How Our (More Than) Five Senses Work | Introduction to Psychology 6 of 30 | Study Hall

Summary

This video script explores the fascinating interplay between sensation and perception, highlighting cultural differences in color perception using the Berinmo community as an example. It delves into the biological and psychological aspects of how our senses work, from the basic cells gathering information to the brain's complex processing. The script challenges the notion of raw sensory input, revealing how our backgrounds and experiences shape our unique interpretations of the world around us, and introduces concepts like absolute threshold, subliminal messages, and sensory illusions, such as the McGurk Effect.

Takeaways

• 📚 The script is an introduction to the concept of sensation and perception in psychology, explaining how they are different yet interconnected.
• 🌈 It discusses the cultural impact on color perception, using the example of the Berinmo community in Papua New Guinea, which has a unified term 'nol' for what English speakers would distinguish as blue and green.
• 🧠 The script highlights that sensory information is processed by the brain differently, leading to varied interpretations of the same stimuli among individuals.
• 👀 The visual system is described, including how light is focused and transformed into signals by rods and cones in the eyes, which are then sent to the brain.
• 👂 The auditory system is explained, detailing how sound waves are translated into neural signals by hair cells in the inner ear and sent to the brain via the auditory nerve.
• 👃 The olfactory system's role in the sense of smell is discussed, emphasizing the interaction between odor molecules and cells in the nose, and how this leads to the production of signals sent to the brain.
• 👅 The gustatory system, responsible for the sense of taste, is described, illustrating how taste buds on the tongue respond to food molecules, creating flavors like sweet, salty, bitter, sour, or umami.
• 🖐️ The somatosensory system, including touch and proprioception, is explained, showing how the body interprets sensory information from pressure, temperature, and pain.
• 🔄 The script introduces the concepts of bottom-up and top-down processing in perception, explaining how new information is built upon sensory input and prior knowledge, respectively.
• 💡 The McGurk Effect is presented as an example of an illusion, demonstrating how the senses can conflict and affect perception, such as when visual cues alter the perception of auditory information.
• 🔍 The importance of understanding the relationship between sensation and perception is emphasized for gaining insight into human experiences and behavior.

Q & A

What is the purpose of the website gostudyhall.com mentioned in the script?

The website gostudyhall.com is mentioned as a resource for learning more about earning college credits with Study Hall courses.

Why might the experience of colors differ between individuals from different cultures?

The experience of colors can differ due to cultural knowledge and language. For example, the Berinmo community in Papua New Guinea uses a single term 'nol' for what an English speaker might call green and blue.

How does the Berinmo community's language affect their color perception compared to English speakers?

The Berinmo community's language includes a single term 'nol' for multiple shades that English speakers differentiate as green and blue. This leads to different interpretations of color, with Berinmo people often confusing shades of 'nol' in memory tests, unlike English speakers who can distinguish them.

What is the difference between sensation and perception as explained in the script?

Sensation is the process of specialized cells gathering certain information, like responding to high-frequency sound waves. Perception is the organization and processing of that sensory information by the brain, leading to an understanding or interpretation of the environment.

How does the script describe the relationship between the olfactory and gustatory systems?

The script describes the olfactory system (sense of smell) as closely related to the gustatory system (sense of taste) because the sense of smell significantly influences the sensation of taste, as evidenced by the diminished taste experience during a head cold.

What is the somatosensory system and how does it relate to the somatosensory homunculus?

The somatosensory system is responsible for interpreting sensory information from the body, such as pressure, temperature, and pain. The somatosensory homunculus is a representation in the cerebral cortex that shows the areas of the body with varying sensitivity to touch, with more sensitive areas having more space in the cortex.

What is the concept of Bottom-up processing in the context of perception?

Bottom-up processing is a type of perception where the interpretation of sensory information is built upon the actual sensory data received from the environment, such as determining the taste of a new food based on its smell and flavor.

How does Top-down processing differ from Bottom-up processing?

Top-down processing involves prior knowledge influencing the perception of new information. For instance, if someone tries a new food that reminds them of a previously disliked food, their prior experience affects their perception of the new food.

What is the 'McGurk Effect' as mentioned in the script?

The McGurk Effect is an auditory-visual illusion where the perception of one sound is influenced by the visual component of another sound, leading to the perception of a third, entirely different word.

Why is it important to study illusions like the McGurk Effect according to the script?

Studying illusions like the McGurk Effect helps researchers understand more about how our senses work and the complex processes involved in sensory perception, including how our senses do not work in isolation and how our brain interprets contradictory information.

