Questions tagged [optical-illusion]
For questions relating to optical illusions, how our perceptual and cognitive mechanisms give rise to them, the neurological basis of perceiving optical illusions and general queries relating to optical illusion research.
31 questions
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How can flashing horizontal black lines appear colored?
https://www.instagram.com/reel/DBzjm20uO3g/
In this video we see rapidly flashing horizontal black lines. But some of the lines appear red, green, yellow or blue. Why? The effect disappears when you ...
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Is there a Mach band on a step edge or not?
Recently, I've been reading about the Mach band effect and there is a particular case which is confusing me a little bit, since people don't seem to agree on what actually should be perceived.
It is ...
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Water rushing away causing a pronounced sense of movement -- is there a name for this?
I had never heard of this happening before nor can I find anything online but this happened to me years ago, did not try it again and I wonder if once you realize the illusion it no longer works.
As I ...
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Which waveform for photic stimulation should be used to generate SSVEP in a narrow band around desired frequency
I am trying to build my own flickering light stimulation device. The light source will be a COB Red LED cluster (~627nm) (like one of these) with brightness controlled using Pulse Width Modulation ...
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How does curvature of our eye affect our perception of the world?
The front part of the eye which can allow light to enter is a bit curved, so shouldn't this cause us to see a curved distorted version of reality when it is really not there? Is there any way to ...
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Mirrors/optics and physical adaptation of the eye
Is it possible to use a clever combination of lenses and mirrors placed between your eye and a screen 1m away from you to make the eye react to the screen as if it were 20m away from you?
What I'm ...
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The differences between sensory distortions and hallucinations
So, the way I've understood it, "sensory disturbances" can be categorized as follows:
Any sensory experience that isn't real goes under "sensory disturbances" in this diagram. If ...
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When one wiggles a dark object with bright letters &c on it, the letters appear to move, floating in the plane. What is this optical illusion called?
I stumbled upon this phenomenon in the 90s, when I was still a kid. I noticed that in the evening under indirect artificial lighting the red letters on a blue book cover (I think it was a Pink Panther ...
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Is the perceived flexibility in this picture (when moving it) related to the perceived curvature when it's not moving?
Look at this picture:
All squares are of equal size but when you look at the picture the horizontal and vertical bands they constitute seem to be curved. When you move the picture up and down the ...
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Non-serotonergic hallucinogens
According to this article, agonism of the 5-HT$_{2A}$ is necessary for hallucinogenesis. Now, not all hallucinogens are primarily serotonergic, but does there exist hallucinogens that aren't at all ...
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A new kind of optical illusion?
By accident, I stumbled over this optical illusion:
It is not a strong one, and maybe you don't experience it, but I see the size of the circles in the second last row decrease from left to right. I ...
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Multistable perception with three possibilities
I know that multistable perception refers to the phenomenon that occurs when we look at an ambiguous image like a Necker Cube or some sort of positive/negative space art, and we can’t perceive both ...
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Is the Thatcher Face Illusion only limited to face recognition?
The so called Thatcher-Illusion has been documented not only on humans but also in some monkeys.
However I can't find literature clearing out if this effect only applies to face-recognition.
What ...
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To what category of optical illusions does this image belong?
To what class of optical illusions does the below image belong? The diagonal lines are parallel, but because of the context, the longer of the two appears bent.
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Why do we see shadows in the following black-and-white optical illusion?
How does neuroscience explain the following optical illusion? Look at tiles. You will see spots of shadow near all corners. The shadow will be missing from some corners very near the center of your ...
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Is quick left brain vs right brain test fake?
When I saw it at first she did rotate to the right.
With some mental effort I could make her rotate either way in half rotations where it looks like she dances not rotating in my minds eye, but I ...
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Due to Gestalt Psychology, is the face an illusion?
Gestalt Psychology maintains that we perceive a whole from parts, and that we fill in missing gaps. The "whole" we perceive is more than the sum of parts we perceive - it also involves what our minds ...
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Is there a waterfall visual after-effect with discrete inputs?
If you watch a waterfall for several seconds and then suddenly change your gaze to a fixed object it appears to briefly move upward.
But if instead you're looking at a scrolling LED marquee sign, ...
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Why can I see the number only when I don't look directly at it?
I've recently found the following image:
I can easily see the "17" in the image if I'm scrolling and (much less easy) when I move my eyes and don't look directly on it. Why is that the case?
In case ...
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What is the difference between apparent motion and apparent movement?
A definition for apparent movement is:
The perception of movement produced by stimuli that are stationary but are presented first at one position and then, at an appropriate time interval, presented ...
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Is the Rubin Vase illusion an example of inattentional blindness?
Generally, people looking at an example of a Rubin Vase see either the vase, or the faces. The brain seems to make a decision on which one is being viewed, but both cannot be focused-on at the same ...
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How much our visual limitations are instrument(eye)-based, and how much are they brain-based?
Are the limitations to our vision like the field of view and singular focus entirely based on the limitations of the eye?
It seems like it's possible to feed an artificial signal into the brain ...
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What happens in your brain when you see a dinosaur in this stenographic image?
You might have come across stereographic Images like the one shown below (found here):
What happens in your brain when you observe the dinosaur? (as you put your face on the image by touching your ...
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How come we see a line when there isn't one in this picture?
I got this picture I generated myself and I don't understand how come we can see two diagonal lines when, I think, there is no actual lines.
Zooming in:
Center: Just another 2px wide square…
After ...
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Optical illusions : human universal vs environmental influences [closed]
It's well known today that the susceptibility to optical illusions are influenced by the environment: multiple studies with the Müller-Lyer illusion conducted in Zambia proved this environmental ...
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What color is this dress? -- And why do some see it as white and gold and others see it as black and blue?
Here's the dress (and keep reading, this is actually a serious question):
This question about this image has apparently become quite a rapidly spreading meme on the internet. And after conducting my ...
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aftereffects of auditory adaptation
Adaptation is a very robust feature of sensory processing: when a stimulus is displayed for a prolonged period, or repeatedly, the neural response to it will diminish. This process creates a local ...
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What's the explanation of this optical illusion where many coloured arcs radiate from a central point?
I saw the image below on facebook. At first, I thought it's a GIF animation since it doesn't appear static but it turned out to be a static JPEG image and the apparent motion is caused by the brain. ...
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Distortion of faces presented serially in peripheral vision
I've kind of already answered this question for myself, but I can't resist sharing it anyway. Please feel welcome to add anything you can in another answer.
Stare at the cross in the middle and try to ...
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Is this some sort of soft-coded Grapheme-Color synethesia?
I just found this remarkable optical illusion:
To do:
Fixate your gaze on the center of one of the figures and stare at it for some time (20-30 seconds) while it cycles (without moving your eyes). ...
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Can prolonged neural adaptation lead to HPPD?
The human brain adapts to a constant stimulus of our neural system. For instance, if we ride a train and look out of the window for a long time and the train stops, we have the feeling of slowly ...
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