Regarding Perception, Photography, and Painting…PART II

(CONTINUED FROM PART I)

While we are on this color issue, exploring the counterintuitiveness of our vision system, and examining the comparison between a camera and the eye, I’d like to take a moment to share an interesting argument that I encountered not too long ago from, believe it or not, a professional artist who was absolutely convinced that color is indeed part of the environment. (I explore this idea in the above mentioned 2017 article.) No matter what evidence I was able to put forward to demonstrate that this was NOT the case, he would not budge from his position. When I asked him to present the evidence that justified his position, he stated that color MUST be a physical property of the environment “ because a camera can record it.

Now I am sure that a good number of you reading this have already realized the glaring fatal flaw in this argument, but for many individuals unfamiliar with the fundamentals of color vision and color photography, the argument definitely seems to have some teeth. However, like most intuitive arguments for a flat-earth, young earth, or intelligent design, such arguments quickly deteriorate with an increase in scientific literacy and critical thinking. Just to be clear though–with color photography, electronic sensors or light-sensitive chemicals respond to specific aspects of electromagnetic radiation at the time of exposure. The recorded information is then used to create a percept surrogate by mixing various proportions of specific light wavelengths (“additive color”, used for video displays, digital projectors and some historical photographic processes), or by using dyes or pigments to remove various proportions of the particular wavelengths in white light (“subtractive color”, used for prints on paper and transparencies on film). The color you are perceiving in a surrogate, like a traditional photograph or digital image, is being generated by the wavelengths of light emitting from the surrogate-not because the camera “captured” color like some fairy in the garden.

What might wrapping our head around this even easier is if we take a moment to clearly define two basic terms concerning the manner with which we interact with the environment, sensation and perception. These terms are often used synonymously–but they indeed describe two different aspects of what we normally understand as “sensory experiences.” Sensation describes a low-level process during which particular receptor cells respond to particular stimuli. At the level of sensation, our sensory organs are engaging in what is known as transduction (or in our case, as we mentioned earlier, phototransduction), or the conversion of energy from the environment into a form of energy that our nervous system can use

Perception , on the other hand, can be simply defined as the assignment of “meaning” to a sensation.

So what is actually happening when we visually encounter something that we might understand or describe as “blue”?

Putting aside scenarios in which the object may be an actual source of light, or a structural configuration that is bending light, it is likely that the surface of the object is absorbing all of the available wavelengths of the visible spectrum except for some that are relatively short. Now the standard human observer has a specific type of photoreceptor cell in the retina that is “tuned” for such short wavelengths. That means that when this particular cell type encounters this type of wavelength, it responds by initiating a complex cascade of electrochemical events that will eventually lead to more and more complex processes along a particular “route” we are currently exploring–the “visual pathway”. This low-level cascade initiation is what we could define as a sensation .

The cascade of events initiated in the retina will eventually lead to specific activity in other, “higher”, or more complex processing regions of the brain such as, but not limited to, the lateral geniculate nucleus of the thalamus, the striate and extrastriate cortex of the occipital lobe, and the temporal lobe (regions which we will be heading to soon in our visual pathway when our walkthrough continues). It is through the aggregate activity of these brain regions that we find a perceptual response–in our case here–”blue.”

So as you might already be starting to suspect, in this example, the object in the environment is NOT physically blue, the wavelengths reflected off the surface of the object are not physically blue, nor do the photosensitive cells referenced here “sense” blue. Blue is not a sensation–rather, it is a perception . We assign “blue” to a particular sensation that is a biological response to a certain wavelength.

Hopefully that makes some sense, clears up a few more counterintuitive factors, and allows us to continue our glimpse at a few key points on the visual pathway.