How does the script suggest our sensory experiences can change over time?

The script implies that our sensory experiences can change over time due to various factors, including changes in our background, culture, language, and identity, which all contribute to the organization of perceptions in our brain.

Outlines

00:00

🌈 Cultural Impact on Color Perception

This paragraph explores the fascinating intersection of language, culture, and color perception. It begins by questioning whether the experience of colors is universal, using the Berinmo community in Papua New Guinea as a case study where the color categories of green and blue are merged into a single term 'nol'. This cultural difference in color naming impacts not only language but also cognitive processes, as demonstrated by memory tests where Berinmo participants confuse shades of 'nol', unlike British participants who can distinguish between green and blue. The paragraph emphasizes that sensory information is processed by the brain in ways that are influenced by individual and cultural factors, leading to diverse interpretations of the same sensory input.

05:01

👂 Sensation and Perception: How We Experience the World

The second paragraph delves into the concepts of sensation and perception, distinguishing between the two as essential components of our sensory experiences. Sensation is defined as the gathering of information by specialized cells, such as the response to sound waves in the ears, while perception is the organization and processing of that information by the brain, exemplified by recognizing a fire alarm sound and reacting accordingly. The paragraph also highlights individual differences in sensory experiences, such as the varying tastes for cilantro and the common inability to distinguish between red and green, which are attributed to biological variations. Furthermore, it introduces the idea that sensation is more biologically driven, whereas perception has a stronger psychological component, shaped by factors like background, culture, and language.

10:06

👅 The Complexity of Sensory Systems and Perception

This paragraph examines the intricacies of our sensory systems, such as the visual, auditory, olfactory, gustatory, and somatosensory systems, and how they translate external information into neural signals for the brain to process. It describes the process of transduction, where sensory information is converted into sensations and then into perceptions influenced by both biological and psychological factors. The paragraph also discusses different types of sensory processing, including bottom-up processing, which builds perception on sensory information, and top-down processing, which is influenced by prior knowledge. Additionally, it touches on the concepts of absolute threshold, subliminal messages, and sensory illusions, such as the McGurk Effect, to illustrate the complex interplay between our senses and how they shape our perception of reality.

Keywords

💡Sensation

Sensation refers to the process by which specialized cells gather certain information from the environment. In the video, it is described as what happens when cells in your ears respond to high-frequency sound waves, or when cells in your eyes interact with light. Sensation is a biological process that is the first step in how we perceive the world around us.

💡Perception

Perception is the process by which the brain organizes and interprets sensory information. The video explains that when your brain processes the sensory information from your ears and you recognize it as a fire alarm, that's perception. It's a psychological process that involves more than just the raw sensory input, incorporating our experiences and cultural background.

💡Berinmo community

The Berinmo community in Papua New Guinea is mentioned in the video as an example of how cultural knowledge can affect color perception. They use the term 'nol' to describe what English speakers would call green and blue, illustrating how different cultures can categorize and perceive colors differently.

💡Cultural knowledge

Cultural knowledge is the understanding and familiarity with the practices, beliefs, and norms of a particular society. The video uses the example of the Berinmo community to show how cultural knowledge can influence how people perceive and categorize colors, emphasizing that perception is not solely a biological process but also a product of cultural context.

💡Transduction

Transduction is the process by which sensory information is translated into signals that the brain can understand. In the video, it is mentioned as the step that occurs after sensory information reaches the brain, turning raw sensory data into something we can feel and interpret.

💡Bottom-up processing

Bottom-up processing is a type of perception where the interpretation of sensory information is built from the details of the sensory input itself. The video explains this concept by describing how the taste and smell of a new food are used to determine whether you like it, emphasizing the role of sensory details in shaping perception.

💡Top-down processing

Top-down processing is the opposite of bottom-up processing, where prior knowledge and expectations influence how new sensory information is perceived. The video uses the example of vegemite, where the similarity to another disliked salty spread affects how it is perceived, showing how prior experiences can shape perception.

💡McGurk Effect

The McGurk Effect is an auditory-visual illusion where the combination of a visual component of one sound with the auditory sound of another word leads to the perception of a third, entirely different word. The video uses this effect to illustrate how our senses can sometimes conflict and how our brain must reconcile these conflicts to make sense of the sensory input.

💡Somatic sensation

Somatic sensation, also known as the somatosensory sensation, refers to the sense of touch and the body's interpretation of sensory information from the exterior. The video discusses how this includes not only the feel of physical touch but also proprioception, which is the awareness of the body's position in space.

