Questions tagged [vision]

For questions regarding the visual system, which serves to transduce light energy into neural impulses, or regarding visual perception, how we interpret such incoming visual information.

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How is 'purple' both ligt at one wavelength and the sum of light at two different wavelengths?

Consulting color wavelength charts like we see that purple (or violet) is about 400 nm. Consulting color mixing charts we see that purple is also the result of adding red (665 nm) and blue (470 nm) ...
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5 votes
1 answer
65 views

What causes this motion illusion?

There are some questions here about various optical illusions. I stumbled upon this one and would like to find out where does it belong. Wikipedia has a page about illusory motion that mentions ...
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Reducing pareidolia?

Going in the opposite direction and artificially increasing Pareidolia (the tendency for perception to impose a meaningful interpretation on a nebulous stimulus, usually visual, so that one sees an ...
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2 votes
1 answer
76 views

Is there any evidence that some people who claim to see auras around persons actually see them?

I have found that seeing "auras" is used for diagnosis of some neuropathologies. However, I wasn't able to find evidence that some people truly see what is colloqially known as auras. Is ...
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How does the brain know the difference between large distant objects and small nearby objects?

If you had two objects with words on them, one very large font and one very small font. The large font object is further away from you than the small font object, but you could see the detail on them ...
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2 votes
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While scrolling the web page interesting effect encountered with an image....is this optic inertia?

While scrolling this web page, interesting effect encountered with the image below. Is this optic inertia? The faster the scrolling, the more wavelike figures appear on three areas in the picture.
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1 vote
1 answer
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Slope of psychometric function too steep?

I am in a project where we are preparing a visual decision making experiment which requires participants to detect vertical grating in a patch of dynamic noise (the noise pattern is updated on every ...
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2 votes
1 answer
66 views

Sources on P1/N1 modulation with checkerboard probe

I have been able to find a lot of papers that modulate the P1/N1 component with a visual probe, usually a checkerboard presented parafoveally. I understand the basics of what I am reading, but I would ...
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Does the way we see the world in vision change with age? [closed]

I clearly remember a period in my youth where the world looked better, more colorful. Cartoons and videogames, drawings and pictures seemed higher resolution. Around the age of 15 I started noticing ...
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3 votes
1 answer
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Meaning of a phrase '... reciprocal of neutral density value required arranged on an inverted scale'

The article paramount for my research seems cryptic. It is for visual perception (psychology) and was written 45 years ago. There are a number of sentences hard to 'decypher'. 'reciprocal of neutral ...
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1 answer
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Why do I often feel that someone's eyes are at me from a far off distance?

Often when I'm in a public place, I get the intuition that someone is looking at me even when I don't turn or look in that direction or move my eyes. I just have a strong feeling in my heart that ...
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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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2 votes
1 answer
82 views

What is the difference between recurrent and feedback synapses?

In the paper proposing recurrent convolutional neural networks (RCNN), "Recurrent Convolutional Neural Network for Object Recognition", it is stated that "recurrent synapses typically ...
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1 vote
1 answer
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Is there a word that differentiate between image rotation and image translation?

For an image with an object (e.g., a cat) and its slightly tranlsated image (or its flipped image), an average person can instantly recognize that the objects in the both images are the same (i.e., a ...
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SAD Therapy Light Specifications?

I keep running into alternative theories and facts about what specification of light to use in sun lamps for light therapy treatment. Many actual afflicted people seem to just swear by just pumping as ...
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1 answer
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Why can’t my eyes gaze around at a constant rate?

I’ve wondered about this for quite a long time, but never thought to ask it anywhere: I’m assuming most people know what it’s like to watch a bird flying by, you can steadily concentrate as the bird ...
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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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4 votes
1 answer
71 views

What degree of control do we have on eye movements?

When something "new" and "interesting" enters our visual field it can usually happen that our eyes move toward the new target. How "intentional" and "controllable&...
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1 vote
1 answer
124 views

How to view or download an open access article from ARVO journals?

I would like to read or download this ARVO Journal's article, but I just cannot find any button on the website with this functionality: https://jov.arvojournals.org/article.aspx?articleid=2139676 I ...
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1 vote
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Requirements and development of depth and spatial orientation sensing

I'm trying to understand from the signal processing perspective how the perception of depth and the ability of spatial orientation is calculated by our brains. One possible explanation seems to be ...
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6 votes
1 answer
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Why is the occipital lobe behind instead of in front?

These are regions of our brain: Our eyes are in front below our forehead, however, the visual area Occipital Lobe is behind. Are there any biological reasons for this? why shouldn't Occipital Lobe be ...
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1 answer
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Do people who experience heautoscopy become unable to see their reflected image in a mirror?

I understand that people who experience autoscopy can see their body image outside them without a mirror. I had read many years back in a paper that people who experience the inverse phenomenon called ...
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2 votes
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Parallel target search and serial blank search

Wolfe (1991) reports an example of a search that seems to be parallel for target trials and serial for blank trials: Here's another example from Wang et al., 1994 Strangely, In Treisman's seminal ...
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1 answer
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Equalize/balance brightness and saturation of different colors using RGB (across various monitors)

We want to present different colors to participants in an online experiment (in an HTML/CSS-based application, hence we'll use RGB values). More in specific, we ...
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Objectively defining the image parameters for facial detection, recognition, and identification in digital imagery

Axis communications have given guidelines on minimum operational requirements of a camera to allow a human observer to identify, recognise, and detect human subjects (https://www.axis.com/en-ca/...
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2 votes
1 answer
92 views

Can eye tracking be used as a form of biofeedback?

