Understanding Sensation and Perception in Psychology

Good morning, evening, afternoon, night, whenever you're watching this, welcome back to the Mr. Sin channel. Today we're going to be going over all of unit three of AP Psychology, Sensation and Perception. Now just like the last two unit review videos, make sure you go and get the study guide that goes along with this video. You can find the study guide in my ultimate review packet, which not only has a study guide for this video, but it also has unit review videos for all of the units of AP Psychology, plus answer keys, practice quizzes, and full exams, and more. It's a great resource that'll definitely... definitely help you get an A in your class and a five on that national exam. All right, now that you got your study guide out and you're ready to go, let's start talking about the difference between sensation and perception. Remember, sensation is raw data, information that we receive from our five senses. The sources are sensory receptors. While perception is the process of interpreting the information we've obtained through our five senses. We can organize our sensations and perception in a variety of different ways. Going back to Gestalt psychology, we can see a focus on perceptual organization. If you remember from our Unit 1 videos, Gestalt psychology believes that the whole is greater than individual parts. Gestalt principles believe that people will perceive objects in their simplest form, and that human beings will instinctively or naturally follow certain lines and curves. Gestalt's principles can be broken down into figure and ground, continuation, closure, similarity, proximity, and symmetry. In order to keep these review videos short and make sure that you can maximize your study time, I'm only going to briefly overview the different Gestalt psychology principles. Principle. If you need more information on any of these principles go check out my topic review video on YouTube. It goes into a lot more detail on all the different principles. Also right now make sure you pause the video and complete the table in your study guide. Once you're done, unpause the video and we'll go over the answer. Figuring ground is the tendency of our visual system to simplify what we see into two categories. Figures, which are objects we are focusing on or interested in, and ground, which is everything else that falls into the background. This allows us to quickly simplify information and identify important information. The continuation principle looks at how we view an object. We will continue to view the entire object and continue over to the next one. For example, when looking at the design of an exit sign, we can see that the arrow points outwards, leading someone who is reading the sign to continue their gaze to extend towards the exit. The closure principle is the idea that our brain will subconsciously fill in missing information when looking at a familiar object that is incomplete. For example, when looking at this image of black lines and shapes, you can probably see an airplane, even though this image is incomplete. Similarity is why when we are viewing objects in a group or specific pattern it looks like one object even though the group or the pattern is separate. This also happens when there is an anomaly. When objects are similar except for one object, that object becomes the focal point and it stands out from the rest. Proximity is what creates a singular image out of objects that are placed close to each other, while the objects that are placed further apart will seem as separate. Lastly, there is symmetry, which is when objects that are symmetrical to each other are perceived as one object. object. Whenever we are perceiving different images or situations, we use these six Gestalt principles to help us form our perception of the different sensations we are perceiving. Another key component of our visual field is depth perception, which is the ability to perceive relative distance of an object in one's visual field. In order for us to be able to perceive distance or depth, we use binocular cues and monocular cues. Binocular cues require two eyes. When the objects we are viewing are near us, our eyes actually move inward. And when the objects we are... are looking at are farther away, our eyes will straighten. This is known as convergence. We can see that when we are looking at an object, each eye is seeing a different part of the object. This is what allows us to have a degree of depth. That is also known as retinal disparity. Monocular cues, on the other hand, require only one eye. Monocular cues can be broken up into six different cues. Relative size allows us to determine how close an object is to us. Objects that are closer to us will appear larger than objects that are farther away, which will appear smaller. Interposition also helps us understand how how close an object is. We can see that when objects are blocked by another object, they're most likely farther away, while objects that are not obstructed are closer. Objects that are higher appear to also be farther away compared to objects that are lower. They appear to be closer to us. This is a relative height cue. Shading and contour help us understand the form of an object. Parts of the object are hazy and appear to have less detail. They're often farther away from us. And objects that are more clear and in focus are closer. Texture and gradient also help us with depth perception. Objects that are are clear and in focus and full of detail are appear closer to us than objects that are further away and are blurry. Lastly, we can also look at linear perspective, which is when parallel lines converge at the point in the distance. This helps us understand our positioning and understands depth. One other monocular cue is the motion parallax. This deals with motion. Objects that are closer to you will appear to be moving quickly, while things that are farther away from you will appear to be moving slowly. Just one of the reasons why when you're looking out of a car window, the cars next to you appear to be going. going so fast, but the landscape and the distance or the clouds above are slowly moving. Before we finish up with the first part of unit 3, I want to also remind you to check the answer key in the ultimate review packet for more examples and information on the monocular cues and gestalt principle. Whenever you are taking in an outside stimulus through one of your senses, you activate your sensory neurons, which end up creating a sensation for you. This is known as sensory transduction. But in order for you to experience a sensation, you need to hit the absolute threshold, which is the minimum amount of a stimulation needed to... experience a stimulus. When trying to understand if you would notice a stimulus, we can look at the signal detection theory, which predicts if you will perceive a weak signal or a stimulus that is near the absolute threshold. For example, let's say I was flashing a subscribe text throughout this entire unit review video in order to remind you to subscribe and