Psychology of the Senses : Documentary on Sensation and Perception (Full Documentary)

Summary

This program delves into the fascinating world of perception, exploring how our brains are tricked by visual illusions and the complexities of sensory processing. From the remarkable abilities of different species to the intricate workings of the human brain, the script uncovers the mechanisms behind our perceptual experiences, highlighting the role of bottom-up and top-down processing in creating a stable and meaningful interpretation of the world around us.

Takeaways

• 🎨 Visual illusions can trick the brain due to the way our perception system processes and interprets visual information.
• 🧠 Perception is a critical survival tool that allows us to make contact with our environment and gather essential information.
• 👀 Our sensory abilities are measured by the absolute threshold, which is the weakest level of a stimulus that can be detected half the time.
• 🌆 Perception involves both bottom-up processing, where raw data from sensory receptors is sent to the brain, and top-down processing, which adds our prior knowledge and context to the interpretation.
• 🔍 The brain performs complex transformations to interpret sensory information, such as eliminating confusing signals and giving objects three dimensions.
• 🏥 The occipital lobe in the brain is primarily responsible for processing visual information, while other lobes handle different types of sensory input.
• 🐦 Different species have developed specialized sensory apparatuses for survival, such as the keen vision of eagles or the sonar of bats.
• 🤔 Perceptual constancy allows us to perceive objects as relatively stable despite changes in the sensory input, such as size or brightness.
• 👁️ The visual system breaks down visual stimulation into millions of bits of information and recombines them into a coherent image that we recognize.
• 🤹‍♂️ Our brain can sometimes create phantom patterns or subjective contours, where we perceive a boundary or edge that doesn't physically exist.
• 🏈 Adaptation to altered perception, such as wearing glasses that displace visual feel, requires the brain to learn new arm-eye coordination, demonstrating the brain's plasticity.

Q & A

How does the brain get tricked by visual illusions?

The brain gets tricked by visual illusions because it performs an instantaneous analysis of visual information, making assumptions based on past experiences and the context of the situation. These assumptions can lead to misinterpretations, such as perceiving size or shape incorrectly.

What is the role of perception in our interaction with the environment?

Perception is our way of making contact with our environment, discovering what's happening outside our body. It is crucial for survival as it allows us to gather essential information through our senses and respond appropriately to our surroundings.

How do different species develop sensory apparatus for survival?

Different species develop special sensory apparatus to gather information essential for their survival. For example, eagles have extremely accurate vision, dogs can smell in much lower concentrations, and bats use sonar to track and catch insects.

What is the absolute threshold in sensory perception?

The absolute threshold is the weakest level of a stimulus that can be accurately detected at least half the time. It varies for different senses and is a measure of our sensory abilities.

How is visual information processed in the brain?

Visual information is processed in several stages. It starts in the retina, then moves through the optic nerve to the brain, where it is further processed in the occipital lobe and other cortical areas. The visual cortex is responsible for interpreting the information and forming a coherent image.

What are the roles of the rods and cones in the retina?

Rods and cones are photoreceptor cells in the retina that detect light and color. Rods are sensitive to low light conditions, while cones are responsible for color vision and function best in bright light.

How do the brain's transformations of visual information help in perceiving the real object?

The brain transforms the visual information by eliminating confusing signals, filling in gaps, and giving the image three dimensions. It corrects the upside-down image and puts everything in perspective to determine the true nature of the actual object, known as the distal stimulus.

What is the significance of perceptual constancy in visual perception?

Perceptual constancy allows us to perceive the actual size, shape, orientation, and brightness of an object as relatively constant, even when there are variations in the retinal image. This helps us maintain a stable perception of our environment despite changes in viewing conditions.

How does the brain use context to influence perception?

The brain uses context to interpret sensory information by comparing it with what we already know and expect. This top-down processing adds meaning to our perceptions, allowing us to see things in a way that makes sense given the situation.

What is the concept of subjective contours in visual perception?