From the retina we will jump to what is often referred to as the main relay station of the brain known as the thalamus, or more specifically, a region of the thalamus called the lateral geniculate nucleus, or LGN. Information from both motor and sensory systems (with the exception of the olfactory system) relay signals through the thalamus where they are processed before being sent off to a myriad of cortical regions. Yet, the LGN does seem to be much more than a mere relay station or gateway to the visual cortex. It is a multi-layered array of sophisticated microcircuits that would seem to suggest a region of very complex processing. What makes this area even more fascinating is that only 10% of the inputs to this region are coming from the retinas. The other 90% are inputs from a number of cortical and subcortical regions including significant input from the primary visual cortex itself. With what we can observe anatomically, it would seem that this region might be a major site of top-down influence. In other words, it appears that the visual cortex may play a very large role here in controlling what is actually sent on to… the visual cortex. (Hopefully, at this point, many of you are starting to better appreciate just how unlike a camera this system really is.)

From here we will exit the LGN via a large fan of axons radiating outward, appropriately dubbed optic radiations, and land on the banks of (and somewhat within) the calcarine sulcus (or fissure) of the occipital lobe. The noticeably striated region of tissue is home to what is called the primary visual cortex. Here we find the most studied part of the visual brain.

The part of the occipital lobe that receives the projections from the LGN is known as the primary visual cortex (also referred to as visual area 1 (V1), as well as the striate cortex.) Immediately surrounding this region, above and below the calcarine sulcus are what we dubbed extrastriate regions. These regions consist of visual areas 2 (V2), 3 (V3), 4 (V4), 5 (V5 or MT) and 6 (V6 or DM). Now before you shudder expecting me to go into a large series of complex processes here–don’t worry. I am not. What I am going to do is jump forward to the cascades of neural activity that unfold from here furthering our understanding of this elaborate “pathway.”

So where do things go from here? Each V1 (remember that we have two halves to the entire lobe here) transmits information to two distinct pathways or processing “streams”, called the ventral stream or “what” stream, and the dorsal or “where” stream. The information that is relevant to these two pathways is separate but remains physically integrated through much of the visual pathway. It is when this integrated information reaches “higher” levels that we see physical separation.

Anatomically, the ventral stream begins with V1, goes through V2, through V4, and then on to regions in the inferior temporal cortex (IT). This stream is often referred to as the “what” pathway as it is associated with form recognition and object representation. As such we find neurons in this stream that respond selectively to signals that might represent particular wavelengths of light, shapes, textures, and at the “highest” levels of this pathway, faces and entire objects. There are a number of regions within the inferior temporal cortex (ITC) that work together for processing and recognizing neural activity relevant to “what” something is. In fact, discrete categories of objects are even associated with different regions. For example, the fusiform gyrus or fusiform face area (FFA) exhibits selectivity for incoming activity patterns linked to faces and bodies while activity in the parahippocampal place area (PPA) helps us to differentiate between scenes and objects. The extrastriate body area (EBA) aids in distinguishing body parts from other objects while the lateral occipital complex (LOC) assists in discrimination tasks regarding the separation of shapes and “scrambled” stimuli. These areas all work together, along with the hippocampus, a dynamic memory region that is believed to be significantly involved in object “compare and contrast” tasks, in order to create an array of understanding of the physical world. This pathway also holds strong connections to the medial temporal lobe ( long-term memories), the limbic system (emotion), and the aforementioned dorsal stream. This stream has a lower contrast sensitivity compared to the dorsal and is somewhat slower to respond. However, it does have a slightly higher acuity than its counterpart and carries all information about what will eventually yield an experience of color.

The dorsal stream also begins with V1 and goes through V2, but then travels into the dorsomedial area (V6/DM), middle temporal region (V5 (MT)), and onto the posterior parietal cortex. The dorsal stream, often referred to as the “where” or “how” pathway is associated with motion and location. As such, within this stream one would find neurons that show selectivity, not for signals representing shape or light wavelength, but rather for signals that represent location, direction and speed. This stream is essentially “colorblind”, but has greater sensitivity to contrast, is quicker to respond (albeit more transient), and has a slightly lower acuity.