support the channel so you don't miss out on future videos. If you notice the subscribe text when it appeared on the screen, and when I told you about it, we could see it was a hit. The signal was present and you were aware of it. If when I mentioned the subscribe text, you couldn't remember seeing it. it and it did happen then it was a miss and the signal was below your threshold. Now if I never had a subscribe text appear on the screen and you said you saw one anyways well we can see that we have a false alarm. And lastly if there never was a subscribe text on the screen and you never thought that there was then we can see that there was a correct rejection. Now sometimes we may miss a stimulus because we have experienced sensory adaptation which is different from habituation. Sensory adaptation happens when we have a stimulus that is continuous it doesn't change. For example, if you light a candle in a room, at first you can smell it, but as the day goes on, eventually you'll no longer be able to smell the candle. But if someone else comes into the room, they'll probably be able to smell it right away. Habituation, on the other hand, is when you are repeatedly exposed to a stimulus and start to have a reduced response to the stimulus. For example, the first time a person does drugs, they may get a strong reaction from the drug. But if they continue to use the drug, they will need to take more and more of the drug to feel the same effect. Remember, with habituation, you are learning from a repeated stimulus which then results in a decrease in your responsiveness to the stimulus. And with sensory adaptation you are getting used to an unchanging stimulus. Another concept that you want to be familiar with when it comes to detecting changes in a stimuli is the difference threshold. This is the minimum change between two stimuli that causes an individual to detect the change. For example if you turn the sound up in your car or on your computer can you tell the difference between each of the different volumes? At what point can you no longer tell the difference? I bet you could tell the difference between... volume five, six, and seven, but could you tell the difference between volume 65, 66, and 67? As the volume is increasing, it almost becomes harder to understand the difference between each individual volume chain. To best understand the difference threshold, we can look at Weber-Fechner's law. This is the idea that for us to notice a difference between two stimuli, the two stimuli must differ by a constant percent, not a constant amount. For example, if I drop one drop of water in an empty glass, you'll be able to tell that there's one drop of water in that glass, but if But if I have a glass that's half full and I add one more drop of water, you won't be able to tell that the glass is anymore full. Now in section two of unit three, we explore the different principles of perception. To start, let's talk about perceptual constancy, which is when you perceive objects and stimuli with familiar standard shape, size, color, and lightness, even when changes are occurring. Size constancy is the tendency of the brain to perceive objects as the same size, while color constancy is when our perception of a color of an object remains the same, even if the lighting is different. changes. Shape constancy is the tendency of the brain to perceive an object to have the same shape even when it's moving. For example, if you open or close a door, the door will remain the same shape in your mind. Lightness constancy is the perception of blackness, whiteness, and grayness of an object. Essentially, it's the shading of the object. We can see that when we are perceiving information, our perceptual sets influence certain aspects of images, objects, or the situations that we are perceiving. This leads us to focus on certain aspects and ignore others depending on what our perceptual set is. For example, individuals who work with numbers for a living are more likely to quickly identify numbers in images, while individuals who read more books or do more with words are more likely to identify words or letters first. Throughout our lives, we experience different situations and experiences that allow us to build schemas. This helps us organize our information and perceive the world around us. A schema is a cognitive framework that is based on an individual's experiences. They help guide their perceptual sets and organize the world around them. For example, if someone was to ask you what you're going to do at a family birthday party next week, you probably would be able to describe to them the general activities that would happen at the party, even though it hasn't happened yet. You have been to a birthday party before and you've already created a schema for birthday parties. Schemas and perceptual sets can help us quickly organize information and understand the world around us. However, sometimes they can also lead us astray. For example, even something as simple as our emotional state can influence how we perceive the world around us. If we're in a good mood, we're more likely to focus on positive. aspects in life and also Positive thought or if we're in a bad mood We're more likely to focus on the negative things and dismiss the positive one or depending on how you were raised you might be more Or less inclined to perceive certain information or situation for example if you were raised in an urban area in a western country You're more likely to see right since they are more common in your society. This is one of the reasons why optical illusions such as the Muller-Lyer illusion work. This illusion has multiple lines or arrows that are the same length, but for many people, they perceive this illusion to have lines that are different lengths. Depending on your perception, conceptual sets, you may be more or less likely to fall for this illusion. Now section three of unit three is all about your eyes, but before we go into the different parts of the eye, if you're finding any value in this review video, consider subscribing and sharing the video. It's a great way to support the channel and it also makes sure that you don't miss out on any future unit review video. All right, now starting out with the outside layer of the eye, we have the sclera. This white fibrous tissue protects the eye and forms the substance of the eye. Next, we have the cornea, which is transparent and protects the eye. The cornea allows for light to bend. If this is irregularly shaped, it could impact a person's ability to focus. The aqueous humor, which is made up of water and salt, helps maintain pressure within the eye and provides nourishment to the cornea and the lens. The iris is a ring-shaped membrane located behind the cornea. This determines a person's eye color and controls how much light enters the eye. It does this by contracting and relaxing two muscles that surround the pupil. Speaking of the pupil, this is the dark part of your eye. It's located between the iris and is where light passes through upon entering the eye. the eye. Behind the pupil and the iris