Subjective contours are phantom patterns that the brain perceives even when they are not physically present. They occur when the brain detects a boundary or edge and extends that difference across a surface, creating the illusion of a complete shape or pattern.

How can our expectations and biases affect our perception?

Our expectations, interests, and biases can influence our perception by predisposing us to see what we expect to see or not see what we do not expect. This can lead to misinterpretations or overlooking certain details in our environment.

Outlines

00:00

🎨 Visual Perception and Illusions

This paragraph delves into the fascinating world of visual perception, exploring how our brains can be deceived by visual illusions. It starts with an introduction to the program's funding and purpose, then transitions into an interactive demonstration at the Exploratorium in San Francisco, where the presenter manipulates perception to appear larger or smaller. The discussion explains how our brains use visual information and past experiences to make instantaneous judgments about size and shape, often leading to misperceptions. The paragraph also touches on the importance of perception in survival, the absolute threshold of sensory detection, and the various sensory apparatuses developed by different species.

05:03

👀 Understanding Sensory Perception

The second paragraph provides an in-depth look at how sensory information is processed by the human brain. It explains the role of specialized receptors in detecting physical energy, such as light and sound waves, and converting these into neural impulses. The journey of these impulses from the sensory organs to the brain's cortex is detailed, highlighting the分工 of different cortical regions in processing various senses. The paragraph further discusses the primary sensory centers, the thalamus as a relay station, and the abstract information processing that occurs in the cortex. It also touches on the Nobel Prize-winning work of David Hubel and Torsten Wiesel on receptor cells in the visual pathway and the complexity of early vision processes.

10:04

🤖 The Complexity of Visual Processing

This paragraph examines the intricate process of visual information processing, from the initial reception of light by the retina to the recognition of objects. It describes how the visual system breaks down an image into millions of bits of information, using computer graphics to illustrate the point. The discussion includes the role of edge and line-detecting neurons in identifying object boundaries and the concept of constancies and simplicity in object recognition. The paragraph also explores the idea of motion perception and rigidity, using examples of rotating squares and crosses to demonstrate how the brain interprets motion. The importance of perceiving motion and the challenges of creating a seeing robot are emphasized, highlighting the complexity of visual perception.

15:06

🏈 Perception in Action and Adaptation

The fourth paragraph discusses the practical applications of perception, particularly in the context of sports, such as American football. It describes how a quarterback uses perception to calculate distance, angle, and velocity for passing the ball. The paragraph also introduces an experiment with glasses that distort visual perception, demonstrating how the brain adapts to new visual information and the consequences when perception returns to normal. The discussion extends to the concepts of bottom-up and top-down processing, explaining how our prior knowledge and context influence our perceptions. The paragraph concludes with examples of perceptual constancy and the active role our minds play in shaping our perceptions of reality.

20:08

🔍 The Active Nature of Perception

This paragraph explores the active nature of perception, emphasizing that our brains constantly select and process only a small part of the available sensory information. It discusses how context can significantly influence perception, using examples of a square appearing darker against a lighter background and the size comparison of three men. The paragraph also touches on the speed and efficiency of perception, highlighting the importance of edges and boundaries in conveying information about an object. The discussion includes the concept of subjective contours, where the brain registers patterns that do not exist, and the influence of our expectations, interests, and biases on perception.

25:09

🕵️‍♂️ Perception and the Limits of Understanding

The final paragraph addresses the limitations of perception and the role of our brain in organizing and interpreting sensory information. It discusses how our expectations and experiences can sometimes lead us astray, causing us to see things that aren't there or fail to see things we don't expect. The paragraph presents various visual paradoxes and illusions, such as the impossible triangle and the bouncing ball animation, to illustrate the conflict between analytic and holistic ways of seeing. It concludes with a reminder of the sophistication of our sensory apparatus and the software of our brain, which, despite occasional discrepancies, usually work together effectively to make sense of the world around us.

