Questions tagged [perception]

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1answer
63 views

Human colour perception – summary needed

I am a graphic designer and I really want to have knowledge about human colour perception but the longer I am looking for and the more I read the harder this topic seems to be. Physics is not my ...
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4answers
13k views

Why does a yellow object turn white under a yellow light? Shouldn't it turn yellow instead?

Recently I was eating a yellow rice for lunch in a restaurant with only yellow lights. But the rice looked white! I was intrigued by this because I always thought it should look yellow since the ...
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2answers
43 views

How does human eye perceive distances? [duplicate]

In case of myopia a parallel beam of light appears to come from the far point of the eye when we use corrective concave lenses. But we do not perceive it as it is coming from the far point, instead we ...
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1answer
57 views

Why do things look bigger when you're far away?

When I'm on my bed looking outside the window, the trees in the park which is quite some meters away looks big and closer than the actual distance. But when I get up from my bed and go and see it ...
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1answer
28 views

Spectral sensitivity of the human eye -

Following the question: Sensitivity of eye I would like to make sure what these % says about? Is it the ability to colour detection? The similar stuff is here: http://www.giangrandi.ch/optics/eye/...
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3answers
58 views

A single eye vision vs normal vision [closed]

I am trying to understand the basics of human vision and looking for a model to see pros and cons of a single eye vision vs two eyes vision. Generally my interest relates to a basic project in a ...
1
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3answers
67 views

Noise perception by humans - one vs two of the same noisy appliance - will the noise be “double”?

If I have a clothes washer in a room versus two of the same machine making the same noise, will the noise level be perceived by humans as twice the level it was before? I'm pretty sure sound is in a ...
15
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5answers
4k views

Why do we remember the past but not the future?

The question is sometimes referred to as the "psychological arrow of time" (Hawking, 1985). Here the past is understood as a moment or time when the entropy of the universe was lower, and contrarily ...
7
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3answers
359 views

Effect of layout on text visibility [closed]

My college recently switched to whiteboards. Though writing on a whiteboard with a black ink sounds similar to the conventional way of writing with white chalk on a blackboard, it feels very different....
1
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2answers
127 views

Colors of the Earth from space, an “average” of particular emitters?

When we're say about 100 km above Earth's ground and look down to it and see the Amazonian region as green, is this green color a sort of "average" of greens from trees from that forest or is the "...
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0answers
43 views

Why don't we see/feel charged particles, penetrating our brains/retina?

If we see tracks in bubble or Wilson chamber, it means that particles are everywhere and can leave tracks in gases and liquids. They can also penetrate concrete of the building levels in the lab. So ...
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0answers
42 views

Could this work as a way to make 2D appear 3D? [closed]

So there is an effect where if you close one eye while watching a 2D movie, it appears slightly more 3D. This being because your depth perception no longer has the cue from two eyes. (As an ...
0
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1answer
36 views

On seeing and especially in the dark

Our retina detects the change in the electromagnetic field due to the jiggling of the atoms surrounding us as I understand the seeing process. In the total absence of a light "source", however, why ...
14
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10answers
851 views

How to explain (pedagogically) why there is 4 spacetime dimensions while we see only the 3 spatial dimesions?

I have been asked this question by a student, but I was able and in the same time incapable to give a good answer for this without equations, so do you have ideas how one can explain this in a simple ...
4
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1answer
47 views

Astronauts in spacecraft, they have to circle the earth many times a day, do they also have the illusion of the moon?

Astronauts in spacecraft, they have to circle the earth many times a day, do they also have the illusion of the moon? I don't think they have, because according to the theory, the illusion of the moon ...
3
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2answers
457 views

Why might Roger Penrose argue that Godel's incompleteness theorem(s) suggest that consciousness is non-algorithmic? [closed]

This past March, when I called Penrose in Oxford, he explained that his interest in consciousness goes back to his discovery of Gödel’s incompleteness theorem while he was a graduate student at ...
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0answers
39 views

Why does the wind close doors?

