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An ongoing conversation on brain and behavior, associated with Biology 202, spring, 1999, at Bryn Mawr College. Student responses to weekly lecture/discussions. A suggested topic was provided, but students were free to write about any other observations, ideas, or questions that particularly interested them.
We've switched from the output to the input side of the nervous system and, in particular to talking about the visual system. In thinking back over our discussions of the blindspot, lateral inhibition, and color vision, what general principles emerge? For sensory processing? For thinking about behavior? Can you think of instances other than those talked about where these principles may apply? What new questions are raised?
I can see how lateral inhibition is very useful in a world such as our own where everything is defined with definite and concrete images. I can also see how non-useful it would be for this system to work the way it does unless one existed in a world with no edges, just differing light intensities. Everything would be constantly changing depending on where we stood or where the light was coming from. Not only would this be very confusing, it would be dangerous and detrimental. In this sense, it is a very good thing that our brain functions in this manner. So should it feel as disturbing as I first thought it was?
Lateral inhibition makes me think of a code. Seeing is just the way the code (consisting of varying light intensities) is translated. It seems to be like reading words on a page. It all has meaning because we are able to take the important information and use it to define something that we can use. Except, unlike most codes that are learned, this one is built into our genetic history. The very fact this exists in our DNA suggests that it is imperative to life and survival on this planet.
So. Sure, this is a little weird, but definitely understandable.
Nice summary, glad its understandable, seems like you talked yourself into being less "uncomfortable" too. Actually, maybe its the lateral inhibition that's the "code", taking the input and transforming it into something "useful"? that "works"? (in our environment). But yes, there are some definite problems with "seeing is believing". Make more sense why we spent so much time last semester on doubt/uncertainty as the basis of science? PG
I am very interested in how dreams are manifested and their relation to the nervous system. It seems that a lot of my dreams are just images, that is, I do not actually hear words in my dream but at the same time I can explain what I have dreamt using language. I tried to look at the latest research on the topic of the manifestation of dreams and I came across what is known as the Sapir-Whorf Hypothesis. Basically, it states that “the functions of one’s mind are determined by the language which one speaks.” Whorf and his colleagues believe that we are able to think only about objects, processes, or conditions that have actual words associated with them. So does this mean that imagination and dreams are limited by language?
One of the experiments that they have performed involved the presentation of a doll who various children see placing a marble in the box. Then the doll leaves the room and the marble is removed from the box and is placed in a new location and then the doll returnes. When children are asked where the doll is likely to look for the marble, they are able to reply that she will look in the box without giving a reason why. The experiment was repeated with deaf children who had deaf parents and these children answered correctly. However, the deaf children with hearing parents often struggled. The Whorf hypothesis predicts this because it implies that the deaf children with hearing parents lack cognitive skills that can only be developed through the use of language (the children with deaf parents can communicate clearly with their parents because of the parents’ proper signing skills).
I am a little skeptical about the way the experiments were carried out because there are many control factors that were not considered (see the web site address below for more information). However if we assume the Sapir-Whorf hypothesis we undermine the implications that the visual system has in our experience of the world. The deaf children saw the act that went on and maybe it was not due to their lack of cognitive skills that they didn’t answer correctly. It might be that because they do not hear language, their visual system processes the outside world in other ways...Perhaps their dreams are just images that do not need explaining in words for their own comprehension.
If you want to learn more about these hypothesis and its implementation go to http://knox.knox.edu:5718/~asoucier/whorf.html
Hmmmmm. LOTS of interesting thoughts in there (and maybe several different paper topics. Sapir-Whorf did indeed suggest "linguistic determination", the idea that what one thinks is constrained by one's language as acquired from culture. It is a live issue among anthropologists (of which Whorf was one), who still collect data exploring it, particularly with reference (surprise) to color names and color perception. There was an interesting recent article of this kind in Nature 318: 203-204 (1999).
While it is likely that language can "influence" (remember this?) how one thinks, there is abundant evidence of other sorts that "thinking" can go on without language and indeed that language may (in part) result from expression of some innate "thinking" patterns. Noam Chomsky, a linguist, was among the first to provide an argument for this, and it has been recently been eloquently talked about by the psychologist/neurobiologist Steven Pinker. There's a relevant Scientific American article in your syllabus (Bickerton, Creole Languages)
I think your skepticism about the interpretations of the observations on children is appropriate. The observations themselves are interesting, though, in relation to two other areas of investigation. One is sign language, and what one can learn about language in general about that (Pinker, among others, talks about this). The other is "theory of mind", the ability to impute intentions/thoughts/an "I-function"? to others.