Keywords

💡Perception

Perception is the process by which the brain organizes and interprets sensory information to understand our environment. In the video, perception is central to the theme as it explores how our brain can be tricked by visual illusions and how we misjudge objects or events. For example, the script discusses how our brain performs an 'instantaneous analysis' when the room's lights change, leading to a misperception of size.

💡Visual Illusions

Visual illusions are phenomena where our visual system interprets images differently from reality, often due to the brain's inherent assumptions about the world. The video uses visual illusions to illustrate how our perception can be deceived, such as the rotating square that appears to expand and contract, demonstrating the brain's struggle to reconcile sensory input with prior knowledge.

💡Sensory Apparatus

Sensory apparatus refers to the body's specialized organs and structures that detect and respond to different types of physical energy, such as light, sound, and pressure. The script mentions that all species have developed sensory apparatuses like the acute vision of eagles or the sonar of bats, which are crucial for survival and gathering essential information from the environment.

💡Absolute Threshold

The absolute threshold is the minimum level of a stimulus that can be detected half of the time. It is a measure of our sensory abilities, as explained in the script with examples like seeing a candle flame at 30 meters or detecting a single drop of perfume in a three-room apartment. This concept is key to understanding the sensitivity of our perceptual systems.

💡Neural Impulses

Neural impulses, or action potentials, are electrochemical signals that convey information throughout the nervous system. The script explains that sensory receptors convert physical energy into neural impulses, which are then transmitted to the brain for processing, highlighting the critical role of these impulses in the perception process.

💡Cortex

The cortex, specifically the cerebral cortex, is the outer layer of the brain involved in higher cognitive functions, including sensory perception. The script describes how different regions of the cortex process various types of sensory information, emphasizing its importance in integrating and interpreting sensory data.

💡Distal Stimulus

The distal stimulus refers to the actual object or event in the environment that is perceived. The video script uses this term to discuss how the brain uses sensory information to determine the true nature of the object, despite the limitations and distortions present in the proximal stimulus, or the image formed on the retina.

💡Perceptual Constancy

Perceptual constancy is the ability of our visual system to perceive objects as unchanged in size, shape, and color despite variations in the sensory input. The script mentions this concept when it talks about how we perceive the size of people as constant even though the retinal image changes with distance, illustrating the brain's ability to impose stability on our perceptions.

💡Bottom-Up Processing

Bottom-up processing is a perceptual mechanism where sensory receptors detect external stimuli and send raw data to the brain for analysis. The script contrasts this with top-down processing, explaining that bottom-up processing is the initial step in perception where the sensory input is collected before being interpreted in the context of our existing knowledge.

💡Subjective Contours

Subjective contours refer to the phenomenon where our brain perceives a boundary or edge even when there is no physical stimulus present. The script provides an example where the brain extends a slight difference in brightness across a surface, creating the illusion of a contour where none exists, demonstrating the brain's tendency to impose order on visual information.

💡Eyewitness Testimony

Eyewitness testimony involves a person's recollection of an event they have witnessed. The video script discusses the unreliability of such testimony, suggesting that the perceptual processes can be flawed, especially under stress or when the brain is unprepared to process rapid sequences of events, as illustrated in the simulated bank robbery scenario.

Highlights

The brain is tricked by visual illusions due to its reliance on past experiences and expectations to interpret sensory information.

Perception is a crucial survival tool that allows us to make contact with our environment and understand what's happening around us.

Different species have developed unique sensory apparatuses, such as eagles' sharp vision and dogs' heightened sense of smell.

Psychologists focus on visual perception, which is processed in the occipital lobe and involves multiple stages of neural activity.

The absolute threshold measures the weakest level of a stimulus that can be detected half the time, highlighting the sensitivity of human senses.

Sensory receptors convert physical energy into neural impulses, which the brain's cortex interprets into various psychological experiences.

The primary visual cortex processes visual information, which is initially an upside-down, distorted image on the retina.