💡Vestibular sense

The vestibular sense is a part of the somatosensory system that helps with balance and spatial orientation. The video explains that it is responsible for our ability to hold our heads up correctly, balance when walking, and focus our eyes on moving objects, highlighting its importance in everyday movement and coordination.

💡Interoception

Interoception is the sense that allows us to gather signals from inside the body, such as heartbeats, internal temperature, or stomach rumbling. The video mentions this as an additional sense that contributes to our overall perception of the world, showing that our sensory experiences are not limited to external stimuli.

Highlights

Study Hall courses offer college credits, accessible via gostudyhall.com.

Cultural differences can affect color perception, as seen in the Berinmo community's use of 'nol' for both green and blue.

Berinmo people may confuse shades of 'nol' in memory tests, unlike English speakers who distinguish green and blue.

British participants excel in distinguishing 'nol' and 'wor' shades, not recognized in English, indicating language's impact on color perception.

Sensory information is processed by the brain, leading to varied interpretations of the world despite shared experiences.

Deja Fitzgerald introduces Study Hall: Intro to Psychology, emphasizing the subjective nature of sensory experiences.

Sensation and perception are differentiated, with sensation being the gathering of information and perception its organization and processing.

Individual biological differences, such as cilantro aversion or color blindness, affect sensory experiences.

Cultural knowledge, not just biology, influences sensory interpretation, as demonstrated by the Berinmo community's color categories.

Sensation is more biological, while perception is more psychological, though the distinction isn't clear-cut.

Sensory systems convert physical information into brain-processed signals, as illustrated by the visual and auditory systems.

The olfactory and gustatory systems are closely related, affecting how we perceive taste through smell.

The somatosensory system interprets exterior sensory information, including touch and temperature.

The somatosensory homunculus in the cerebral cortex represents the body's sensitivity to touch, with more sensitive areas receiving more brain processing power.

Interoception allows us to sense internal body processes, contributing to our overall sensory experience.

Transduction in the brain translates sensory information into felt sensations, which are then processed into perception.

Perception is influenced by a combination of biological and psychological factors, including background and culture.

Bottom-up and top-down processing describe how sensory information is used to form perceptions, with prior knowledge affecting interpretation.

Absolute threshold defines the minimum stimulus level that is detected half of the time, with subliminal messages existing below this threshold.

Illusions, such as the McGurk Effect, demonstrate the complex interplay between sensory information and perception.

Senses are not infallible and are influenced by prior experiences, culture, and identity, with sensory experiences varying between individuals.

Study Hall Intro to Psychology offers an online course for earning college credits, further exploring sensory experiences and psychology.

Transcripts

To learn more about earning college  credits with Study Hall courses go  

to gostudyhall.com or click  the link in the description.

Roses are red. Violets are blue. But is the  experience of colors the same for me and for you?

If you were raised in a culture  with English as your first language,  

calling one shade blue and another  green might seem like a no-brainer.  

But it does take brains and  cultural knowledge to do that.

See, if you were part of the Berinmo community  in Papua New Guinea, both of these colors  

would be called “nol,” a color category that  includes most of the shades that an English  

speaker like me would call green and blue –  it even covers a couple of shades of purple!

This means that two people might take  in the exact same wavelengths of light,  

but their interpretation  could be completely different.

And it’s not just a matter of  having different words for things!

When given a memory test, Berinmo people often  confused two shades of ‘nol’, while the British  

participants sailed right through the same part of  the test since they could distinguish the shades  

as green and blue. But British participants didn’t  do well on a part of the test that involved shades  

of ‘nol’ and ‘wor’ – a color distinction  that doesn’t exist in the English language.

So while our senses are an amazing  and essential part of our lives,  

they’re not a feed of raw information about  the world around us. Sensory information is  

processed by the brain, and it’s  processed differently by, well,  

different brains. And that means although we share  the same world, we each interpret it differently.

I’m Deja Fitzgerald, and this is  Study Hall: Intro to Psychology.

The information we get or don’t get from  the world around us shapes our experiences,  

from how we differentiate colors to our emotions  and reactions to events like finding out in my  

late twenties that I’m particularly good at  telling the difference between blue and green.

So as psychologists, we can learn  a lot about people when we know  

how this information actually gets  to us, which happens in two parts.

Even though we often use  these words interchangeably,  

sensation and perception  have different definitions.