As for dreams ... We'll take more about those in class. Here's a prelude. PG
My second question was in relation to color vision at night. It is kind of an abstract, philosophical question... We learned that basically the brain can't decipher between different "colored" light at night because the only information that it receives is permeability changes causing action potentials. My wacky question is, if we can't see color at night... how do we know that it's there? I don't think that we could do an experiment to find out, since no humans or similar creatures can "see" night color, and we can't communicate with night "seers" as to if they detect color at night... I know this question seems far off the mark, but I was curious about how we, humans, presume to "know" what we have no tangible proof for.
Interesting question on aftereffects. Not sure I can answer it. My sense is that negative after images (seeing dark spot after bright spot) are better studied/understood. Here are some places to get started if you want to look into it more: http://www.illusionworks.com/html/hall_of_illusions.html and http://www.psy.unsw.edu.au/~brankas/psyc2071/after/afteref.not.html#Lecture Notes.
Your other question I can do better with, and raises a quite significant general point we didn't talk enough about in class. No, we can't see "color" at night. But we can (and have) designed instruments (spectrometers) which can measure the amount of different wavelengths of light. These show that, at night, leaves are reflecting to the eye different amounts of various wavelengths than are tree trunks (amounts which, if more intense, would yield a percept of green for the first and brown for the second). The general point is that the human nervous system clearly has the capacity to transcend (at least some of the inherent limitations of its sensory receptors). The same follows, of course, from the existence of radio and television. We deduced the existence of electromagnetic radiation at frequencies different from those for which we have transducers, and then built instruments to both generate and detect such signals. Pretty clever, no? Now, how is the nervous system organized so it can do THAT? PG
So, what is the reason for our lack of hardware? Obviously, by being able to detect UV light, insects see colorful flowers as landing runways that are practically begging to be pollinated. Humans, with our far from limited sense of vision, seem to be surviving just fine without this knowledge. It is not as though our population is in danger of extinction. My guess is that vision is another characteristic that can be explained by evolution. For some creatures it was evolutionary advantageous to have the ability to detect UV light, while for others, like us, it did not seem necessary for survival.
In closing, one final comment about reality. In examining the visual system, we have seen that the brain "fills in" areas where it fails to receive information, as in the phenomenon of blindspots. If we were to closely examine all the senses, taste, touch, smell, vision and hearing, we would probably find other areas where humans either lack specific receptors or the brain "fills in" for missing information. Imagine just how much information is out there that the nervous system never receives. What a rich world it would be if we could somehow process everything our senses receive directly from the world.
The issue of what differing organisms experience, their different "umwelts", was the subject of an influential book by Jacob von Uexkull which appeared in 1909 and contributed to the origins of ethology, the study of behavior in natural settings and populations. More recently, it has become again important in biosemiotics, the study of signs and meanings in biological systems. So you're in good company wondering how things look to other organisms. While we may never know "exactly" how things look to other organisms, we can get a sense of it from research findings. Here's an example
Yes, presumably what we detect and don't detect has evolutionary explanations. Would the "world" be "richer" if we could detect "everything" about it (how would we know?), or just very confusing? Is it richer now, with recently developed instruments (see my response to Beth above), than it was say five hundred years ago? PG
I was reading about R.E.M. (rapid eye movement) sleep. Recent research has pointed to the possibility that it has a different purpose than what was originally hypothesized. Some believe that the eye movements are simply a biproduct of dreaming--we are moving our eyes just as we would if we were awake; the eye movements are a function of our absorbtion in the dream. Recently it has been proposed that its purpose is to provide a blood supply to a certain part of the eye that will be suffocated if no movement takes place. So, the movements are random and do not correspond to specific unconscious thoughts. I don't have the details of this, but I plan to explore it further.