Illustration of the ventral processing stream, of “what” pathway, and the dorsal processing stream, or “where” pathway.

So, like with our blindspot, blood vessels, and the spatial imprecision of our periphery, can we see some demonstration of how these two streams process things differently?

You betcha.

One of my favorite examples for this is to introduce a stimulus that sort of pushes the two streams out of balance. If we could make an object or image visible to only ONE of the streams then we might experience something quite interesting. And indeed we can–with color.

Remember that we stated above that the “where” stream is essentially colorblind. As such, we can present a stimulus that contains two or more colors that are perceived as reasonably equiluminant (appears to be of the same level of lightness or brightness.) Here is one such example:

Do you notice an odd visual shimmer, jitter, or vibration when trying to read the letters here? This is because while your “what” system can easily process the color contrast, the colorblind “where” system cannot. In other words, your “where” system is having a heck of a time trying to determine where the boundaries of those letters actually are.

One of the most famous examples of an artist exploiting this issue is Claude Monet’s Impression Sunrise. In the piece, many reported that the sun within the image appeared to “vibrate.”

Impression, Sunrise by Claude Monet 48 cm × 63 cm (18.9 in × 24.8 in), Oil on canvas, 1872

Grayscale version of Impression, Sunrise by Claude Monet. Notice how the sun is nearly invisible due to its equiluminance with the surrounding clouds.

Neurobiologist Margaret Livingstone explains the peculiarity of Monet’s equiluminant sun in her book Vision and Art: The Biology of Seeing . She writes, “T he sun in this painting seems both hot and cold, light and dark. It appears so brilliant that it seems to pulsate. But the sun is actually no lighter than the background clouds, as we can see in the grayscale version. It is precisely equiluminant with–that is, it has the same lightness as–the gray of the background clouds. This lack of luminance contrast may explain the sun’s eerie quality: to the more primitive subdivision of the visual system (which is concerned with movement and position) the painting appears as it does in the grayscale version; the sun almost invisible. But the primate-specific part of the visual system sees it clearly. The inconsistency in perception of the sun in the different part of the visual system gives it this weird quality. The fact that the sun is invisible to the part of the visual system that carries information about position and movement means that its position and motionlessness are poorly defined, so it may seem to vibrate or pulsate. Monet’s sun really is both light and dark, hot and cold.”

Equiluminance (left) can indeed be a powerful device for achieving a sensation of vibration or pulsation–however, specific variations in contrast, color and element orientation can give rise to even more powerful perceptions of motion such as those created by psychologist Akiyoshi Kitaoka to demonstrate the effect of “Perceptual Drift” (right).

And while you can find countless visual demonstrations in textbooks, classrooms, and websites (often labeled as illusions) demonstrating that what we see does not accord with an objective reality–I couldn’t pass up an opportunity to share one of my favorite, canonical examples for experiencing it–the simultaneous brightness/lightness contrast demonstration.

Demonstration of simultaneous lightness/brightness contrast. A target (grey square) with a lighter surround (left) is perceived as being darker than an identical target with a lighter/brighter surround (right). If our visual system operated via objective samplings, one might suspect that there would be no such perceived disparity here.

So at this point–with this limited glimpse at the mountain of interdisciplinary evidence available to us–I hope that you can better evaluate the claims that visual perception can be objective. And if that claim is false–so are those built upon it . I am hopeful that you, the reader, may consider using this paper as a reference when needed to better grasp some features of the visual pathway as well as some basic ideas about the nature of visual perception.

