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Our world is three-dimensional, so it makes sense that our mental representation of the world has three-dimensional properties. We use a variety of cues in a visual scene to establish our sense of depth. Some of these are binocular cues , which means that they rely on the use of both eyes. One example of a binocular depth cue is binocular disparity    , the slightly different view of the world that each of our eyes receives. To experience this slightly different view, do this simple exercise: extend your arm fully and extend one of your fingers and focus on that finger. Now, close your left eye without moving your head, then open your left eye and close your right eye without moving your head. You will notice that your finger seems to shift as you alternate between the two eyes because of the slightly different view each eye has of your finger.

A 3-D movie works on the same principle: the special glasses you wear allow the two slightly different images projected onto the screen to be seen separately by your left and your right eye. As your brain processes these images, you have the illusion that the leaping animal or running person is coming right toward you.

Although we rely on binocular cues to experience depth in our 3-D world, we can also perceive depth in 2-D arrays. Think about all the paintings and photographs you have seen. Generally, you pick up on depth in these images even though the visual stimulus is 2-D. When we do this, we are relying on a number of monocular cues , or cues that require only one eye. If you think you can’t see depth with one eye, note that you don’t bump into things when using only one eye while walking—and, in fact, we have more monocular cues than binocular cues.

An example of a monocular cue would be what is known as linear perspective. Linear perspective refers to the fact that we perceive depth when we see two parallel lines that seem to converge in an image ( [link] ). Some other monocular depth cues are interposition, the partial overlap of objects, and the relative size and closeness of images to the horizon.

A photograph shows an empty road that continues toward the horizon.
We perceive depth in a two-dimensional figure like this one through the use of monocular cues like linear perspective, like the parallel lines converging as the road narrows in the distance. (credit: Marc Dalmulder)

Stereoblindness

Bruce Bridgeman was born with an extreme case of lazy eye that resulted in him being stereoblind, or unable to respond to binocular cues of depth. He relied heavily on monocular depth cues, but he never had a true appreciation of the 3-D nature of the world around him. This all changed one night in 2012 while Bruce was seeing a movie with his wife.

The movie the couple was going to see was shot in 3-D, and even though he thought it was a waste of money, Bruce paid for the 3-D glasses when he purchased his ticket. As soon as the film began, Bruce put on the glasses and experienced something completely new. For the first time in his life he appreciated the true depth of the world around him. Remarkably, his ability to perceive depth persisted outside of the movie theater.

There are cells in the nervous system that respond to binocular depth cues. Normally, these cells require activation during early development in order to persist, so experts familiar with Bruce’s case (and others like his) assume that at some point in his development, Bruce must have experienced at least a fleeting moment of binocular vision. It was enough to ensure the survival of the cells in the visual system tuned to binocular cues. The mystery now is why it took Bruce nearly 70 years to have these cells activated (Peck, 2012).

Summary

Light waves cross the cornea and enter the eye at the pupil. The eye’s lens focuses this light so that the image is focused on a region of the retina known as the fovea. The fovea contains cones that possess high levels of visual acuity and operate best in bright light conditions. Rods are located throughout the retina and operate best under dim light conditions. Visual information leaves the eye via the optic nerve. Information from each visual field is sent to the opposite side of the brain at the optic chiasm. Visual information then moves through a number of brain sites before reaching the occipital lobe, where it is processed.

Two theories explain color perception. The trichromatic theory asserts that three distinct cone groups are tuned to slightly different wavelengths of light, and it is the combination of activity across these cone types that results in our perception of all the colors we see. The opponent-process theory of color vision asserts that color is processed in opponent pairs and accounts for the interesting phenomenon of a negative afterimage. We perceive depth through a combination of monocular and binocular depth cues.

Personal application question

Take a look at a few of your photos or personal works of art. Can you find examples of linear perspective as a potential depth cue?