Its a "sphincter muscle" (you have others) with fibers in a ring and arranged so that when they contract the hole in the center of the ring gets smaller. Yes, the iris does the same thing, but its not the one that controls the lens; that one is the "ciliary" muscle. Yep, contracts for near vision, thus relaxing tension on zonule fibers suspending lens in center of ring, allowing it to relax into more curved shape. Interested in issue of what REM movements achieve. And, if you're looking into it, you might want to know that the muscles of the inner ear also are active during REM sleep. Can provide one explanation covering both phenomena? PG
One case that intrigued me was the study that states that if you are blindfolded and taste a lollipop that you aren't able to guess accurately what flavor it is. In other words, perception of color affects the taste. In the absense of visual information concerning the lollipop, the "blindspot" mechanism kicks in and the brain "fills in" information regarding taste. I read about this phenomenon in "3-2-1 Contact" Magazine when I was a kid (I think) so I'm not sure how scientifically valid it is. (Good magazine, but it didn't cite any sources. I also liked "Ranger Rick.") Have any of you heard of the study. I tried it on myself and I mistook orange for Root Beer, but introspection isn't wholly valid. So, it seems that if this study were accurate that the brain "fills in" data for other senses as well as sight and that the brain's expectations can affect perception.
Yep, another reason not to use "reflex" as a term, at least not as an "explanatory" one. For TWO reasons, as you say. One is that there is not an "automatic" result. The other (related) one is that perception is not "passive", but rather active/constructivist, frequently involving motor processes.
I've been trying to think of a well-studied "lollipop" phenomenon, and am not sure I can come up with one that involves information from different modalities in quite the simple form you describe. I bet they exist though. One interesting question, of course, is how early in the processing sequence such effects occur. Many sensory systems actually have "efferent control" (like the gamma motoneurons and the spindles), making it at least conceivable that some such effects could occur at the transduction step itself. My bet is that most such cross-modality "filling in" occurs later though. PG
Recently I found some information on how stress affects the learning process. It has been proven that when one feels stressed their adrenal glands secrete a peptide called cortisol. High levels of this peptide can lead to the death of brain cells in the hippocampus. Stress can also lead to the lack of one's ability to differentiate what is and is not important. Chronic stress lowers the effectiveness of the body's immune system.
A stressed neuron has fewer and shorter dendrites than that of an unstressed one. The neural structure is changed by a decrease in the serotonin levels due to a reaction of the body and brain from stress. A decrease in such levels can lead to violent behavior. A stressful situation can include environmental factors such as the availability and quality of light. An experiment using students learning in a classroom with either fluorescent of natural light. The study showed that students with natural light miss less school and are reportedly in better moods. Alan Rozanski wrote in the New England Journal of Medicine that an upsetting and threatening environment could set off chemical imbalances. (Eric Jensen, Teaching with the Brain in Mind)
Does this mean that all those who are violent are so because of their environment? If so, does that mean every criminal can be considered "safe" and "cured" by being put in a positive setting? In addition what impact would this have on the legal system?
Interesting article on changing views of mind/body relationships in relation to medicine in the New York Times Week in Review this Sunday (April 18). Yes, indeed, stress can influence nervous system function (and probably structure). Do you have the Jensen book? I'd be interested in seeing it. "... all those who are violent are so because of their environment"? Remember the discussion of three dimensional vision (among other things?). The nervous system does the same thing lots of different ways, and is "influenced" by lots of different things. So, "violence" certainly can be produced in lots of different ways, and correspondingly avoided by lots of different mechanisms. Yes, the developing evidence on brain/behavior certainly has implications for legal procedures. What do you see these as being? PG
The idea that the brain 'makes things up' during our waking hours is very interesting. Although before class discussion it seemed logical to me that this would be happening, it now seems that this occurs much more frequently than I could ever have imagined. Moreover, I was under the impression that humans and other creatures omit or ignore certain visual stimuli more frequently than actually filling in or making up parts of images from the information that is received. In light of investigating dreams for my last web paper, I began to wonder if some of the same structures that are involved in creating images in dreams are also somewhat important in integrating the information received by the eye when awake. For example certain nuclei in the thalamus (located in the brain stem) are extremely important in producing the 'hallucinations' encountered in the dream state. Is it possible that these nuclei are also responsible for the 'filling in' or 'making up' of images produced during waking states? It is certain that waking and dreaming images are very different in that the images produced during the waking states are based on inputs received by the retina, where as those images produced during dreaming states are independent of all external visual inputs. From this, it would seem that even if these areas responsible for dream images are active and functional during waking states, they would be more important in the integration and continuity of images than the full construction and creation of images.