Before closing, I would like to briefly address two additional issues that are connected to the topics discussed here thus far. One is the idea that learning observational representationalism is in fact, “learning to see.” You will remember that our aforementioned artist and author, Virgil Elliot, continues to promote this idea. Unfortunately (or fortunately depending on how you might like to consider the idea), this is indeed not the case. While your perceptions can indeed be molded by experience and assumption, the practice of observational representationalism will not fundamentally change the nature of your vision system. What the practice CAN do is cultivate the relationships between specific visuomotor responses and specific types of visual information that are conducive to representational efforts. The second is an intuitive argument that was put forward in the online thread I started that I did not address adequately. I felt that the answer really needed to be in the context of the more robust explanations and insights that I hope I have provided here. The argument was that photograph (a percept surrogate) should be considered a “less objective” reference source due to the fact that a surrogate is one step removed from the actual subject (the live percept.) And while this may initially sound like a solid argument, it contains a fatal intuitive error. You see, the idea of objectivity in this context is describing the nature of the perceiving entity–not the subject of the perception. This is almost like arguing that the closer you are to a live piano being played, the more objectively you will perceive the sound. In actuality, you will respond to any perceptible, appropriate pressure waves in the manner that you and your species have cultivated. No perceived sound originating from a piano, whether you are 10 feet away from a Steinway or listening to a CD of your favorite ivory-key hits, will be more or less “accurately” objective. I hope that is clear enough now.

Again, as I stated in the 2015 article I mentioned, There are definitely problems to contend with when utilizing photography in the pursuit of representational painting or drawing. However, the points that are often put forward to argue against the use of photography in representational painting communicate more of a general misunderstanding of visual perception than anything else. Now I agree that there are some truly GREAT reasons not to use photography in specific painting and drawing scenarios. However, you must be aware of the goal or intention of the artist before you can effectively determine the advantage of any reference source. Yes, some photographic processes may have specific limitations—but those limitations may not exceed the advantages in all cases, across all contexts. .

I hope that you have found this paper to be informative. I know some parts of it are very dry–but I wanted to offer a more robust resource than what I have been able to provide in a flurry of comment fields on social media. Please let me know if you find any factual errors in what has been provided here. I would also like to invite anyone that was referenced in this paper to feel free to submit any corrections, clarifications and/or refutations for inclusion here.

Best wishes all!

WRITTEN BY

Anthony Waichulis

Anthony Waichulis

is a contemporary Trompe L’oeil painter whose works have been published in major art publications including The Artist’s Magazine, Fine Art Connoisseur, American Artist, American Art Review, American Art Collector, Art News, as well as many others.

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Wow, thanks for this. I loved the article though I would be lying if I said I understood a lot of it :grin:. Definitely need to remember to reread it again soon though.

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I have to confess to finding Vision Science very difficult. This is the sort of article that 4 years ago I would have found very demanding. However having studied vision science these past four years, and read both the works you recommended to me, I have really come to understand the points you are making fairly well.

The way I understand it is: if we imagine someone looking at a subject, then light comes from the subject and hits their eye. When it does, it then initiates a sequence of electro-magnetic impulses that surge through the brain and body of the person.

The job of the artist therefore is to trigger those exact same electro-magnetic impulses.

Thing is however, is that these electro-magnetic impulses that are triggered will vary from one person to another. Let’s suppose an artist does a portrait of a boy. Now, when the boy’s mother sees him, there are going to be an awful lot of electro-magnetic impulses that will surge through the mother and these will be very deep rooted. For example all sorts of memories, emotions and instincts will be triggered.

On the other hand, if a random man, who only knows the boy very vaguely, sees the boy, it sets off a (mainly) entirely different set of impulses, which are probably not so numerous and not very deep rooted.

However what you have to understand about the fact that the mother and the random man react differently to the same stimulus, is that this phenomena doesn’t just start at the eye. I mean it is not the case that the same light patterns hit both the mother’s eyes and the random man’s eyes. That is not true. Rather each eye is already biased toward looking for what it ‘wants to see’.

To explain this further, remember that we can put an object directly in front of person 1, then replace person 1 with person 2, so that they are in the same position and their heads and eyes are facing the same way. That still does not mean that they are looking at the same thing because each person will move their eye, and squint to a different degree, and so on, according to their own biases. You cannot force two people to take the same patterns of light upon their eyes.

