are actually of the same length.
Even in exam, take the scale. The length of the line, make it 5 cm. That is more than enough. It should be the same. That is all that there needs to be.
There shouldn't be any difference. Don't make this 9cm and this 3cm. It has to be of the same length.
This is also 5cm and this is also 5cm. But when we look at it, we perceive it as being longer. Which is the perpendicular line?
The base looks shorter. And the perpendicular line looks taller. Next we have the ponzo illusion.
Developed by Mario Ponzo in this illusion two lines of the same length are placed over converging lines the lines appear to be of different lengths First let's make converging lines, two converging lines are here and then same length lines again here we draw 3-6 cm lines This is exactly the same but what we think is that this line is longer than this line This illusion I have seen a lot of times it is given over rails, rail lines also converge like we saw Right, these lines are converging here, we can make a red line on top of it So imagine, this big line here and this big line here We can give that image too So do not get confused, that is still the ponzo illusion. Next we have Zollner illusion. These two are Johan-Johan. So remember, the names of these get simpler. Developed by Johan Zollner, in this illusion, parallel lines seem to be converging due to diagonals that cut them.
This is personally my favourite illusion because I still cannot wrap my head around this. First, draw parallel lines and then make cuts from different angles. when you're looking at this it looks like these two lines are converging but actually if you're measuring it with a scale or something you can see that these lines are clearly parallel okay that is your zoller illusion then the last illusion the last concept of this chapter is the pogendorf illusion it was developed by johan pogendorf in this illusion a line that goes behind a box Seem to not be connecting properly when it emerges from the other end.
Now look at this diagram. The line in this, when we observe it, we will feel that it will follow the blue line. When the black line goes behind the rectangle, we will feel that it is actually a part of the blue line.
But in reality, the black is connecting with the red, not blue. Now this disparity is an illusion. It is our perceptual error. So when you draw this, first make a rectangle, keep a scale straight, first draw this line, black and red, and then an extra line, blue. That's it.
So you'll be able to draw this diagram as well. So this was your Pogindorf Illusion. And that is it for this video. This chapter is very short, very interesting, very easy, very scoring.
It basically has only definitions, no big theories. I can almost guarantee laws of grouping will come and at least one illusion will come. Most 99% of the papers that I've seen have these two questions. So prepare these two the best.
And at least monocular cues and binocular cues are also asked. Now if you have seen the recent specimen paper of psychology, it has become very case study based. So be ready. for identifying things.
This chapter is very visual. You need to be familiar with all concepts. They will let you identify anything. Not just illusions. Which binocular is being used?
Which monocular is being used? Which constancy is being shown here? Which law of grouping is there? Figure in ground principle. Which type of factor is used in this specific case study?
You can give all this and you have to be ready for all of this. So this chapter is very interesting especially when it comes to reading. So I wish you all the best for your exams. If you have any doubts, please drop them down in the comments. Thank you.
Bye-bye. How many passes did you count? The correct answer is 15 passes.
But did you see the gorilla?