Assume you have two rooms, both with holes in the wall (more commonly known as open windows), which connect each room to the exterior. The two rooms are connected, but the connection can be closed by ...
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0answers
47 views

How to explain this thumb experiment?

Close your thumb to your eyes and align your eyes, thumb and moon. Then focus your eyes on your thumb and watch the moon behind your thumb. You will find that the moon becomes small! Remove your thumb ...
1
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1answer
540 views

How can a loud sound's perceived pitch differ from its predicted value from only its frequency?

Sparknotes $\qquad $ Quora answer by Mr. Kennan Hye BS (Engineering), MEng. (Acoustics): Pitch is sometimes defined as the fundamental frequency of a sound wave (i.e. generally, the lowest ...
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5answers
5k views

Why don't humans perceive sound waves as twice the frequency they are?

I was reading about how at how acoustic beats work. If we combine two waves with frequencies $f_1$ and $f_2$ and unit amplitude, their combination is $$ \begin{align} A &= \cos\left(2\pi f_1x\...
6
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2answers
457 views

What frequency is the scratching of finger nails on a blackboard?

This is the frequency/intensity that sets my teeth on edge. Does anybody know what frequency (roughly) it is? I am guessing it is near the top of normal human hearing, 20kHZ, but I'm not sure if ...
8
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2answers
225 views

Why does the additive color model use red, green and blue instead of yellow, green and violet?

Long cone cells in the human eye are most sensitive to 570-nm wavelengths which are more like spectral "yellow" than spectral "red" and short cone cells are more to 440-nm wavelengths which are more ...
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0answers
29 views

Red and orange lights appear to be blinking [closed]

Why does the red and orange lights appear to be "blinking" and the blue and green lights appear to be still? The lights on this hula hoop are always stagnant, and in every picture this exact same ...
0
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2answers
55 views

Perception of time [duplicate]

A video I came across in youtube recently had mentioned how Einstein perceived time. It said he thought of all moments, the present, past and future to exist together and how it is not like one ...
3
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3answers
808 views

Why do we perceive time?

Since everything (at least what we observe) is travelling through the time in the same direction and speed why do we even perceive the time? Of course, there is the time dilatation, but it is ...
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0answers
23 views

Visualizing higher dimension [duplicate]

Why can't we visualize Higher dimensions greater than 3? Is it just because the dimensions doesn't exist (Certainly I know that space-time is four dimensional) or any other physical reasons.
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3answers
118 views

What had Feynman meant when he told nobody understands Quantum mechanics? What do we mean by understanding Quantum mechanics?

What had Feynman meant when he told nobody understands Quantum mechanics? What do we mean by understanding Quantum mechanics?
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2answers
65 views

Why do we see things upside-down when we’re upside-down but not a camera?

If I do a handstand, everything looks upside down (which is originally what we see if we’re upright but the brain switches this). I assume this is because the change in how light rays enter our eye. ...
2
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3answers
80 views

Virtual images - Work of a brain or work of a lens?

I am just a high school student trying to self study, so please excuse me if this question sounds silly to you. Many people tell me that virtual images are formed when two rays that are diverging ...
3
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2answers
2k views

About our voice transferred into electrical signal

I know when we speak to the microphone, the pitch of our voice cause the vibration of magnet in the microphone, thus causing generation of different voltages of electrical signal. But my question is: ...
4
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2answers
213 views

Human perception of temperature

I had the following thought experiment recently: Suppose we have a vibrating plate for which we can tune the amplitude and frequency of vibration, and imagine we hold a finger against the plate. For ...
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0answers
34 views

The rise of BCI

If EEG and MEG are measuring different aspects of neural oscillations, why can't we measure the combined signals as a whole, when we are doing the same for higher frequencies? Why did the us navy ...
2
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1answer
278 views

Why hot soup is tastier than cold soup? [closed]

My physics teacher recently asked me this question. Can anyone answer the question?
-1
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1answer
97 views

What is this optical illusion in which airplane propellers appear to rotate backwards? How is it explained? [duplicate]

This airplane's propellers are both rotating anti-clockwise. But as you see, they are seem like rotating clockwise seen from front (nose) side. This phenomenon is known as optical illusion. My ...
5
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3answers
1k views

When does the wagon-wheel effect occur?