For example, suppose the boy has a big birthmark on his face. The mother’s eye however, has become trained over time to virtually not see it. Whilst the random man’s eye will be on factory settings default, that will specifically hunt out such a birthmark. Obviously, if the artist makes a big thing of the birthmark, the mother might find the artwork both unrealistic and bad, whereas the random man might think it very accurate.

Anyway, in general, what this all means is that the artist is up s**t creek so to speak! Because he cannot guess how the mother sees her child, nor either the random man. I mean there is probably more chance that the artist sees the boy in the same way as the random man, but if, for example, the random man was bullied at school by a boy who looks like the one in the painting, then all bets are off.

Thus an artist should be able to somehow know what the eye of the beholder is ‘looking for’ (an impossible task) whilst at the same time being aware that it’s a waste of time anyway since all beholder’s have eyes that are looking for something different!

And even if the artist somehow manages to overcome these two obstacles, if the surrogate deviates ever so slightly, it might fail to initiate the full cascade of electro-magnetic impulses that surge through the body of the viewer, when normally they see the boy.

A further problem arises in setting off unwanted electro-magnetic impulses. For example, let’s suppose the artist draws the boy well but puts on an artificial blue background. Now, the mother of the boy let’s say, when she was young, was abused by a man who always wore blue. She is deeply psychologically scarred and blue triggers her, but the birth of her son and his childhood belongs to a totally different era of her life which she doesn’t ever connect to her abusive childhood.

Anyway, by arbitrarily painting the background of the work blue, the artist has now triggered a series of electro-magnetic impulses in the mother, which are not only traumatizing to her, but they are not ever triggered simultaneously as those triggered by the sight of her boy. This will confuse her, and make the painting of the boy both less realistic and not as beautiful as it would have been without the blue background.

Anyway, I’m interested to know, did you always have an appreciation that vision science was important to art? It is not something I have ever seen any other artist talk of, at least not at a scientific level. Most artists never seem to consider such subjects, and I too never would have, had it not been that you always raised the issue in your writings.

Having said that, it does seem like all the painters of the classical era were very scientific in their thinking so perhaps this – the separation of science and art – is just a 21st century problem.

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This is only true to a degree. It is true that we can find great variety in connectomes (relating to specific wiring states/changes via global gene expression patterns in the nervous system during the course of the life cycle.) —it is important to remember that we share the same basic genome scaffolding (23 chromosome pairs with a total of about 3 billion DNA base pairs.) This sharing means that our biology will be similar enough at a certain level of granularity so that reasonably successful predictions about how a representation may be experienced.

Yes, in some contexts this could describe certain goals of an artist–however, just to clarify–in this case you are working to elicit activity in the viewer that is similar to activity in that viewer in the past. Therefore, the artist and the viewer need not share the same small-scale, local network “wiring”.

Here, we need to be careful about what is being communicated. Yes, eyes can be physically different on many, many levels—but I think that you mean here is that the brain (where perception occurs) is primed to see something “different” due to an array of bias. This latter–sure. However, the former–limiting ourselves to the general scaffolding of the mechanics of phototransduction–can be said to be relatively the same (again, at a certain level of granularity–otherwise we might need a separate textbook to describe what is happening at the level of phototransduction for every possible individual.)