is the lens. This allows for the eye to change focus. The lens is biconvex, which means it's curved on both ends. Next we have the vitreous humor. This clear gel-like fluid is in the vitreous cavity located between the lens and the retina. It gives the eye its support and also shape. Speaking of the retina, this is located in the back of the eye and is made up of layers of light sensitive cells known as photoreceptors. These convert the light into neural impulses that allow for the brain to process what the eye is seeing. Now the Choroid helps support the the retinal cells and other cells in the eye by providing oxygen and nutrients from the blood vessel. Lastly, there's the optic nerve, which is located in the back of the eye. It's made up of the retinal ganglion axon. Neural impulses travel in the optic nerve from the eye to briefly stop at the thalamus and then travel to the primary visual cortex, where information will be processed in the occipital lobe. Now also located in the eye are rods and cones. Rods are located on the outer edge of the retina and cones are located in small depressions known as the fovea centralis. Cones are would allow you to see fine details and allow for clear vision and help you see color. While rods are visual receptors that allow you to see in dim light but don't provide any color information. Since we're on the topic of vision, you'll also want to understand the difference between astigmatism and cataracts. Astigmatism occurs if the cornea is irregularly shaped and it could impact a person's ability to focus. While cataracts happens when the lens of your eye becomes cloudy, causing vision to become blurry. If we move our conversation into the wonderful world of colors, we can see the two-stage theory, which tries to explain how we perceive color. The first part of the theory is the trichromatic theory, which states that individuals are able to see color because of different wavelengths of light that stimulate the combinations of three different color receptors. Photo receptors work in teams of three, red, green, and blue. Next is the opponent processing theory, which complements the trichromatic theory. This theory states that the information that is received from the cones is sent to the ganglion cells. This causes some neurons to become excited and others inhibited. We all have three color pairings, red, green. blue, yellow, and black, white. That was a really quick overview of those two theories. If you need more information about those or any parts of the eye, make sure you go check out my Unit 3, Topic 3 video on YouTube. Now, when looking at colors, we can see that cooler colors have a shorter wavelength and warmer colors have a longer wavelength. Some people are not able to see different colors. This is known as color blindness. People who have achromatism will only be able to see black, white, and gray because they lack retinal cone, while individuals who only possess two of the three types of retinal. cones may have dichromatism, which leads an individual to become confused between certain colors. The most common type is red-green color blindness. Lastly, if an individual is able to see all of the colors, they have trichromatism. One last concept I want to review is synesthesia. This is a neurological condition where one of an individual's senses is stimulated, and it results in stimulating another sense at the same time. For example, if you're listening to this video and have synesthesia, you may be hearing me talk and seeing a color for every word I say. So for 3.4, we're going to be talking about our perceptions and how we perceive different objects, sounds, and experiences. We can see that when we encounter different stimuli, we use top-down processing, which is when you use prior knowledge and previous information to help interpret the information you are perceiving. When we use top-down processing, the stimuli we are taking in often is not that complicated, and we're pretty familiar with it. But if the stimuli is information that is complex and not familiar to you, you'll most likely be using bottom-up processing, when we interpret information that is complex and unfamiliar. You process the information as it's incoming and you organize it as you take it in. When we use top-down processing we use our prior knowledge to evaluate the new information or situation. This can lead us to have skewed perceptions since our top-down processing can influence our perception. For example, what do you see in this picture? Do you see a bird flying through the air? Or do you see a bunny on skis? Did the image change as I asked these questions? I gave you more information that could have influenced your processing. Once I said the bird or the bunny, you may have started to pro- process the picture with that knowledge I gave you. To help you better understand this, think about trying to complete a large puzzle. If you never saw the box or a picture of the puzzle and you tried to examine each individual piece and put them together without any assistance, this would be bottom-up processing. However, if you look at the picture of the box and you have an idea of what the puzzle should look like, and you may then start to organize the pieces in a manner that makes it easier to complete the picture, or if you've done a puzzle before and maybe you use your previous knowledge of puzzles to start by compiling the picture, completing the outer edges of the puzzle, that would be an example of top-down processing. We can see that when we use top-down processing, it impacts our ability to even proofread our own paper. This is known as proofreader's illusion. This happens because as you read the paper you wrote, you know what you intended to write. So your brain will often skip over spelling or grammar errors because it knows what you intended to write. This is why it's always good to read a paper out loud or have someone else look at it. Moving into section five of unit three, we can see we have our auditory sensation and perception. Starting out with the ear, we first have the pinna, which is the outer part of the ear. It's made up of cartilage and helps direct sound into the ear. Once sound enters the ear, it is in the auditory canal. This is the entrance to the ear. This tube funnels sound into the ear from the pinna into the eardrum. As sound moves down the auditory canal, it vibrates and causes the eardrum to vibrate, which transform the sound vibrations into mechanical vibrations of the bones of the middle ear. These bones are known as the ossellous bones. There is the malleus, which is also called the hammer. This the incus, which is also known as the anvil, and the stapes, which is also known as the stirrup. All these bones help with amplifying sounds sent in from the eardrum to the inner ear. Next is the oval window, which is located in the opening of the wall of the cochlea. It's covered with a membrane that helps with the amplification of sounds and sends waves into the inner ear. The cochlea is one of the first structures in the inner ear. This structure is filled with a fluid and