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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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gamma correcting a sinusoidal grating [psychophysics]

I am developing a stimulation setting wherre I present a sinusoidal grating to a subject. Because of the monitor gamma expansion by a factor of 2.2, I need to gamma compress my sinusoidal grating by a ...
André89's user avatar
3 votes
1 answer
220 views

Can a blind-from-birth individual experience vision or visual imagery during a Near-Death Experience (NDE)?

I recently watched a testimony in which a blind-from-birth individual described two NDEs they had had in which they supposedly were able to see with 20/20 vision (inside the NDEs). The person ...
Mark's user avatar
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0 answers
32 views

Functional/Cognitive Acuity/Manipulability

I'm trying to find an existing construct for what I refer to in my research as "Functional Acuity" (hereafter FA). The concept of FA is analogous to what one can see with v w/o one's glasses....
jackisquizzical's user avatar
0 votes
0 answers
36 views

Is the retinal image a picture? [duplicate]

I have some books on visual perception in which the retinal image in the human eye is described and represented (in pictures) as a "picture" or "visual representation" of the ...
Tony C's user avatar
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0 answers
34 views

Average number of neurons a signal travels through?

What is the average number of neurons a signal goes through before reaching the end? Although it may be naive, it seems that the maximum amount of neurons a visual signal, for example, that passes ...
Danny  Han's user avatar
  • 143
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0 answers
7 views

How to calculate latency between two different brain region in Steinmetz dataset?

I am new to Computational Neuroscience and recently, I came across to Steinmetz dataset and looking into the dataset, I had an idea of calculating the latency between two brain regions in terms of ...
Ammar's user avatar
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0 votes
0 answers
18 views

QUEST Staircase Resolution and Accuracy

I am flickering letters on and off to participants, controlled by a flicker rate which I am restricting to integer values. If I want to implement a QUEST staircase to determine the final threshold ...
Mark L's user avatar
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0 votes
0 answers
37 views

Do humans see rates of change of colour

On a computer, we measure colour numerically, as three values, say red, green, blue. While our eyes include detectors for red, green and blue (although these aren't exactly the same as the light ...
Thomas Anton's user avatar
3 votes
0 answers
31 views

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 ...
C. Almeida's user avatar
3 votes
1 answer
59 views

Which unit should be used to compare perceived spatial frequency of 2 different sized image? Cycle per image or cycle per degree?

I am interested in the topic of spatial frequency and its impact on face processing. I have been reading about previous studies that have used different spatial filtering thresholds for their stimuli. ...
gorgorotor's user avatar
-1 votes
1 answer
36 views

Is there a name or any research on white flashing behind the eyes?

I have encountered anecdotal evidence that sometimes when people meditate, as they progress to higher levels, they sometimes experience flashing white light behind the eyes. And I have also ...
Julius Hamilton's user avatar
3 votes
0 answers
13 views

Macaque V1 excitatory and inhibitory neuron tuning properties?

I am looking for tuning properties of excitatory and inhibitory neurons in V1 of Macaque (like orientation and direction selectivity), similar to results reported by Niell and Stryker (2008). Most ...
Luke Taylor's user avatar
2 votes
2 answers
76 views

Does the human eye have a muscle that if paralyzed would make us only see things that are in motion?

In "Kwantechizm", a relatively popular book written by a Polish physicist Andrzej Dragan, I read that chickens move their head so that they can see things that are not in motion, with the ...
d33tah's user avatar
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1 vote
0 answers
23 views

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 ...
FLSBob's user avatar
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3 votes
1 answer
78 views

Doubt about zero-crossings detection in the visual system

I'm currently reading the excellent book "Vision" by David Marr. In chapter 2.2 (ZERO-CROSSINGS AND THE RAW PRIMAL SKETCH), he explains a possible model for the physiological detection of ...
ИванКарамазов's user avatar
4 votes
1 answer
270 views

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

I see purple, violet, magenta, etc. as very similar shades and don't understand why. Consulting color wavelength charts like we see that purple (or violet) is about 400 nm. Consulting color mixing ...
Toke Faurby's user avatar
5 votes
1 answer
344 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 ...
მამუკა ჯიბლაძე's user avatar
2 votes
0 answers
109 views

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 ...
bigbrainboy's user avatar
2 votes
1 answer
585 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 ...
Probably's user avatar
  • 315
1 vote
0 answers
37 views

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 ...
WDUK's user avatar
  • 111
2 votes
0 answers
48 views

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.
user avatar
2 votes
1 answer
197 views

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 ...
nat's user avatar
  • 21
2 votes
1 answer
70 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 ...
HernanLG's user avatar
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1 vote
0 answers
67 views

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 ...
Name's user avatar
  • 11
3 votes
1 answer
34 views

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 ...
ivan866's user avatar
  • 153
1 vote
1 answer
79 views

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 ...
Amisha Kirti's user avatar
0 votes
0 answers
58 views

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 ...
Anonymous's user avatar
0 votes
0 answers
47 views

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 ...
Deschele Schilder's user avatar
2 votes
1 answer
174 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 ...
David Cian's user avatar
0 votes
1 answer
50 views

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 ...
le4m's user avatar
  • 103
4 votes
1 answer
50 views

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 ...
Jonathon's user avatar
  • 141
1 vote
1 answer
141 views

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 ...
Cotton Headed Ninnymuggins's user avatar
3 votes
0 answers
62 views

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 ...
Hans-Peter Stricker's user avatar
4 votes
1 answer
86 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&...
Marco Disce's user avatar
1 vote
1 answer
414 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 ...
LimeAndConconut's user avatar
1 vote
0 answers
47 views

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 ...
Eugen's user avatar
  • 111
6 votes
1 answer
2k views

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 ...
Dan D.'s user avatar
  • 163
4 votes
1 answer
121 views

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 ...
Siju George's user avatar
2 votes
0 answers
62 views

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 ...
TanZor's user avatar
  • 121
0 votes
1 answer
323 views

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 ...
gaspar's user avatar
  • 135
3 votes
0 answers
35 views

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/...
Johnoldinho's user avatar
2 votes
1 answer
138 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 ...
ak0000's user avatar
  • 123
2 votes
1 answer
97 views

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 ...
vvm32812's user avatar
1 vote
0 answers
22 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 ...
d1600552's user avatar
3 votes
0 answers
67 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 ...
user avatar
2 votes
0 answers
55 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 ...
Minkyu Choi's user avatar
2 votes
0 answers
52 views

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 ...
Mikhail Gaichenkov's user avatar
4 votes
1 answer
255 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 ...
Franklin Pezzuti Dyer's user avatar
1 vote
0 answers
128 views

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 ...
George Ntoulos's user avatar
4 votes
1 answer
191 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 ...
wisdom's user avatar
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