This is where we can easily slip into one of Xeno’s paradoxes. (e.g., if the space between an arrow fired from a bow and its target can be divided infinitely—then the arrow should never arrive at its mark as it would first have to travel across infinity.) A similar problem can start to unfold here—if every person might perceive things differently then we can never know how someone might perceive something. Like the paradox, this latter comparison strays off path quite a bit. First, remember how I stated previously that I subscribe to the empirical ranking theory of perception (vision works by having patterns of light on the retina trigger reflex patterns of neural activity that have been shaped entirely by the past consequences of visually guided behavior over EVOLUTIONARY and individual life time.) Therefore, we share enough across the species to make relatively effective predictions about how another may perceive a stimulus (again, at a certain level of granularity.) This level of granularity is vast enough for representational artwork to be successful. I mean, people are not writing about my latest painting of a baseball glove stating “Hey, Nice camel” or “Wow, what a cool stack of pancakes!” Second, building on the first point, remember in my writings of Yarbus’ work. He states that “…In conclusion, I must stress once again that the distribution of the points of fixation on an object, the order in which the observer’s attention moves from one point of fixation to another, the duration of fixations, the distinctive cyclic pattern of examination, and so on are determined by the nature of the object and the problem facing the observer at the moment of perception.” -Yarbus, A. (1967). Eye movements and vision (B. Haigh & L. A. Riggs, Trans.). New York: Plenum Press, So while we cannot determine a viewer’s exact pattern of saccades and fixations, we will find such variation within a finite range of possibilities. For example, I don’t you would find your above scenario unfold in which the man shown the child, states, “Oh my goodness, I didn’t even see the child!”

Sometimes “possible” scenarios are put forward to highlight a potential problem or concern with considering how this might manifest outside of the hypothetical world. For example—since blue is so common in our world, is she often confused over whether or not the boy she is seeing in real life does in fact exist due to blue also being experienced in the visual field? LOL! Sure—some crazy things might happen—but I don’t think that we will ever be able to be aware of every conceivable variable to the point were painting is seen as a exercise in mastered determinism (but it doesn’t stop us from trying anyway!)

My traveling down this road of scientific inquiry began after art school when I wanted to find better strategies for effective Trompe L’oeil. I mean, I realized that the illusion of reality that I wanted in my representational painting could not be just a matter of how well you can render. Therefore, I began to study more and more about the psychology associated with of visual perception—which then led to vision science, evolutionary theory and evolutionary psychology, and more recent arenas like neuroaesthetics. It’s a rabbit hole I decided I would never leave. LOL!

Thank you for your efforts to continue these conversations Thomas. I know that some of these topics can seem dense (they still seem that way to me at times!) It is always greatly appreciated. BTW–I hope that this finds you safe and well and with a new masterpiece on the easel before you!

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Thanks for the response Anthony.

  1. Yes, just to be clear, I was not suggesting that two different people experience something radically different when they look at an object. Simply that such subtle differences do exist. And whilst they probably mean very, very little in terms of every day objects, perhaps they do play a role in portrait painting. Because a mother might be heavily invested in her child, more so than an artistic stranger, this might explain why often people are disappointed with portraits of their loved ones.

  2. In terms of my example of a mother having a trauma that is triggered by the colour blue: clearly here the colour blue – which I chose just to keep things simple – is rather stupid, in that the colour blue is ubiquitous. Perhaps I should have said something like: suppose the mother was abused by someone who listened to Elvis. And that the artist arbitrarily painted a copy of an Elvis record in the background of the painting.

Again, to be clear, the point I was making was not that these things often happen, or even sometimes happen, but that if you take our understanding of vision to the limit they could be possible.

  1. Yes, you are correct I meant to say that that the brain is primed to see something different due to bias. Rather than what I stated which was that the eye is biased.

  2. I hope your well too. And yes I have done some pieces lately that I have been very proud of, though I wouldn’t quite call them masterpieces!

Actually, I’ve also been doing some research on evolution. Are you aware that Neo-Darwinism is probably on its last knees and is about to fall? I’m sure you might have heard about something like epigenetics. The thing is, is that the vision science that you propound seems very much in line with this more holistic epigenetic approach. For example this comment:

‘vision works by having patterns of light on the retina trigger reflex patterns of neural activity that have been shaped entirely by the past consequences of visually guided behavior over EVOLUTIONARY and individual life time’

is very much in keeping with the epigenetics philosophy. That said, it will be interesting to see how new theories of evolution might impact our thinking of both biology and psychology, and whether or not certain Neo-Darwinian implications will still hold true (though I think in a lot of cases they will).

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