has three canals. The organ of Corti contains sensory receptors that help with hearing. The organ of Corti sits on the on the basilar membrane. When the vibrations come into the inner ear, the basilar membrane will vibrate and a wave-like ripple, which leads to the movement of the stereocilia, which starts the process of converting vibrations into electrical impulses. Lastly, there is the semicircular canals, which are located above the cochlea and are filled with fluid. This helps balance. When an individual tips their head, fluids shift, causing the nerves to become stimulated, which sends signals to the brain about a person's movement and head position. Now one of the parts of the ear that I'm was the stereocilia. Remember, these are tiny hairs that protrude from the hair cells of the organ of Corti along the basilar membrane. When the stereocilia start to vibrate, it starts the process of converting the vibrations in the ear into electrical impulses to send them to the brain. And since we've been talking about sound, we also need to review the difference between a sound's frequency and amplitude. The frequency of a sound wave is what will determine the pitch. This is the sound's highness or lowness. The shorter the wave, the higher the pitch will be. Amplitude on the other. hand is the strength of a sound wave found by taking the distance from the peak or the trough of the wave and measuring it from the equilibrium when looking at sound waves we can see that theory such as the place theory state that certain hair cells respond to certain frequency hair cells that are located at the base of the cochlea can detect higher pitch sound while hair cells near the top of the cochlea can detect lower pitch sounds with the hair cells at the very top near the spiral detecting the lowest pitch sound now the last part of this section of unit 3 deals with hearing loss if an individual sees a decline in the clarity, loudness, and range of sounds and are no longer able to hear as they once did, it could indicate that the cilia and the auditory nerve may have been damaged. This type of hearing loss is known as sensorineural hearing loss. Whereas individuals with conductive hearing loss have something blocking sound from moving through the outer ear to the middle and inner ear. This can be because of something blocking the outer ear or because the ear was damaged and can no longer have sound travel through the auditory canal. If individuals are experiencing hearing loss, they may have a problem with the auditory hearing loss, they can get a cochlear implant, which is a device that converts sound into electrical signals. These signals help stimulate the auditory nerve and allow for the signal to be sent to the brain. Or an individual can get a hearing aid, which amplifies the sound to allow an individual to hear different sounds around them. Changing gears and moving away from the ear over to our nose and mouth, we can see that this section of unit three is all about our chemical senses. Starting out with the nose, we can see that when we breathe in through the nasal cavity, odors enter the nasal cavity and go back to the olfactory epithelium, which is a ...membrous tissue that contains olfactory receptor cells. This helps with the sense of smell. Olfactory receptor cells are a patch of skin that has receptor cells. These neurons are what allow an individual to smell. Next, located above the cribriform plate, we have the olfactory... bulb, which is where transduction of smell occurs. Electrical signals are then sent through the olfactory nerve, where they are sent to the amygdala, and then to the hippocampus in the brain. The last part of this section in Unit 3 is all about your tongue and taste. Remember, when talking about taste, we are talking about gestation, which is the sensation of tasting. Located on your tongue are the papillae. These small structures are more commonly known as taste buds. There are four different types of papillae that allow you to experience the five basic tastes, sweet, salty, sour, bitter, and savory. Lastly, when you eat something, molecules enter your taste buds and stimulate the cells. Once the stimulation occurs, signals are sent through the facial nerve to the thalamus in the brain. Then the signals are sent to the temporal lobe of the cerebral cortex. Congratulations, you made it to the last section of unit three. We'll see you in the next. This section is all about your body and senses. The skin is one of the largest organs of the body. The outside layer of your skin is the epidermis. This creates a barrier to protect a person from foreign pathogens and gives an individual their skin color. Below the epidermis is the dermis, which consists of two different layers. This is a connective tissue and it's where your blood vessels and nerve endings are located. This is also where you get your sense of touch and pain from. Located in the dermis is an individual's nociceptors. These are pain receptors. These sensory receptors are what detect painful stimuli, temperatures, pressures, or chemicals. Lastly, underneath the dermis is the hypodermis, which really isn't a layer of skin, rather it's a layer of fat that helps insulate an individual's tissue and absorb shock. And since I mentioned pain when talking about the layers of the skin, I also want to quickly touch on phantom limb sensation. This occurs with individuals who have lost a body part. Phantom limb sensation is when individuals experience pain where the body part they lost used to be. Now the last part of section seven is kinesthesis, which is the perception of the position and movement of... individual body parts. One of the ways in which the brain understands what is happening with our bodies is by using information from our proprioceptors. These are sensory receptors that are located in various muscles and tendons. They allow for the brain to get a better sense of the position and movement of our limbs. Another way in which the brain can gain insight into our movement is with vestibular sense. This is our ability to maintain our balance. This occurs when our head moves, causing fluid in the vestibular canals of our inner ear to shift. We can see our bodies are complex, and even though our individual senses are complex, we can still senses are quite amazing, it is when they come together and interact with one another that we truly experience the world around us. When our senses interact with one another and influence each other, it's known as sensory interaction. This is what allows us to truly experience the world in which we live. Congratulations, you just completed another unit review of AP Psychology. Now you need to go take the practice quiz in the Ultimate Review Packet and check the answers in the study guide. Also too, don't forget to check out all the other awesome resources in the packet that will help you with all the other units of AP Psychology. of AP Psychology. As always, if you found value in this video, consider subscribing to the channel. Thank you so much for watching. I'm Mr. Sin, and I'll see you next time online.