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Questions & Answers

is there any scale for measuring post COVID Anxiety?
Richard Reply
I'd like to know if there's any?
Zino
I've heard about Coronavirus Anxiety Scale (CAS). It works as a mental health screener but I'm not sure anyone can do the test except psychologist
divani
Thanks !
Zino
explain the function how intelligence and learning function together
Truvanie Reply
Learning comes before intelligence Learning could be the process of acquiring knowledge. Or the ability to gain knowledge Whereas intelligence is the display of acquired knowledge.
Felix
schools of psychology
Onogwu Reply
hi
giri
hi
Swapnil
hi
Munir
hello
Imsekar
hai
Tu
Hi
piya
hello
kajal
Hello
Mohamed
hii
grace
hi
george
hi
Anuja
hi
kajal
gud night
grace
Good night everyone
Anuja
good night 😴🌃
Swapnil
hello
Ananya
What's the point of this chat section?
Mohamed
to say hello and to feel solidarity.
Tu
the early childhood can reference the emotions?
Sammi Reply
Our early childhood experiences are important in the development of our personalities. It kind of shapes our behaviour and mannerism.
Debarpita
Especially in choosing career
Felix
😅Well that's complicated. It differs from person to person.
Debarpita
The early childhood or let's say your upbringing plays a vital role in driving your emotions. If one did not have a pleasant childhood it's highly likely they are more vulnerable to depression or some other psychological condition.
Indefatigable
how to change the emotion?
Sammi Reply
change the thought at hand .
Shawnte
Then I'm assuming the mind will begin to let go of the prior emotion.
Shawnte
Yes right. Think about something else, then emotion will follow.
Annie
then join life
Munir
I don't understand about this
Munir
how has the new legalization of marijuana effected the anti drug programs
Summer Reply
how to change the emotional ?
Sammi
I am wrilly interisting about big problems psihycil nature between famillys/like parents bully some childe physically , even hall life and show some kinde of heath and $inaid
Zorica Reply
same
Gaea
Never give minor issues space. Time creates space, more time more space therefore if u give a small issue more time it gets more space in your mind hence breeding stress
Andrew Reply
yes yes yes so true
Gaea
hi..my brother gets angry Everytime I say no to him for anything he ask for he don't talk to me after that.. Everytime I only have to say sorry so this time I decided not to say sorry he haven't talked to me for two weeks I am so stressed what should I do
Nush
give him so time. I think you should let him figure out his own feelings. plus, you did the right thing. he needs to know that not everyone will give him what he wants.
Gaea
Don't be stressed out . You did right thing. but remember one thing don't show angry gestures to him or don't try to make him realize by teasing or scolding. If you try to be humble and patient, he may understand his mistake on his own.
PARUL
yeah
Gaea
Hi everyone! So i'm gonna be a college freshman soon and i'm gonna major in Psychology😬 but lately i've been worrying about what job i'm gonna have after getting my Bachelor's degree. Any tips or advice?
Angelique Reply
I think minimum of a masters degree is needed in order to get a job once you do mphil and phd u gonna get licence to work as a clinical psychologist and a lot more options 😊best wishes
kitty
hi...my brother gets angry with me anytime I say no to him for anything he ask for and stop talking to me every time I only have to say sorry..so I decided this time not to say sorry he haven't talked to me at all what should I do please help me
Nush
I think it's just a matter of ego and pride.they may have a kind of feeling like if they apologize it hurts their integrity and pride. Some people never admit they are wrong and it creates stress in the other person. .some people are not empathetic and they always want to feel cared n lovedbyother
kitty
so what can we do..if you are a person who always says sorry it's a good indicator that you have such a broad mind where you are ready to solve problems n you love them even though they are bad at you..basically everyone in this whole world is selfish..humans are selfish but there are some people
kitty
like you whom God created just to solve problems and lead other people in a better way..what you should do is create a beautiful bonding bw your bro ask him softly about his problems..love him more..and eventually he may become softer and lovable
kitty
if your bro is an introvert there could be chances where he has got several problems he haven't discussed with anybody which brings out their egoistic behr and blunt nature...ask him to say about his problems..make him understand the importance of apologies and empathetic behr..and try not to end up
kitty
in a fight discussing these things...u should softly deal with it..even if other people let you down or didn't say sorry to you doesn't mean that you r wrong..u are saying sorry everytime because u have a good heart..