The brain performs transformations to eliminate confusing signals and give depth and perspective to the visual information received.

David Hubel and Torsten Wiesel's research on receptor cells in the visual pathway won them a Nobel Prize, shedding light on how we see.

The visual system breaks down visual stimulation into millions of bits of information, reassembling them into a coherent image.

Perception involves both bottom-up processing, which detects external stimulation, and top-down processing, which adds context and meaning.

Perceptual constancy allows us to perceive objects as relatively constant despite changes in the sensory input they project.

Our expectations and biases can lead to different perceptions, as seen in the varying interpretations of ambiguous figures.

Subjective contours demonstrate how the brain can create perceived edges even where there are none, influenced by surrounding context.

Eyewitness testimonies can be unreliable due to the brain's quick reactions that may outpace its ability to accurately process visual information.

Visual paradoxes challenge our understanding of what is possible, as our brain uses both analytic and holistic ways of seeing to make sense of objects.

The program explores the sophisticated interplay between our sensory apparatus and the brain's software for processing information and making sense of the world.

Transcripts

funding for this program is provided by

anenberg cpb to advance excellent

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teaching how is our brain tricked by

visual

Illusions what makes a Star Quarterback

misjudge an Easy Pass

why does this rotating Square appear to

expand and

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contract sensation and perception this

time on discovering

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[Applause]

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psychology

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lights camera

perception when you were little and some

big kids pushed you around did you ever

fantasize about becoming bigger all of a

sudden

well I did and now I can at the

Exploratorium San Francisco's Science

Museum how did I do it the easy way by

manipulating your perception when you

first saw me I appeared to be normal

size because you couldn't see the rest

of the room but as the lights came up

and the camera pulled back your brain

performed a new instantaneous analysis

it now saw me as small it added up all

all the visual information it had about

my size and the size and shape of the

room and then it added in everything it

knew from experience about the usual

shape of rooms that they're rectangular

and have right

angles so when I walked over here your

brain was convinced I was growing

incredibly large because there was no

other perceptual explanation even though

it wasn't

logical let's look at it again only this

time from a different perspective the

room is not rectangular at all it's

totally distorted there are no right

angles anywhere so that makes this clock

which is large and oval look the same as

that clock which is small and circular

from your other perspective the floor

slopes upward as you can see the ceiling

slopes

downward so I'm not getting larger at

all you're just miss perceiving my size

because you think that you're the same

distance from me when I'm over here as

you are from me me when I'm over

there but in fact I'm twice as far

away it's always more fun to have a

vivid example of

misperception but the truth is our

perception is usually very accurate it

has to be we couldn't survive if it

weren't perception is our way of making

contact with our environment of

discovering what's happening outside our

body and our

brain all species have developed special

sensory apparatus to gather information

essential for

survival Eagles and other birds of prey

have astonishingly accurate

Vision dogs can smell things in

concentrations a 100 times lower than we

can and bats can use sonar to track and

Capt tiny fast moving

insects psychologists study all sensory

processes hearing smell taste and so on

but their major focus and ours is on

visual perception our sensory abilities

are usually measured by the absolute

threshold the weakest level of a

stimulus that can be accurately detected

at least half the

time for you humans that includes a

candle flame seen at 30 m on a dark

clear

night the tick of a watch under quiet

conditions at 20

ft one teaspoon of sugar in 2 gallons of

water one drop of perfume diffused in

the space of a three room

apartment the wing of a bee for rolling

on your cheek from a distance of 1

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cm our sensory knowledge of these