You can find the study guide in my ultimate review packet, which not only has a study guide for this video, but it also has unit review videos for all of the units of AP Psychology, plus answer keys, practice quizzes, and full exams, and more. It's a great resource that'll definitely... definitely help you get an A in your class and a five on that national exam. All right, now that you got your study guide out and you're ready to go, let's start talking about the difference between sensation and perception. Remember, sensation is raw data, information that we receive from our five senses.

The sources are sensory receptors. While perception is the process of interpreting the information we've obtained through our five senses. We can organize our sensations and perception in a variety of different ways.

Going back to Gestalt psychology, we can see a focus on perceptual organization. If you remember from our Unit 1 videos, Gestalt psychology believes that the whole is greater than individual parts. Gestalt principles believe that people will perceive objects in their simplest form, and that human beings will instinctively or naturally follow certain lines and curves. Gestalt's principles can be broken down into figure and ground, continuation, closure, similarity, proximity, and symmetry. In order to keep these review videos short and make sure that you can maximize your study time, I'm only going to briefly overview the different Gestalt psychology principles.

Principle. If you need more information on any of these principles go check out my topic review video on YouTube. It goes into a lot more detail on all the different principles. Also right now make sure you pause the video and complete the table in your study guide.

Once you're done, unpause the video and we'll go over the answer. Figuring ground is the tendency of our visual system to simplify what we see into two categories. Figures, which are objects we are focusing on or interested in, and ground, which is everything else that falls into the background.

This allows us to quickly simplify information and identify important information. The continuation principle looks at how we view an object. We will continue to view the entire object and continue over to the next one. For example, when looking at the design of an exit sign, we can see that the arrow points outwards, leading someone who is reading the sign to continue their gaze to extend towards the exit.

The closure principle is the idea that our brain will subconsciously fill in missing information when looking at a familiar object that is incomplete. For example, when looking at this image of black lines and shapes, you can probably see an airplane, even though this image is incomplete. Similarity is why when we are viewing objects in a group or specific pattern it looks like one object even though the group or the pattern is separate.

This also happens when there is an anomaly. When objects are similar except for one object, that object becomes the focal point and it stands out from the rest. Proximity is what creates a singular image out of objects that are placed close to each other, while the objects that are placed further apart will seem as separate.

Lastly, there is symmetry, which is when objects that are symmetrical to each other are perceived as one object. object. Whenever we are perceiving different images or situations, we use these six Gestalt principles to help us form our perception of the different sensations we are perceiving. Another key component of our visual field is depth perception, which is the ability to perceive relative distance of an object in one's visual field. In order for us to be able to perceive distance or depth, we use binocular cues and monocular cues.

Binocular cues require two eyes. When the objects we are viewing are near us, our eyes actually move inward. And when the objects we are...

are looking at are farther away, our eyes will straighten. This is known as convergence. We can see that when we are looking at an object, each eye is seeing a different part of the object.

This is what allows us to have a degree of depth. That is also known as retinal disparity. Monocular cues, on the other hand, require only one eye.

Monocular cues can be broken up into six different cues. Relative size allows us to determine how close an object is to us. Objects that are closer to us will appear larger than objects that are farther away, which will appear smaller.

Interposition also helps us understand how how close an object is. We can see that when objects are blocked by another object, they're most likely farther away, while objects that are not obstructed are closer. Objects that are higher appear to also be farther away compared to objects that are lower.

They appear to be closer to us. This is a relative height cue. Shading and contour help us understand the form of an object. Parts of the object are hazy and appear to have less detail. They're often farther away from us.

And objects that are more clear and in focus are closer. Texture and gradient also help us with depth perception. Objects that are are clear and in focus and full of detail are appear closer to us than objects that are further away and are blurry.

Lastly, we can also look at linear perspective, which is when parallel lines converge at the point in the distance. This helps us understand our positioning and understands depth. One other monocular cue is the motion parallax. This deals with motion.

Objects that are closer to you will appear to be moving quickly, while things that are farther away from you will appear to be moving slowly. Just one of the reasons why when you're looking out of a car window, the cars next to you appear to be going. going so fast, but the landscape and the distance or the clouds above are slowly moving.

Before we finish up with the first part of unit 3, I want to also remind you to check the answer key in the ultimate review packet for more examples and information on the monocular cues and gestalt principle. Whenever you are taking in an outside stimulus through one of your senses, you activate your sensory neurons, which end up creating a sensation for you. This is known as sensory transduction.

But in order for you to experience a sensation, you need to hit the absolute threshold, which is the minimum amount of a stimulation needed to... experience a stimulus. When trying to understand if you would notice a stimulus, we can look at the signal detection theory, which predicts if you will perceive a weak signal or a stimulus that is near the absolute threshold.

For example, let's say I was flashing a subscribe text throughout this entire unit review video in order to remind you to subscribe and support the channel so you don't miss out on future videos. If you notice the subscribe text when it appeared on the screen, and when I told you about it, we could see it was a hit. The signal was present and you were aware of it. If when I mentioned the subscribe text, you couldn't remember seeing it. it and it did happen then it was a miss and the signal was below your threshold.