On a related note, what are the implications behind dreaming in color? If it is true that colors are mainly "brain categories", and not "physical categories", are there areas of the brain that are distinctly responsible for recognizing colors? If so, are these areas accessible by other structures in the brain besides the visual pathways (info from the photoreceptors/optic nerve)? It seems that in order to dream in color, other areas, not related to the visual system (since it is not involved in dream imagery), would need to activate these "brain categories" responsible for recognizing colors.
Interesting set of questions. My guess is that the brain stem structures you're talking about either activate or provide input to other structures which actually create the "images" seen while dreaming ... and that the latter are the same ones that create the "images" one sees while awake, so that whatever "filling in" is done is done the same way in both. I'm not sure about this though, and it would be interesting to try and track it down. Yes, there are brain areas particularly concerned with color (we'll talk a bit more about this in class). I'm not sure if it is known whether they are active during dreaming, but there is increasing evidence that many of the same cortical areas active during "normal seeing" are also active during visual imagery. PG
Or at least or brains are not consciously aware of such. I was thinking about the nature of some of the language that we use to describe how we “know” things. For example expression such as “gut feeling” or “I feel it down to my toes,” take on new meaning for me in light of learning that we have as many sensory neurons in our gut as in our spinal cords. And that humans also have a large number of sensory neurons in their feet.
And like the blind person who has damage parts repaired or replaced is it possible to learn to decipher information heretofore unprocessed. If someone showed us how, the way we learn language or music, perhaps from when we were very young might we be able to expand the range of “usual perceptions?”
"Or at least not consciously aware of such" is, I think, the key. I have a little trouble imagining transducers producing signals that our "nervous system" (including the brain) doesn't make use of, but no trouble at all imagining transduced signals which the "I-function" doesn't get (those pheromones come to mind, and there is pretty good evidence that much of the activity of spindle receptors, among other transduced signals, never reaches consciousness. And yes, I can well imagine that we might be able to "expand the range of usual perceptions". Certainly, one can learn to respond to "gut feelings", for example. Maybe "socialization" is a process of learning to "notice" particular transduced signals? PG
I was amazed in class when we concluded that the visual system can only see in detail the sharp edges, and that in between these edges, the brain makes up the rest by examining the surrounding area to decifer what should be in the middle sections, where the edges are not as prominent. My assumption would be that the hearing system should work the same way. But how would it detect the sharp edges, as in the visual system? I perceive that the sharp edges are detected through the difference in pitches. The ear is set up in that when sound hits the tympanic membrane, vibrations are produced through the middle ear and travels to the inner ear, where the nerve endings are located. The sound is detected through by fluctuations in the pitch of the sound. The nerve endings detect different pitches and sends them to the NS. Now, as I perceive it, the nerve endings can depect various sharp pitches and signals to the NS what they are. But, does the brain make up what are between those sharp pitches? I am not sure. I would assume, in between pitches, the brain would make a similar pitches sounds the same, if there are no vast difference in pitch.
Lateral inhibition does indeed play a role in audition, as in most sensory systems. Amost certainly there are several effects, including sharpening of intensity differences and of frequency contrasts. And there is indeed "filling-in" at several levels. One can, for example, leave out parts of words in a speech sequence and the meaning will still be quite comprehensible. Similarly, one can leave out a number of words. PG
Yes, indeed, differences between retinal color blindness and cerebral achromatopsia are interesting. Here's a couple of sites that give at least some useful information: http://www.grand-tours.com/ns/980905/brain.html and http://rosella.bhs.mq.edu.au/~max/Vision/. In addition, Oliver Sacks provides a wonderful extended case study of cerebral achromatopsia in "The case of the Colorblind Painter" in An Anthropologist on Mars(Vintage Books, 1995). An earlier version appeared in the New York Review and is on-line here.
These discussions about what we see versus reality had the same effect. I do not see how there can be a physical reality beyond what we see. Humans make the physical reality, since it is agreed upon what things are. That is all we need to know about what "exists." I could make an equally frustrating argument that scientific experiments designed by humans, as well as tools for measuring what we see, are made with our supposedly imperfect senses and vision, so how accurate can they be? It ends up being a fruitless loop of speculation that does not help us recognize the functioning of the eye. I believe the discussion shoudl be more on what we see, and how we have adapted to the world (which we discussed somewhat) as opposed to a "physical reality" scientists believe exists with their speculations and mechanisms made from their supposedly limited senses that do not see "true reality."