stimuli comes from the many millions of

specialized receptors spread throughout

our

bodies in Our Eyes Ears Nose tongue skin

muscles our joints and tendons our inner

ear and even certain parts of our

digestive

tract each receptor is designed to

detect certain types of physical energy

such as light waves or sound waves this

stimulation is then converted into a

special code electrochemical signals

called neural impulses which the nervous

system transmits to the brain's

cortex the cortex has the job of putting

all the sensory information together and

acting upon it different regions of the

cortex translate different neural

impulses into different psychological

experiences such as melody or

touch visual information is first

processed in the occipital lobe area in

the rear of the brain hearing and smell

in the temporal lobe speech perception

in the frontal lobe and body senses in

the parietal lobe these primary sensory

centers then project the results of

their activity to a relay station the

thalamus which in turn sends the

information to a succession of areas in

the

cortex it's believed that this is where

more abstract information processing

takes place and where we connect new

information with old information stored

in our

memory visual perception for instance

takes place in three areas in the retina

or the back surface of the eye in the

pathways through the brain and in the

part of the cortex at the back of the

brain resp responsible for visual

processing the visual

cortex this is the way an image or

rather a pattern of stimulation is

formed on the retina it's upside down

flat distorted full of holes out of

focus and obscured by blood vessels in

fact it's amazing that we see as well as

we

do now remember that the task of all

perception is to determine what the real

object in the environment is another

term for this object is the distal

stimulus the thing out there but the

only way to find out what that is is by

using information derived from the

object stimulation of a sensory receptor

in the body this stimulation is called

the proximal stimulus in this case an

image formed on the retina the brain

knows only the image but what it must

discover is the true nature of the

actual object the distal stimulus

so here's where the brain earns its keep

it must eliminate confusing

signals fill in the

blanks give it three

dimensions and straighten out the upside

down image to put it all in

perspective these Transformations occur

instantly and

continually David Yubel of Harvard won a

Nobel Prize with his colleague Toren

visel for mapping the action of receptor

cells along the visual path of a primate

from the retina to the cortex receptor

cells usually in a v in the visual

pathway mean the cells that take in the

energy and turn them it into electrical

signals and in the retina those are the

rods and cones there are 125 million

rods and cones in each retina so in the

case of the visual pathway you start

with the retina the output put is the

optic nerve which contains a million

fibers they end up in a certain region

in the

brain that region or there really two or

three regions that they end up in uh

each of those sends a cable of fibers of

the order of maybe a million to other

regions and they connect to other

regions and in the case of the cortex

you have separate areas of Cortex each

one connected to one or more other areas

and this whole thing is a pathway in the

cortex for example the primary visual

cortex which is about seven stages

Beyond The receptors in the retina those

cells uh react to visual stimula only if

the if a line falls on the retina and

the line has to be a particular

orientation can be a bright line or a

dark line or an edge between bright and

light any kind of line really generally

works but the position of the line and

the orientation are terribly important

and if they're not just right any

individual cell doesn't doesn't

respond in this experimental footage a

bright vertical line stimulates a small

number of neurons in the visual cortex

of a cat the crackling sound is the

electrical activity of these neurons as

they respond to this retinal image by

listening to the intensity of this

electrical activity the researchers can

determine the correct orientation of the

line

but when the line is moved to a diagonal

or horizontal position the amount of

stimulation decreases

dramatically we're only at a very

Elementary stage when it comes to

understanding something like how you

recognize a face or something like that

the the general region of the brain is

known where where things like that go on

but we don't have the slightest idea of

what's happening at the level of single

cells for that particular problem but

for more Elementary problems for the the

very first uh processes of vision we do

have a very good understanding what

happens at the very beginning so it's

just a

start Misha Pavel of Stanford University

is studying the successive stages of

information processing that take place

continually as we perceive the world

using computer Graphics he has

demonstrated how the visual system

breaks down VIs ual stimulation into

millions of bits of information and

recombines them into a coherent image

that we recognize seeing something is

seems such an effortless activity that

it's hard to imagine for us the

complexities and difficulties that are

involved only when you try to build a

robot that can actually see and

