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14

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 ...


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 ...


13

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

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

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

There is no true frame rate of the eyes, but there are limitations. The brain uses blurring to simulate continuity. Films are shot at 24 frames per second; if you go too much lower than that, the film will seem choppy. This is because the motion blurring process is too fast and it finishes "blurring" before the frame changes, so you just see choppy frames....


9

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 (...


9

Bach-y-Rita's Tactile Vision Substitution System (TVSS) project was initiated in 1963 and he has since been regarded as the founding father of sensory substitution. The concept of sensory substitution refers to the process of obtaining information about the world from a functional sensory system (e.g. touch) that would normally be obtained from a lost ...


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

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

Seems this is a newly discovered phenomenon! Tangen, Murphy, and Thompson (2011) describe this as a result of their method of presentation: alignment of the pupils and fast cycling through faces with different proportions. It is also important that the cycle of new images remain uninterrupted. They say "relative encoding seems to drive the effect," and list ...


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

It appears that throughout your question you are touching on multiple questions and topics. I will address them in a series of quotes and responses, beginning with the title: Are colors real? They are not physical things. Colors are a form of perception (an abstraction). They exist in your head. In physics the perception of colors is caused by light ...


7

Actually, black objects absorb light across visible frequencies indiscriminately, but not completely. So some light still reflects off them. This is described on this Q&A of the Department of Physics, University of Illinois at Urbana-Champaign. But even if there was a perfectly black objects which absorbs 100% of the light that falls on it, you could ...


7

The bouba/kiki effect is the phenomenon that about 95% of subjects assign the name bouba to a blobby form, and the name kiki to a pointy shape (Fig. 1). Fig. 1. Kiki and bouba, at least in 95% of the people. source: Synesthesia Test It is thought that the reason behind the strong preference is that the sharp changes in visual direction of the lines in the ...


7

Short Answer It appears that stimulation of the thalamus would invoke feeling of pain: Direct deep brain stimulation (DBS) in the VP thalamus from patients without pain typically evoked nonpainful, paraesthetic sensation. DBS at the core and posterior inferior region of the VP thalamus can evoke pain sensation without specific topographic distribution. ...


7

There is a lot going on in your question. QUEST, as well as many other adaptive procedures, is well suited for a task like estimating morph distance in a 2-AFC paradigm. There are, however, a couple of points in your question, that make me think QUEST is not a good paradigm. The QUEST paradigm is designed around setting the signal level to find the the "...


7

Some of those pop science articles might be simplifying a bit by saying the stimuli are provided to the left or right eyes. In fact, they are actually presented to the left or right visual field which is an important distinction. The left visual field, from both eyes, goes to the right hemisphere, and vice versa. The experimental paradigm is illustrated in ...


6

From personal observation, the consensus seems to be that the two streams hypothesis is an oversimplification of the truth, albeit a useful one. The primary reason that this hypothesis is seen as an oversimplification is because there is a lot of cross-talk between the two streams. For example, Zanon et al. (2010) provides evidence for functional ...


6

It has been theorized that it has to do with "visualizing" dreams, but the movements themselves are by virtue of the pattern of electrical activity as the waves travel between the Pons (in the brainstem), Geniculate nuclei (in the thalamus), and Occipital lobe. From PGO Waves PGO waves and REM sleep PGO waves are an integral part of rapid eye ...


6

From Stevens & Galanter (1957) Although an extensive investigation of the subjective scale of brightness is still in progress in this laboratory, enough has been learned to show that, for patches of white light viewed in a dark room, subjective brightness is a power function of luminance. Moreover, the exponent is of the order of one-third ...


6

Interesting question! I performed a fairly extensive search in Google Scholar and Scopus using various keyword searches, including, but not limited to "color blindness and plasticity", "color blind and brain", "dichromates brain", and "monochromates brain". Strikingly, I found nothing. The reason is aptly explained by Solomon & Rosa, 2014 and I quote ...


6

Visual acuity is highest in the foveal region, namely around 1/60 of a degree, or 1 minute of arc (1 MAR). At about 30 degrees of eccentricity, visual acuity is reduced to anywhere between 1.5 and 10 MAR when determined by a shape recognition task, as shown in Fig. 1 taken from Lie, 1980: A later study (Anderson et al., 1991) shows the following picture: ...


6

Short answer The retinal image corresponds more to a bitmap, than a vector-based image Background The retina contains a layer of about 100 million photoreceptors that are topographically organized. In other words, each photoreceptor codes one specific pixel in the field of view. In turn, the nerve fibers running from the eye to the brain are also ...


6

In general, evidence suggests that we are attracted to contrast rather than brightness (luminance). For example, the onset of a bright light on a dark background is often used as an exogenous cue for visual attention, but a dark cue on a bright background works just as well. So, signs generally aim to be high contrast against their background. Contrast shows ...


6

The short answer is that it is not necessarily easier to read black on white. Contrast is more important in lightness and colour, it just so happens that black and white is the highest contrast. So its no accident that most books are in black and white. There is a plethora of research on perceptual processing which is easily found on google scholar if you ...


6

Objects are visually perceived when they reflect light. A black object does not reflect any light. In other words, no photons are reflected to be detected by the photoreceptors in the retina. A black shape on a colored background appears black because its brightness approaches zero relative to its surroundings. Black, as any other perceived hue, is a ...


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