Questions tagged [perception]
258 questions
94
votes
4 answers
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 yellow pigment reflects only yellow light, but the…
David A.
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79
votes
5 answers
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 make a superposition waveform, which is obtained…
chharvey
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79
votes
8 answers
Does quantum mechanics play a role in the brain?
I'm interested in whether the scale of processes that occur in the brain is small enough to be affected by quantum mechanics. For instance, we ignore quantum mechanics when we analyze a game of tennis because a tennis ball is much too large to be…
QCD_IS_GOOD
- 7,145
70
votes
6 answers
How does light combine to make new colours?
In computer science, we reference colours using the RGB system and TVs have pixels which consist of groups of red, green and blue lines which turn on and off to create colours.
But how does this work? Why would certain amounts of red, blue and green…
Isky Mathews
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34
votes
11 answers
Why can't the human eye focus to make blurry photos/video clear?
The human eye focuses by flexing the lens, changing its focal length. When we switch from looking at a near object to a far object, our lens flexes, moving the focal length such that the near object is out of focus and the far object is in focus. …
Ryan_L
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21
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11 answers
Are colors grounded in physics or are they a matter of human perception?
My father was colorblind, and I always wondered if colors were a matter of physics or if different colors are just a human way of describing and differentiating our visual perception of the world?
For example, is the color blue by nature blue, or is…
user163693
- 319
20
votes
9 answers
Why do objects appear smaller when viewed from a distance?
Yes, I know all about perspective (I'm an artist). I even have some basic knowledge of descriptive geometry. I know how it works. My question is more about why it works.
I have a sneaking suspicion it has something to do with the curvature of…
Ricky
- 641
19
votes
5 answers
Musical notes and colors of a rainbow
I have wondered that in an octave in piano there are seven primary notes, and also we observe mostly seven primary colors of a rainbow. I know we perceive logarithmically, that means we only care about relative differences.
Is there any relation…
17
votes
2 answers
Why can't the human voice produce a Shepard tone?
Audio of a shepard tone on youtube.
So what is a Shepard tone?
A Shepard tone, named after Roger Shepard, is a sound consisting of a
superposition of sine waves separated by octaves. When played with the
base pitch of the tone moving upward or…
Nilay Ghosh
- 1,292
17
votes
7 answers
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 for the future. So it is generally thought that…
Eric
- 831
15
votes
2 answers
Why does the sky suddenly look gray through this window?
I am looking to the windowed roof of my building, and I notice that the sky, which has few white clouds, sometimes looks completely gray, as if there was a huge cover of gray clouds, but there are not.
By observing it and waiting for the change to…
PhilDenfer
- 253
14
votes
7 answers
Are human eyes interferometers?
It seems like 2 eyes is enough “wetware” to do interferometry inside brain. Can you definitely see some reason why this could not be happening, or some way to test if it does happen?
Euphorbium
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14
votes
6 answers
Why do objects appear smaller when farther away?
Why does the apparent size of an object change when it is farther away from me compared to when it is closer to me?
Can someone perhaps explain this through an optics perspective?
Your neighbor Todorovich
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13
votes
10 answers
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 way?
(Answers like we can take time as an…
TMS
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13
votes
2 answers
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.
When it comes to the Moon on the other hand, the…
Sejanus
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