recognize objects do you realize how

complicated task this is people can must

do awful lot of processing in order to

see images and interpret them here is an

image of a cat as our eye and brain sees

it now let's look at what the visual

system goes through to enable us to see

this image when the light first reaches

the retina the image is slightly

defocused by the Optics of the eye then

it is broken up into millions of little

pieces each receptor sees just a

minuscule portion of the original image

and measures its brightness different

receptors in the retina are sensitive to

different colors of light and respond to

the amount of that color that they

see to discover objects the visual

system tries to find important

boundaries it uses Edge and line

detecting neurons whose characteristics

have been investigated by hubel and

visel here you can see the results of

the

red

green and blue edge detectors look at

the blue edges it is hard to believe

that there is a cat in

there what I like to show you now is the

kind of information that the brain uses

in order to make sense out of these

messy

images the things that the brain seems

to look for are constancies and

simplicity imagine that you are in your

visual system looking at this pattern of

active neurons but you can't recognize

the

pattern we can see it now because all

the points in the cat picture move

together this is an example of the brain

using rigidity to recognize moving

objects ambiguous perception of motion

can actually destroy the rigidity

percept in this case we have a rotating

rigid object a square but when its

Corners

disappear appear appear from view the

square appears to get

smaller when the cers reappear it gets

larger another example we thought that

the square loses its rigidity because

the visual neurons at each location can

see only a small proportion of the

entire picture and therefore can't

accurately perceive the direction of the

moving parts of the object if we rotate

the cross then the stationary Square

appears to be

rigid we can simultaneously compare

these two

situations the conclusion is that the

motion of the square is necessary to

lose rigidity the failure of rigidity in

this case helps scientists to study how

information from different retinal

locations is combined to form a single

percept this is one of many examples

where percep show phenomena can reveal

how our brain

works

every moment the brain must make an

endless number of perceptual decisions

it has to compute size and distance

relationships determine where boundaries

and edges exist identify figures within

backgrounds move us toward objects we

want and away from objects we need to

avoid many of these perceptual decisions

are made without any conscious awareness

of the processes involved

the brain is automatically Computing the

sensory feedback and guiding the body to

perform the necessary

tasks when a quarterback sees a receiver

for instance he automatically

unconsciously calculates distance angle

and velocity and the muscles in his hand

arm and shoulder adjust

accordingly but what if we distort his

perception of the receiver these glasses

will displace his visual feel by 20° in

other words the distal stimulus the real

object will be 20° off from where he

perceives it to

be if he continues to pass with the

glasses on he'll begin to adapt to the

new signals by compensating for the

misinformation his retina is sending to

his

brain he'll start throwing what seems to

him to be 20° off in order to hit the

receiver he has quickly learned a new

arm eye

coordination but return his vision to

normal and he'll start missing again in

the opposite

direction even though his retina is now

passing on accurate information about

the true location of the target his

brain hasn't caught up with the new

input his brain is still compensating

for the previous feedback from the

movements in his hand and arm

getting accurate information about the

world around us and not just the images

on a retina is the major task of our

visual system but to sense perceive and

understand our world we utilize two very

different processes first our sensory

receptors detect external stimulation

and send this raw data to the brain for

analysis we call this bottom up

processing then top down processing

enters the scene it adds what we already

know about such stimulation what we

remember about the context in which it

usually appears and how we label and

classify it in this way we give meaning

to our

perceptions when people walk towards us

we know that they're not getting larger

even though the image they cast on the

retina does get

larger and if a shadow falls on our

newspaper we know the paper isn't

turning darker

that's because the hallm mark of

perception is our ability to impose

stability on the constantly changing

flow of Sensations we

experience psychologists refer to this

phenomenon as perceptual constancy the

actual size shape orientation and

brightness of an object are perceived as

remaining relatively constant even when

there are extreme variations in the

image IT

projects

what we perceive is not just a passive

photograph of reality but an active

construction of reality we tend to see

what we expect to see we see things with

our minds as well as our

eyes we are constantly selecting only a

small part of the available sensory

information to attend to and

process one of the ways we perceive

something actively is by taking into

