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34

It is not meaningful to talk about your brain processing something as 'right-side up"' or 'upside-down'. The 'images' in your brain are just collections of neural activations, and not actual pictures. Thus they cannot have an orientation. The only meaningful way to test your question is to try flipping the input the brain receives and seeing if it can cope. ...


16

I think part of what makes this question confusing is the use of expressions like "what the eye sees", "what the brain sees" and "what the frog's eye tells the frog's brain". Nobody sees anything except the experiencing subject. When one stops thinking that the brain (or some visual-system part of the brain) observes the image on the retina, then the ...


16

At least for images (I don't know of such a result tested on videos) for a given resolution, there is an optimal display size (assuming constant viewing distance. otherwise, display size should be measured in angles from the viewers point of view). In a paper from 1989, Peter Barten provided a formula to compute this effect [1]. The gist can be seen in the ...


15

Treisman & Gelade's Feature Integration Theory suggests that we are able to process an entire visual scene in parallel at the level of individual features. For example, in a visual search task, the time required to find a blue circle in a field of red circles is independent of the total number of circles. However, focused attention (typically foveal) is ...


15

One of the main reasons related to the 'Gestalt principles' Law of Proximity Objects near each other tend to be grouped together. Law of Similarity Similar items tend to be grouped together. Law of Closure Objects grouped together are seen as a whole. Law of Continuity Lines are seen as following the smoothest path. Law of Common Region Items in similar ...


15

Your question is referring to display polarity. A positive polar display consists of dark letters on a light background, a negative polar display consists of light letters on a dark background. Polarity by itself is independent of text-to-background contrast, as you rightly state. Generally, positive polarity facilitates performance (e.g. Buchner & ...


14

I think you are succumbing to the homunculus argument, the fallacy that there is some sort of image in the brain for someone to view. There is no magical theater in your head where what is incident on your retina is projected. All you have in your brain is complicated patterns of neural activity, there are no images and nothing to view. However, these ...


13

As @Gray mentioned, the philosophical problem you are interested in is known as the inverted spectrum. Unfortunately, @Gray's claim about no empirical difference is not exactly true. As @ChuckSherrington pointed out, we can have differences in color perception due to brain lesions, but this is cheating in way. We don't have to go this far, we already have ...


13

First, it is not only your intuition - there are many experimental results showing that we first perceive the gist of scenes (for example, is it outdoors or indoors?), then the major parts of it (was there an animal, or a human figure in it?) then more and more details (is that figure male or female? what is her expression?) [1] [2]. Note, however, that it ...


13

Usually, for something to be 'real', we want it in some reasonable manner to be objective or (because that is extremely vague) at least very consistent across subjective observers. Unfortunately, colour does not satisfy this. Physical basis. As explained very well by @Stop_forgetting_my_account: Physics does not have colour, it just has a continuous ...


12

There are two related reasons, I believe for this: Relationship and connection. When things are aligned, we see then as connected and related. Nature does give us the guidance for things that are related and connected in other ways, but often by a degree of alignment or similarity. In UX terms, we indicate the relationships between items by positioning and ...


12

Yes, this scenario is possible, occurring with certain cases of brain lesions in specific areas of the visual cortex, the fusiform, lingual and posterior parahippocampal gyri. These areas are analogous to what is referred to in primates as V4, or the 4th visual cortex, and are known to be involved (at least partly) in the perception of color (though see ...


12

I basically agree with @Nick Stauner, but I want to add another important aspect, namely the gradient of photoreceptor densities in the human retina: In the fovea there is a sharp peak in cone density compared to more eccentric regions, as described in Curcio et al. (1990) and see the following graph obtained from Web Vision: The cones have a different ...


11

The human eye is an interesting device. One of the most amazing things it does is to adjust for the brightness, and it can do so over 10 orders of magnitude. From a signal processing perspective it can be explained as follows: There are a few different ways that this is done, but the most basic way is a high pass filter, with a cutoff of about .25-.3 Hz. ...