Now if I never had a subscribe text appear on the screen and you said you saw one anyways well we can see that we have a false alarm. And lastly if there never was a subscribe text on the screen and you never thought that there was then we can see that there was a correct rejection. Now sometimes we may miss a stimulus because we have experienced sensory adaptation which is different from habituation.

Sensory adaptation happens when we have a stimulus that is continuous it doesn't change. For example, if you light a candle in a room, at first you can smell it, but as the day goes on, eventually you'll no longer be able to smell the candle. But if someone else comes into the room, they'll probably be able to smell it right away.

Habituation, on the other hand, is when you are repeatedly exposed to a stimulus and start to have a reduced response to the stimulus. For example, the first time a person does drugs, they may get a strong reaction from the drug. But if they continue to use the drug, they will need to take more and more of the drug to feel the same effect.

Remember, with habituation, you are learning from a repeated stimulus which then results in a decrease in your responsiveness to the stimulus. And with sensory adaptation you are getting used to an unchanging stimulus. Another concept that you want to be familiar with when it comes to detecting changes in a stimuli is the difference threshold.

This is the minimum change between two stimuli that causes an individual to detect the change. For example if you turn the sound up in your car or on your computer can you tell the difference between each of the different volumes? At what point can you no longer tell the difference? I bet you could tell the difference between...

volume five, six, and seven, but could you tell the difference between volume 65, 66, and 67? As the volume is increasing, it almost becomes harder to understand the difference between each individual volume chain. To best understand the difference threshold, we can look at Weber-Fechner's law. This is the idea that for us to notice a difference between two stimuli, the two stimuli must differ by a constant percent, not a constant amount. For example, if I drop one drop of water in an empty glass, you'll be able to tell that there's one drop of water in that glass, but if But if I have a glass that's half full and I add one more drop of water, you won't be able to tell that the glass is anymore full.

Now in section two of unit three, we explore the different principles of perception. To start, let's talk about perceptual constancy, which is when you perceive objects and stimuli with familiar standard shape, size, color, and lightness, even when changes are occurring. Size constancy is the tendency of the brain to perceive objects as the same size, while color constancy is when our perception of a color of an object remains the same, even if the lighting is different.

changes. Shape constancy is the tendency of the brain to perceive an object to have the same shape even when it's moving. For example, if you open or close a door, the door will remain the same shape in your mind. Lightness constancy is the perception of blackness, whiteness, and grayness of an object.

Essentially, it's the shading of the object. We can see that when we are perceiving information, our perceptual sets influence certain aspects of images, objects, or the situations that we are perceiving. This leads us to focus on certain aspects and ignore others depending on what our perceptual set is.

For example, individuals who work with numbers for a living are more likely to quickly identify numbers in images, while individuals who read more books or do more with words are more likely to identify words or letters first. Throughout our lives, we experience different situations and experiences that allow us to build schemas. This helps us organize our information and perceive the world around us.

A schema is a cognitive framework that is based on an individual's experiences. They help guide their perceptual sets and organize the world around them. For example, if someone was to ask you what you're going to do at a family birthday party next week, you probably would be able to describe to them the general activities that would happen at the party, even though it hasn't happened yet.

You have been to a birthday party before and you've already created a schema for birthday parties. Schemas and perceptual sets can help us quickly organize information and understand the world around us. However, sometimes they can also lead us astray.

For example, even something as simple as our emotional state can influence how we perceive the world around us. If we're in a good mood, we're more likely to focus on positive. aspects in life and also Positive thought or if we're in a bad mood We're more likely to focus on the negative things and dismiss the positive one or depending on how you were raised you might be more Or less inclined to perceive certain information or situation for example if you were raised in an urban area in a western country You're more likely to see right since they are more common in your society.

This is one of the reasons why optical illusions such as the Muller-Lyer illusion work. This illusion has multiple lines or arrows that are the same length, but for many people, they perceive this illusion to have lines that are different lengths. Depending on your perception, conceptual sets, you may be more or less likely to fall for this illusion. Now section three of unit three is all about your eyes, but before we go into the different parts of the eye, if you're finding any value in this review video, consider subscribing and sharing the video.

It's a great way to support the channel and it also makes sure that you don't miss out on any future unit review video. All right, now starting out with the outside layer of the eye, we have the sclera. This white fibrous tissue protects the eye and forms the substance of the eye.

Next, we have the cornea, which is transparent and protects the eye. The cornea allows for light to bend. If this is irregularly shaped, it could impact a person's ability to focus. The aqueous humor, which is made up of water and salt, helps maintain pressure within the eye and provides nourishment to the cornea and the lens. The iris is a ring-shaped membrane located behind the cornea.

This determines a person's eye color and controls how much light enters the eye. It does this by contracting and relaxing two muscles that surround the pupil. Speaking of the pupil, this is the dark part of your eye.

It's located between the iris and is where light passes through upon entering the eye. the eye. Behind the pupil and the iris is the lens.

This allows for the eye to change focus. The lens is biconvex, which means it's curved on both ends. Next we have the vitreous humor. This clear gel-like fluid is in the vitreous cavity located between the lens and the retina.

It gives the eye its support and also shape. Speaking of the retina, this is located in the back of the eye and is made up of layers of light sensitive cells known as photoreceptors. These convert the light into neural impulses that allow for the brain to process what the eye is seeing.