kitty
hope this helps🐒have a good day..good life!!😊
kitty
hi..I have a problem.i will emotional fast, every time when I will give any seminar or etc I will get so emotional and I will cry on the stage....what can I do? give me a solution please
Secular Reply
try to think why your on stage and the audience arnt, try to stay positive and maybe meditate before your performance
Raneem
well i personally suggest trying to practice a lot to other people or to yourself be4 stuff like seminars (like rehearsing), but i think you should ask other people too. also like quora is a good place to ask questions and u might get more/better feedback
Aon
i know this is a psychology app, but quora is specifically designed for asking and answering questions (also ask friends/family/etc)
Aon
Coz u scared of society so that ur confidence is very low ...
Arishfa
Take deep breaths it might sound silly but it actually works.. calms your body and mind.don not focus on things like it may go wrong...or what people will think...just prepare and present..💖
kitty
Being emotionl is nt a fault,its gud dat u atleast knw abt it.Accept ur feelings/emotions.Dis time know wht's mking u cry.Is it d topic or ur intrnl feeling abt ur performance?if it's abt prfrmnce jus know dat none s perfect & b confident in ur subjct by practicing it.Remember None can play ur role.
sailaja
i had a problem that;even though i have people around me, I'm feeling lonely
sharath
is there any online facilities to acquire Internship?
Tanvi Reply
psychology is the study of human behaviour,mental processes and experiences.It id because behaviour cant be stable over a period of time hence,it considered subjective.morover, human experiences cant be objective
Rija Reply
Is this a Statement OR a Question ? all things considered, psch has come a long way in its relatively short life. i was getting an "art" degree, when I enrolled, the Pseudo science changed and I landed a science degree instead (worth more when employers look at it)
Lyric
human behavior is fascinating if you ask me, my 1st degree was criminology/investigations, the ultimate goal of the field is control <~~ sounds terrible but in reality it's more about learning to predict the behaviors we need prevented & find a way to stop them before the next school shooting or btk
Lyric
It's needs to be tackle at young age before it heads to the teens stage then sometimes they don't wanna hear it or un cool
Derek
the suffix ology is study of
Mouze Reply
the prefix psyche is the soul
Mouze
iwillbecomeasuideideaseveryday whatareiwilldo
Vijaya Reply
?
BLYTHE
@Vjaya are you OK?
Ashantelle
u should have hope in life...its not that hard as you think...dont give up even though I don't know what you are talking about just pray..breathe...relax..eveything will be fine 💖
kitty
would you like to talk? I'm an advocate for suicide prevention .
Sonya
that's quite gud
sharath
listen buddy if you keep having those thoughts you will manifest bad energy, i recommend listening to positive subliminals for your subconscious mind, and try being positive, it doesn't have to be real just fake it until you make it
stan
ohhh a Loona here?
here a Orbit too
Vijaya I wish I could Help you-
if you're having suicidal thoughts or anything like that, please contact a suicide hotline b/c i think they could help u more more than we could 1-800-273-8255 there are probs other ones just search it
Aon
how are you feeling tho? im kinda confused by the question and i didnt even know this app had a discussion thing
Aon
please call suicide hotline though if you are having suucidal thoughts because they can really help you (definitely more than some of us could) 1-800-273-8255
Aon
please call suicide hotline though if you are having suucidal thoughts because they can really help you (definitely more than some of us could)
Aon
is anyone there
Robin
@vijaya if ur still reading comments, idrk what u meant but please do stay safe and get help if you're feeling badly
Aon
Hii🙋🏽‍♀️
Angelique
please what is the difference between illusion and hallucination
Okugo Reply
d
April
a Hallucination is not real it is a false perception however in illusion is real but it's made to be out to be something different than what it is
April
hope that helps
April
hallucination is an experience involving the apparent perception of something not present. illusion is a thing that is or is likely to be wrongly perceived or interpreted by the senses.
MH
like u see a rope and if you perceive it as a snake it's illusion
kitty
And if you feel like something crawling into your body(in reality such a thing is not happening)that is hallucination
kitty
I hope examples will make it more clear for you
kitty
and even hearing voices when no one has spoken is also hallucination
kitty

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Source:  OpenStax, Psychology. OpenStax CNX. Feb 03, 2015 Download for free at https://legacy.cnx.org/content/col11629/1.5
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