account its context this context can

even determine the nature of the

perception itself with the same object

looking very different in different

contexts take a look at this

Square notice how the square appears to

get darker as the background becomes

lighter or in other words as the context

changes now take a look at these three

men we see the figure on the right as

smaller than the one on the left in back

because we unconscious iously compare

him with the large figure but in fact

the two small figures are exactly the

same

size to be effective perception also has

to work fast and extract the minimal

amount of information necessary to form

an impression of the entire pattern

visual perception would be far too slow

we had to wait to experience every last

piece of

something edges and boundaries in

particular convey lots of information

about an object they provide a visual

shortcut which can help the brain fill

in the whole pattern from the fewest

identifying

Parts sometimes the brain will even

register a pattern that doesn't exist

these Phantom patterns are called

subjective

Contours a boundary or an edge can

powerfully influence the way we see

things in this example Le the left half

of the screen appears darker than the

right half but watch what happens when

we cover up the

boundary what happened is this your

brain detected a slight difference in

brightness in the center and then went

overboard and extending that difference

to the rest of the

surface given the complexity of the

world we try to understand and the

complexity of our minds it's small

wonder that what we perceive as out

there is subject to a great number of

influences some of which will lead us

astray we may see something that isn't

there because it's what we expect to see

or conversely we may not see something

because we don't expect to see it our

previous experience our

expectations interests and biases are

constantly giving rise to different

perceptions let's take a look at this

illustration

some of you will see a young woman and

some of you will see an old woman in

various studies it was found that

younger people tended to see the younger

face while older people tended to see

the older face without any hints about

what to look

for and then there's the ratman illusion

try to identify each drawing as soon as

you see

it now identify this

one let's try another

sequence again identify each drawing as

soon as you see

it now how about this

one in a number of studies it was found

that the first series of drawings of

animals LED most subjects to identify

this image as a

rat but when other subjects saw the

drawings of people they tended to

identify this drawing as an old man with

glasses their prior experiences created

very different ways of looking at the

same distal

stimulus sometimes however we have

trouble perceiving things not because of

our experiences or our expectations but

just the opposite there's just too much

unfamiliar information to absorb we're

taken by

surprise but surprise is what often

happens to

eyewitnesses watch the simulated bank

robbery again and try to tell who did

what

who shot

whom would you swear to it in

court let's show the film this time in

slow motion to see if you were

right the hand the arm even the whole

body can be quicker than the eye when

the brain isn't ready to do its

detective

work what happens when we have no

trouble seeing something but what we see

just doesn't Mak sense when we encounter

a visual

Paradox at first glance this is a solid

wooden

triangle but it can't be a triangle

because from my perspective it has two

right angles and that's impossible so

impossible I want you to watch this as I

slice my arm right through without

breaking it so now you know that it

can't be solid either changing the

perspective enables you to see it as it

really is we call this way of seeing an

object in terms of its parts the

analytic way of seeing which conflicts

with the holistic way of seeing the big

picture either of you Mak sense alone

but

together they create a

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paradox in this animation of a bouncing

ball the staircase appears to go up

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forever this Paradox all also works in

Reverse Although our senses put us in

touch with the world around us it's our

brain working from prior experiences

that tells us whether something is

impossible or possible organizing our

perceptions and telling us what's out

there and what we should think about

it and so each of us has incredibly

sophisticated Hardware in the form of

sensory

apparatus and software to process the

information and make sense of it both

perfected over millions of

years usually the two work together

extremely

well but sometimes they don't and so we

can never take perception for granted no

matter how well we do it in the normal

course of our

lives in our next program we're going to

look at another ability of ours that

shapes the way we look at the world and

that's our ability to learn to profit

from experience a tale of mice and men

and women next time I'm Philip

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zimbardo

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funding for this program is provided by

anenberg cpb to advance excellent

teaching

for information about this and other

anenberg cpb programs call one800

learner and visit us at

www.learner.org