Now the Choroid helps support the the retinal cells and other cells in the eye by providing oxygen and nutrients from the blood vessel. Lastly, there's the optic nerve, which is located in the back of the eye. It's made up of the retinal ganglion axon. Neural impulses travel in the optic nerve from the eye to briefly stop at the thalamus and then travel to the primary visual cortex, where information will be processed in the occipital lobe.

Now also located in the eye are rods and cones. Rods are located on the outer edge of the retina and cones are located in small depressions known as the fovea centralis. Cones are would allow you to see fine details and allow for clear vision and help you see color.

While rods are visual receptors that allow you to see in dim light but don't provide any color information. Since we're on the topic of vision, you'll also want to understand the difference between astigmatism and cataracts. Astigmatism occurs if the cornea is irregularly shaped and it could impact a person's ability to focus. While cataracts happens when the lens of your eye becomes cloudy, causing vision to become blurry.

If we move our conversation into the wonderful world of colors, we can see the two-stage theory, which tries to explain how we perceive color. The first part of the theory is the trichromatic theory, which states that individuals are able to see color because of different wavelengths of light that stimulate the combinations of three different color receptors. Photo receptors work in teams of three, red, green, and blue.

Next is the opponent processing theory, which complements the trichromatic theory. This theory states that the information that is received from the cones is sent to the ganglion cells. This causes some neurons to become excited and others inhibited.

We all have three color pairings, red, green. blue, yellow, and black, white. That was a really quick overview of those two theories.

If you need more information about those or any parts of the eye, make sure you go check out my Unit 3, Topic 3 video on YouTube. Now, when looking at colors, we can see that cooler colors have a shorter wavelength and warmer colors have a longer wavelength. Some people are not able to see different colors.

This is known as color blindness. People who have achromatism will only be able to see black, white, and gray because they lack retinal cone, while individuals who only possess two of the three types of retinal. cones may have dichromatism, which leads an individual to become confused between certain colors.

The most common type is red-green color blindness. Lastly, if an individual is able to see all of the colors, they have trichromatism. One last concept I want to review is synesthesia.

This is a neurological condition where one of an individual's senses is stimulated, and it results in stimulating another sense at the same time. For example, if you're listening to this video and have synesthesia, you may be hearing me talk and seeing a color for every word I say. So for 3.4, we're going to be talking about our perceptions and how we perceive different objects, sounds, and experiences. We can see that when we encounter different stimuli, we use top-down processing, which is when you use prior knowledge and previous information to help interpret the information you are perceiving.

When we use top-down processing, the stimuli we are taking in often is not that complicated, and we're pretty familiar with it. But if the stimuli is information that is complex and not familiar to you, you'll most likely be using bottom-up processing, when we interpret information that is complex and unfamiliar. You process the information as it's incoming and you organize it as you take it in.

When we use top-down processing we use our prior knowledge to evaluate the new information or situation. This can lead us to have skewed perceptions since our top-down processing can influence our perception. For example, what do you see in this picture?

Do you see a bird flying through the air? Or do you see a bunny on skis? Did the image change as I asked these questions?

I gave you more information that could have influenced your processing. Once I said the bird or the bunny, you may have started to pro- process the picture with that knowledge I gave you. To help you better understand this, think about trying to complete a large puzzle. If you never saw the box or a picture of the puzzle and you tried to examine each individual piece and put them together without any assistance, this would be bottom-up processing. However, if you look at the picture of the box and you have an idea of what the puzzle should look like, and you may then start to organize the pieces in a manner that makes it easier to complete the picture, or if you've done a puzzle before and maybe you use your previous knowledge of puzzles to start by compiling the picture, completing the outer edges of the puzzle, that would be an example of top-down processing.

We can see that when we use top-down processing, it impacts our ability to even proofread our own paper. This is known as proofreader's illusion. This happens because as you read the paper you wrote, you know what you intended to write. So your brain will often skip over spelling or grammar errors because it knows what you intended to write.

This is why it's always good to read a paper out loud or have someone else look at it. Moving into section five of unit three, we can see we have our auditory sensation and perception. Starting out with the ear, we first have the pinna, which is the outer part of the ear.

It's made up of cartilage and helps direct sound into the ear. Once sound enters the ear, it is in the auditory canal. This is the entrance to the ear. This tube funnels sound into the ear from the pinna into the eardrum. As sound moves down the auditory canal, it vibrates and causes the eardrum to vibrate, which transform the sound vibrations into mechanical vibrations of the bones of the middle ear.

These bones are known as the ossellous bones. There is the malleus, which is also called the hammer. This the incus, which is also known as the anvil, and the stapes, which is also known as the stirrup.

All these bones help with amplifying sounds sent in from the eardrum to the inner ear. Next is the oval window, which is located in the opening of the wall of the cochlea. It's covered with a membrane that helps with the amplification of sounds and sends waves into the inner ear.

The cochlea is one of the first structures in the inner ear. This structure is filled with a fluid and has three canals. The organ of Corti contains sensory receptors that help with hearing.

The organ of Corti sits on the on the basilar membrane. When the vibrations come into the inner ear, the basilar membrane will vibrate and a wave-like ripple, which leads to the movement of the stereocilia, which starts the process of converting vibrations into electrical impulses. Lastly, there is the semicircular canals, which are located above the cochlea and are filled with fluid.