Sensation is what’s happening when specialized  cells gather certain information. For example,  

if the specialized cells in your ears  respond to high-frequency sound waves,  

you’re sensing a noise in your  environment through the sense of hearing.

And perception is what’s happening when that  information is organized and processed. So  

when your brain processes the sensory  information your ears are taking in,  

and you realize it’s a fire alarm and you need  to high-tail it outta there, that’s perception!

So we all have sensory experiences that involve  sensation and perception, but they can both vary  

quite a bit from person to person. Like,  we all know someone who can't stand the  

taste of cilantro. And being unable to tell the  difference between red and green is really common.

Both of these are biological differences between  people. But like the Berinmo community shows us,  

these differences don't  have to be based in biology!

An easy way to think about how we sense the  world is that sensation is more biological  

and perception is more psychological, though  it’s not quite that black and white. But let’s  

talk about how sensation and perception work  separately before we talk about the gray area.

Though each sensory system is unique,  they all essentially do the same thing:  

change information from the physical world  into signals the brain then processes.

So if you’re visiting a friend in Hiroshima  and are about to dig into some okonomiyaki at  

a summer festival, you’re getting a bunch  of different sensory information. But all  

that information ultimately comes down  to cells sending signals to the brain.

Like when you look at your steaming  veggies-and-noodles pancake,  

you’re using the visual system, which  consists of the eyes and related parts  

of the central nervous system, like  the optic nerve and visual cortex.

Light from the world around you enters your  eyes, and different parts of them interact to  

focus the light. Then, special cells called  rods and cones turn the light into signals.  

They say the eyes are the windows to the soul,  but they’re also sort of windows for the brain.

Now take the auditory system, which consists  of the ears and parts of the nervous system  

like the auditory cortex of the brain. When your  friend tells you to dig in while the okonomiyaki  

is piping hot, cells in your inner ear, way beyond  your eardrum, called hair cells move in response  

to the sound waves made by your friend’s vocal  cords. This movement results in signals that get  

sent to our brains through a special part of  the nervous system called the auditory nerve.

We also have sensory systems that work through  interactions with molecules. That’s what’s going  

on with the olfactory system, which makes  our sense of smell possible with the nose  

and olfactory tract, a bundle of nerves that  connects to specific regions of the brain.

When you lean over your steaming food and inhale  its aroma, cells in the nose interact with odor  

molecules to produce, yup, signals that go  to the brain by way of the olfactory nerve.

And if you've ever tried eating your favorite  food when you've got a bad head cold,  

you know how important that sense of  smell is to your sensation of taste.  

That's because the olfactory system is  closely related to the gustatory system,  

which enables our sense of taste and includes  the tongue and gustatory cortex of the brain.

When you take a bite of okonomiyaki, special  cells in your taste buds respond to molecules  

in that warm mouthful of cabbage, sprouts,  noodles and sauce. Those cells will send  

signals to your brain that lead to the taste  of sweet, salty, bitter, sour, or umami.

And of course, you’re holding that warm styrofoam  container in your hand. The feel of that warmth  

of the container is a sensation that you and  I would call touch. But other people refer to  

it as a somatosensory sensation, which is a part  of the somatosensory system, or our fifth sense.

Think of the somatosensory system as  the way our body interprets sensory  

information from the very exterior bits  of us—things like pressure, temperature,  

and pain. It also includes proprioception, or the  physical awareness of where your body is in space.

And when it comes to movement, we have  a specific part of proprioception:  

the vestibular sense. Thanks to the vestibular  sense we can hold our heads up correctly,  

balance when walking, and even  focus our eyes on things in motion.

The vestibular sense is kind of like our sense  

of gravity and is made possible  by structures in the inner ear.

What we feel with our somatosensory system  varies across the body, and part of this is  

because the map of our body that lives in our  cerebral cortex, the somatosensory homunculus,  

is not at all related to Voldemort or what our  body actually looks like! Which is probably a good  

thing, because if that were the case, it would  look something like this. It’s kind of terrifying!

Basically, the more sensitive an  area of your body is to touch,  

the more space your somatosensory cortex devotes  to it. This is why a paper cut hurts more than  

you think – there’s so much more brain  processing power devoted to your hands!

And there are still more senses, like  interoception.That’s the sense we use  

to gather signals from inside the body. There are  lots of body processes that we can pay attention  

to if we focus, like our heartbeats, internal  temperature, or even the stomach rumbling.

Once sensory information reaches the brain, it’s  translated through a process called transduction  

into sensations that we feel. And when the  information is processed, then we have perception.