11

Basically, the retina contains two different kinds of receptors: rods and cones. Cones are concentrated in the fovea and activate ganglion cells more discretely than rods. Rods are more interconnected by horizontal cells (if I'm not mistaken...), so multiple rods can often activate the same ganglion cell, whereas each cone is more likely to have its own ...


11

You may want to read Meaidi et al (2014). They obtained dream reports from congenitally blind, late blind, and matched sighted controls. To quote the abstract, they found: All blind participants had fewer visual dream impressions compared to sighted control participants. In late blind participants, duration of blindness was negatively correlated with ...


10

It's essentially shot noise. In optics, shot noise describes the fluctuations of the number of photons detected (or simply counted in the abstract) due to their occurrence independent of each other. This is therefore another consequence of discretization, in this case of the energy in the electromagnetic field in terms of photons. In the case of photon ...


10

There's a general discussion of speed reading methods on Wikipedia, but let's look at some specific articles and see what they say about reading speed and comprehension. Bell's review of the reading speed and comprehension literature In Bell's (2001) review of the empirical literature, he makes a number of points, which seem reasonable to me: A few ...


10

Short answer: there appears to be a whole range of ability at the task of mental visualization. Based on what I have found on the Web, your own level of ability is fairly unusual. Your friend's level of ability, by contrast, seems to be fairly common. Sources I found on this were fairly sparse, though, and my conclusions should not be relied on too heavily. ...


10

The source I have quoted below gives an example of the following stenographic image:- Is this perception a particular trick that my eye performs or is it processing the visual data in an alternative way? Stereograms can be viewed as three-dimensional images by providing two side-by-side views of a three-dimensional scene, rendered from slightly ...


9

A good place to start for a high level understanding of all perception and action is Jaoquin Fuster's perception-action cycle. As he says, it's a "cybernetic cycle linking the organism to its environment". He describes two moieties of the brain, posterior sensation moiety, and the anterior behavioral moiety. Information cycles between perception, ...


9

People who are unable to perceive stereoscopic depth typically only perceive information from the dominant eye. Failure to perceive stereoscopic depth is usually caused by conditions where the eyes do not converge properly (e.g., strabismus). If left untreated, it is not possible to develop the necessary correspondance between the two signals from either ...


9

Probably. What you mentioned in your question is called retinotopy. There is a mapping between locations on your retina and areas on your cortex. As you go further up the visual processing streams, the mapping gets more complex and the patterns would be less obvious. Here's an image of from a 1988 paper in the Journal of Neuroscience (Tootell, et al.). It ...


8

The fact that the image does not appears upside-down has to do with the way visual information is processed in the brain. In his book, Jeff Hawkins argues that the low-level visual features on the retina (being upside down, distorted, and changing rapidly) are lost in the process of forming invariant representation. And it's those representations that we ...


8

The Wikipedia article no longer makes reference to the phenomenon that you quote (to my inspection), so I'm not entirely sure if that assertion was edited out as an inaccuracy on someone's part. I did find some information on visual perception and high frequency flicker that might point to some of the significance of the 60 Hz refresh rate of a monitor. At ...


8

Well for one, the first neurons to decode this symbol are orientation neurons, in V1 of the primary visual cortex. So some neurons have enhanced firing for say a 45 degree angle, and neighboring neurons for a 46 degree angle, and so on. Higher up the processing stream groups of neurons respond to shapes, that are a conglomerate of the orientation lines. Then ...


8

This is a type of illusory motion (or motion illusion) called the Enigma Illusion. The cause of motion illusion in general is not well understood, but research suggests that there may be slightly different reasons for the different types of motion illusions. A common theory is that particularly high-contrast colours are perceived separately in the retina ...


8

The human visual processing system receives input from the eyes, and then passes it through a number of areas of the brain that break it down, process it in various different ways, recombine it, and break it down again several times. I'm assuming this question is only about the visual cortex, general theories about how information might be broken down for ...


7

One possibility would be to apply those image filters to a live video stream. Aside from that, you could consider infrared goggles. Not an exact simulation of colorblindness, but it does apparently make red and green into the same color. And if anything, it would let people see the world in differently.



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