This helps balance. When an individual tips their head, fluids shift, causing the nerves to become stimulated, which sends signals to the brain about a person's movement and head position. Now one of the parts of the ear that I'm was the stereocilia. Remember, these are tiny hairs that protrude from the hair cells of the organ of Corti along the basilar membrane. When the stereocilia start to vibrate, it starts the process of converting the vibrations in the ear into electrical impulses to send them to the brain.

And since we've been talking about sound, we also need to review the difference between a sound's frequency and amplitude. The frequency of a sound wave is what will determine the pitch. This is the sound's highness or lowness. The shorter the wave, the higher the pitch will be. Amplitude on the other.

hand is the strength of a sound wave found by taking the distance from the peak or the trough of the wave and measuring it from the equilibrium when looking at sound waves we can see that theory such as the place theory state that certain hair cells respond to certain frequency hair cells that are located at the base of the cochlea can detect higher pitch sound while hair cells near the top of the cochlea can detect lower pitch sounds with the hair cells at the very top near the spiral detecting the lowest pitch sound now the last part of this section of unit 3 deals with hearing loss if an individual sees a decline in the clarity, loudness, and range of sounds and are no longer able to hear as they once did, it could indicate that the cilia and the auditory nerve may have been damaged. This type of hearing loss is known as sensorineural hearing loss. Whereas individuals with conductive hearing loss have something blocking sound from moving through the outer ear to the middle and inner ear. This can be because of something blocking the outer ear or because the ear was damaged and can no longer have sound travel through the auditory canal. If individuals are experiencing hearing loss, they may have a problem with the auditory hearing loss, they can get a cochlear implant, which is a device that converts sound into electrical signals.

These signals help stimulate the auditory nerve and allow for the signal to be sent to the brain. Or an individual can get a hearing aid, which amplifies the sound to allow an individual to hear different sounds around them. Changing gears and moving away from the ear over to our nose and mouth, we can see that this section of unit three is all about our chemical senses.

Starting out with the nose, we can see that when we breathe in through the nasal cavity, odors enter the nasal cavity and go back to the olfactory epithelium, which is a ...membrous tissue that contains olfactory receptor cells. This helps with the sense of smell. Olfactory receptor cells are a patch of skin that has receptor cells.

These neurons are what allow an individual to smell. Next, located above the cribriform plate, we have the olfactory... bulb, which is where transduction of smell occurs.

Electrical signals are then sent through the olfactory nerve, where they are sent to the amygdala, and then to the hippocampus in the brain. The last part of this section in Unit 3 is all about your tongue and taste. Remember, when talking about taste, we are talking about gestation, which is the sensation of tasting. Located on your tongue are the papillae. These small structures are more commonly known as taste buds.

There are four different types of papillae that allow you to experience the five basic tastes, sweet, salty, sour, bitter, and savory. Lastly, when you eat something, molecules enter your taste buds and stimulate the cells. Once the stimulation occurs, signals are sent through the facial nerve to the thalamus in the brain. Then the signals are sent to the temporal lobe of the cerebral cortex. Congratulations, you made it to the last section of unit three.

We'll see you in the next. This section is all about your body and senses. The skin is one of the largest organs of the body.

The outside layer of your skin is the epidermis. This creates a barrier to protect a person from foreign pathogens and gives an individual their skin color. Below the epidermis is the dermis, which consists of two different layers. This is a connective tissue and it's where your blood vessels and nerve endings are located. This is also where you get your sense of touch and pain from.

Located in the dermis is an individual's nociceptors. These are pain receptors. These sensory receptors are what detect painful stimuli, temperatures, pressures, or chemicals.

Lastly, underneath the dermis is the hypodermis, which really isn't a layer of skin, rather it's a layer of fat that helps insulate an individual's tissue and absorb shock. And since I mentioned pain when talking about the layers of the skin, I also want to quickly touch on phantom limb sensation. This occurs with individuals who have lost a body part.

Phantom limb sensation is when individuals experience pain where the body part they lost used to be. Now the last part of section seven is kinesthesis, which is the perception of the position and movement of... individual body parts. One of the ways in which the brain understands what is happening with our bodies is by using information from our proprioceptors. These are sensory receptors that are located in various muscles and tendons.

They allow for the brain to get a better sense of the position and movement of our limbs. Another way in which the brain can gain insight into our movement is with vestibular sense. This is our ability to maintain our balance. This occurs when our head moves, causing fluid in the vestibular canals of our inner ear to shift.

We can see our bodies are complex, and even though our individual senses are complex, we can still senses are quite amazing, it is when they come together and interact with one another that we truly experience the world around us. When our senses interact with one another and influence each other, it's known as sensory interaction. This is what allows us to truly experience the world in which we live. Congratulations, you just completed another unit review of AP Psychology. Now you need to go take the practice quiz in the Ultimate Review Packet and check the answers in the study guide.

Also too, don't forget to check out all the other awesome resources in the packet that will help you with all the other units of AP Psychology. of AP Psychology. As always, if you found value in this video, consider subscribing to the channel.

Thank you so much for watching. I'm Mr. Sin, and I'll see you next time online.

Transcript for:Understanding Sensation and Perception in Psychology

Transcript for:
Understanding Sensation and Perception in Psychology