Perception is biological too since  it involves cells sending signals,  

but we can think of perception as psychological  because it’s shaped by many factors,  

including your background, culture, language, and  worldview. As we saw with the people of Berinmo,  

the names we learn for colors can  affect our perception of colors.

And this biological and psychological combination  completes our perception. Whether it’s colors or  

sounds or some other sensation, the way we process  sensory information can be divided into two types.

The first is called Bottom-up processing,  and it represents how perception is built  

on information from our senses. Like, when  you take the first bite of a new food,  

you’re taking in the way it tastes and  smells to figure out if you like it.

But we also use top-down processing, which  is when prior knowledge influences how we  

perceive something new. Maybe you’ve never  tried vegemite before, but when you eat it,  

it reminds you of eating another type of  salty spread that you really didn’t like.  

So the similarity is affecting  what you think of the vegemite.

So our senses are more complex than  just a raw feed of information about  

the world -- we also have to  organize this information in  

our minds. We need both sensation and  perception to understand the world.

So let’s dig into that gray area  between sensation and perception,  

because one doesn’t always  straightforwardly lead to the other.

Imagine I stimulated your sense of touch by  tickling your arm very gently. So gently that it  

only registers in your brain part of the time. The  sensation is always there -- I’m always tickling  

you and the cells on your arm are taking in that  information -- but it’s not always perceived.

That’s in part because our brains limit  what sensory information we perceive.  

Which is a good thing! If you think the  open-plan office is already a nightmare,  

imagine if we were aware of all  the things our senses picked up  

in that environment – every cough, every  Slack ping – total information overload.

To study the relationship  between sensation and perception,  

researchers use something called absolute  threshold, which is the smallest amount  

of stimulus that we can register 50% of the  time. (For consistency when doing research,  

we use detecting a stimulus 50% of the time  for the definition of absolute threshold.)

Like we said though, the sensation is always  happening. So when a stimulus doesn’t cross  

the absolute threshold, we call it a subliminal  message. And even though we’re not aware of it,  

there’s some evidence that subliminal messages  can affect our thoughts. Researchers are  

investigating just what kind of messages  can affect our thoughts...and for how long.

Then there are times when sensation does  become perception, but we misinterpret the  

sensory stimuli. We call these mismatches  between sensation and perception illusions.

Even though optical illusions – like the vase  with faces or the blue-gold dress of internet  

yore – seem to get all the attention,  illusions can involve different senses…  

or more than one!. For example, look closely at  my mouth and try to guess what sound I’m making.

Did you hear da da da? Most people do!

Ok, now, this time, close your eyes. NO PEEKING!

Did you hear ba ba ba this time?

Now, let’s try one more time  - this time, without sound.

Did you see ga ga ah ah aah…  er, sorry. Did you see ga ga ga?

Here’s the thing: you might have heard – or seen  – the words differently depending on what kind  

of stimulus your senses were getting. But  the actual audio and video never changed!

This is called the McGurk Effect. It’s an illusion  that occurs when the visual component to one sound  

is paired with the auditory sound of another  word, leading you to perceive a third word  

entirely. Basically, your senses are at war with  one another, and your brain has to sort out the  

contradictory information it’s getting from your  eyes and ears to make sense of what’s going on.

The McGurk Effect is an example of how illusions  are more than just interesting tricks. By studying  

them, researchers can learn more about how  our senses work. That’s important because  

as we’ve discussed, the senses don’t  work the way we might assume they do.

It also shows us that our senses don’t  exist in isolation from one another,  

and that while our brain is always  receiving sensory information,  

we can't always trust if or how  we’re perceiving that information.

Sometimes our senses seem completely infallible,  like they’re bringing us the true reality of  

the physical world. But our senses are  nothing without our prior experiences,  

culture, language, and identity. And our  senses of course have their limitations.

The way you sense the world may seem incredibly  natural and intuitive, but it’s the result of  

extraordinarily complex processes, processes that  might play out differently for other people. The  

reason you think green is green and vegemite  tastes terrible is because of your senses  

and the way perceptions are organized in your  brain. Different people’s brains create different  

sensory experiences, and the way we experience  sensory information can change over time too.

So the next time you wonder why a friend chose to  wear a fuchsia turtleneck with violet corduroys,  

keep this in mind! Maybe those  colors don’t clash for everyone.

If you’re enjoying Study Hall Intro  to Psychology and are interested in  

taking an online course and earning  college credit, go to gostudyhall.com  

or click on this button to learn more.  Thanks for watching, see you next time!