I'm an occasional meditator and I've noticed that conceptual thought often produces eye movements, and I'm curious if anyone has tried using eye movements as a form of biofeedback. The Muse headset ...
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2 votes
1 answer
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Why does an image seem smaller or larger through a pinhole when viewing with human eye

I was chewing gum when I took the Trident gum wrapper and rolled it into an open cylinder with a diameter of about 1.5mm (give or take 0.15mm). When I look through the gum wrapper (I have to put it ...
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1 vote
0 answers
18 views

Why does an image seem smaller through a pinhole when viewing with human eye

I was chewing gum when I took the Trident gum wrapper and rolled it into an open cylinder with a diameter of about 1.5mm (give or take 0.15mm). When I look through the gum wrapper (I have to put it ...
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3 votes
0 answers
54 views

How does number sense develop in blind people?

From what I understand about number sense and numerical cognition, the visual system is heavily involved in the approximate number system and the object tracking system, which are at the root of ...
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2 votes
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40 views

Retinotopic mapping to higher visual cortex

I know visual stimuli from retina presented in Cartesian coordinate is mapped to V1 as a form of polar coordinates. Wikipedia, Scholarpedia But I wonder whether this spatial representation in polar ...
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2 votes
0 answers
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Accuracy of visual distance and size perception

Generally speaking it is known that human observers’ perceptions of distances in depth are generally inaccurate. I guess that the accuracy is sometimes a very large degree. To be more specific I am ...
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4 votes
1 answer
152 views

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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1 vote
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Decussation of Cranial Nerves

Which cranial nerves decussate apart from the few nerve fibers of the optic nerve that do and how to easilly remember the cranial nerves that do? Here is a paper for the Trochlear Nerve But I have ...
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4 votes
1 answer
128 views

Visual Cortex percentage

Could somebody help please in providing some research papers or a resource book that states how much the visual cortex occupies of our cortex? I am trying to find some reliable source but I couldn't ...
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3 votes
2 answers
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Why is deltaE not used as a measure of error?

I've recently read a few articles pertaining to visual memory. Most of them (e.g. Bays et al., 2009 use the continuous color recall task where they ask participants to recall the color of an object by ...
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Is there a double dissociation between face and object processing?

We know of the condition called prosopagnosia in which the processing of faces is impaired. Is there a condition in which the processing of faces is intact and the processing of objects is impaired, ...
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3 votes
0 answers
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Relaxing your concepts in meditation

I am using the app Waking up from Sam Harris. A lot of his guided meditations tell you to perceive the world as the raw data of experience, instead of perceiving objects and concepts. To illustrate ...
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1 vote
1 answer
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Is the visual cortex of a newborn baby immediately capable of object detection or is this skill learned over time, and if so, how?

Is the visual cortex of newborn babies right off the bat capable of making sense of raw visual data, for instance, converting the constant stream of raw RGB images perceived by the eyes into a ...
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3 votes
0 answers
53 views

Is there some cognitive test besides (visual) working memory in which some animals are superior to humans?

Assuming the research of Matsuzawa et al. (2007) (see also BBC video (2013)) isn't misleading, are there any other cognitive areas where chimpanzees (or other primates) have been observed to surpass ...
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3 votes
1 answer
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Is there a foveal explanation for the duck-rabbit illusion?

Myself when I look at the duck-rabbit image, I see a duck if focus on the left (i.e. the beak) or a rabbit if I focus on the right (the nose). Is this how it works for most people, i.e. is the foveal ...
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3 votes
1 answer
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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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1 vote
1 answer
52 views

How are ocular dominance columns monocular despite binocular complex cells?

Orientation columns in the primary visual cortex are known to have (mostly) simple cells in layers 4 and 6, and (mostly) complex cells in layers 2,3 and 5. Orientation columns spanning an entire range ...
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2 votes
1 answer
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Differences in reaction time on visual tasks with and without binocular disparity ques?

Have there been any studies done that test the reaction time to vision processing tasks with and without the benefit of binocular disparities? I have been wondering how much depth information (such as ...
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2 votes
1 answer
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Is there any evidence for or against the existence of neurons that encode surface slant in vision?

In the way orientation columns display selectivity for various edge orientations projected on the retina which is then repeated at various angles in a localised region of the cortex. I am wondering ...
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6 votes
1 answer
1k views

Are scintillating scotomas really caused by cortical spreading depression? If so, how is this known to be true?

I have just read about a visual effect called a scintillating scotoma. Many variations occur, but scintillating scotoma usually begins as a spot of flickering light near or in the center of the ...
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1 vote
1 answer
410 views

Unilateral vision in split brain subjects

I am just beginning to learn psychology and came across concept of split brain. I was wondering if a person has only left eye working and has their corpus callosum cut, would they be effectively blind ...
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3 votes
1 answer
46 views

Fit a psychometric function when the maximum is not 100% (not because of lapse)

I found that currently the form of psychometric function assumes that the proportion correct lies between 0.5-1 given the range of stimulus level, but how to fit a psychometric function when the ...
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4 votes
2 answers
1k views

If the optic nerve transmits to both hemispheres, how do split-brain experiments work?

From what I understand, the optic nerve of each eye transmits information to both hemispheres of the brain. This is unlike other sensory and motor information, where (for example) the right hand is ...
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4 votes
0 answers
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Is the perception of drawings an acquired skill?

Most descriptions of visual perception explain how our brains interpret incoming visual stimuli (via feature detection, monocular depth cues, etc.). They then assume that the same process works for ...
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