Sometimes you see a video of a fan or a propeller spinning very fast, and the apparent rotation is distorted. The fan can appear to be moving in the opposite direction of rotation, or even stationary. ...
0
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1answer
101 views

Does intuition really matter in the beginning of any new physics course? [closed]

Encountering some new courses like quantum mechanics, theoretical solid state physics and some other courses made me feel dumber than I ever felt.  Basically, I'm that kind of students who hate to ...
0
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1answer
31 views

Feeling sound; frequency and volume

How loud and "low" must a sound be in order for one to feel some physical sensation in response? I've read that below certain frequencies humans can be expected to "feel" sounds in their chests, and I ...
1
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1answer
39 views

How do we hear harmonics and how does it affect audio fidelity?

First and foremost, do we hear a sound wave as a sum of all the individual harmonics, at the fundamental frequency, or do we hear all the associated harmonics above the fundamental frequency and ...
5
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1answer
2k views

Why does the sky look darker blue directly above me, but get lighter in the distant sky?

it seems that the sky looks a bit darker right above me, but if I look into the distance, I see a paler blue.
74
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5answers
7k views

Why can we distinguish different pitches in a chord but not different hues of light?

In music, when two or more pitches are played together at the same time, they form a chord. If each pitch has a corresponding wave frequency (a pure, or fundamental, tone), the pitches played together ...
0
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1answer
693 views

Why don't we see inverted image while wearing spectacles? [closed]

We know that the lens in our eyes forms an inverted image on retina and brain reverses it to give the correct image. But when one wears specs the image would get reversed twice so we should see things ...
2
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1answer
195 views

How does the Many-Worlds Interpretation of Quantum Physics relate to Consciousness? [closed]

According to the Many-Worlds Interpretation of Quantum Mechanics, each quantum event causes the world to "branch" into a superposition of outcomes. How come "my" consciousness only chooses one of ...
0
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2answers
213 views

Why does physics “make sense”? [closed]

I was wondering if anybody had an explanation for why physics makes so much sense to us humans. In physics, many concepts just seem to make sense to me, but I cannot explain why. You may say that this ...
1
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2answers
301 views

How many eyes are needed to see a four-dimensional world? [closed]

If a four-dimensional world were to exist, how many eyes would a creature minimally need to see it (in three dimensions)? Three? Four? (Bonus question: how should these eyes be spatially configured?)...
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4answers
8k views

Why does the human body feel loud music?

I was sitting close to a speaker and I could feel the sound coming from it all over my body, especially in my heart, and it pounded with the loud beats of the music. Was my heart pounding because of ...
8
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2answers
606 views

Why does the moon appear fairly flat to a naked eye?

When I look at the regular ball picture the "edges" appear somewhat darker. Here's a random image I just found on image search :) Image source and that's how I can tell it's "round". Or so I assume. ...
2
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1answer
140 views

Why do I see discrete images when moving an object in front of a screen? [closed]

I observed this while doing my homework. I have a habit of shaking my pen between my fingers vigorously while thinking something. My PC's screen is right in front of me (on my study table itself). ...
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1answer
42 views

EM spectrum and sense of sight

If we cant see all the spectrum does this mean that maybe exist objects we cant perceive? or it just the colors we cant perceive?
3
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1answer
652 views

Do we hear anything special when the beat frequency is in audible range, but the sounds producing the beats are not? [duplicate]

When the beat frequency is very low, we hear periodic maxima and minima. Our ear cannot perceive a on-off like sound when its frequency is more than 10 Hz. So, beat frequency in audible range will not ...
-1
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2answers
68 views

Perception of curvature of human eye [closed]

How are human eyes able to detect the different curvatures of surface ? Basically how are the human eyes able to differentiate between a plane surface and a convex or a concave surface?