The discussion IS, I think, on "what we see, and how we have adapted to the world". And part of the conclusion, as I see it, is that "true reality" is a concept which perhaps we have "made up" and could do better without? On the other hand, the more we work at the problem, the more we expand our conception of a shared "reality", no? (see my response to Beth above). Which is less "frustrating" and more "progress", no? Anyhow, I agree that we're dealing with some questions many of us had as a child. That's not necessarily bad, is it? And we've got some answers too. There would (as we currently understand it) be electromagnetic radiation without people, but there wouldn't be "yellow". A tree falling in the woods would make air waves, but not "sound"? And so forth? PG
At 18 I was told that most people do not see words when other people talk. That the running ‘closed caption' at the bottom of my visual field is not present for the majority of people in this world. Or that most people do not need to close there eyes when they are trying to spell a word so as to block out the big bold face "bed" "chair" "tv""desk" "pencil" ascribed to any corresponding object in the room. Why you do not see these things and I do I really can not say. It has been officially explained away as a compensatory mechanism, an adaptive feature I developed over my 18 years of confused visual perception, attention difficulties, and short-term memory deficits (ADHD and dyslexia). Almost makes me sound broken I guess -- but it doesn't seem that way -- not exactly. Granted, it is distracting to read 7 lines of text at a time -- not being able to focus on particular visual input-- or for my brain to confuse that which my retina is seeing now and was seeing 5 minutes ago -- not sure wether to put it in short term or long term memory -- but it is interesting and at times intriguing.
So maybe it's not so hard for me -- when Grobstein gesticulates and frets about the front of the classroom challenging all that we have come to know as our collective reality. Perhaps more astounding than the concept that what we believe we are seeing is not real is that perhaps those unrealities which each of us is seeing are in fact different from each other. And if such differences exist are their origins in variations of brain structure or some shadowed involvement of the "I - function". To what extent does the brain shape our perceptions verses our own will to perceive that which we deem present?
It seemed logical to postpone the interpretation of hallucinations, particularly those unrelated to measurable visual stimuli, when addressing the input the eye receives, the image our retina perceives and the interpretation our brain conceives. Yet, with the understanding that a large portion of the "conception" that makes up that which we 'see' is in fact falsified and inserted by the brain, how distant than are those visual hallucinations which we deem markers of psychosis?
I don't want to see things as they really are -- because in fact -- they really aren't. Things really aren't the things that we conceive them to be at all. And thank goodness, or what a logical and constrained reality we would be forced to reside within.
ME? Gesticulating and fretting? Are you SURE? Any of the rest of you see me doing that?
Thanks, Sarah. Maybe we'll let YOU teach the course next time? Yes, there is indeed a fine line between what we "see" and visual hallucinations. Or rather a blur, more of one than most people are comfortable with. Things "as they really are ... really aren't", in a very important sense: that each brain may process the same inputs differently. And that is, by and large, an exciting idea rather than a dismal one, once one gets used to it:
For two thousand years people have believed that the sun and all the stars of heaven rotate around mankind. Pope, cardinals, princes, professors, captains, merchants, fishwives and schoolkids thought they were sitting motionless inside this crystal sphere. But now we are breaking out of it, Andrea, at full speed. ... The old idea was always that the stars were fixed to a crystal vault to stop them falling down. Today we have found the courage to let them soar through space without support ... And the earth is rolling cheerfully around the sun, and the fishwives, merchants, princes, and cardinals, and even the Pope are rolling with it ... The universe has lost its centre overnight, and woken up to find it has countless centres. So that each one can now be seen as the centre, or none at all. .............. Life of Galileo, by Bertold Brecht
At the same time, part of what makes it exciting is that because different people see things differently one can share ideas to see to what extent there are important lessons to be learned from both similarities and differences. And that certainly suggests that the story is not ENTIRELY the brain and its differences: there certainly seem to be SOME things out there which are similarly affecting all our brains. As Einstein put it " The most incomprehensible thing about the universe is that it is comprehensible.". Its worth noting that he also is said to have said "The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka!" ("I found it!") but rather "Hmm....that's funny...". So maybe the best of all possible worlds is to be able to see things simultaneously as they "are" and "aren't"?PG
PS. I started worrying about that second quote, which doesn't actually sound like Einstein, though he certainly did say " If we knew what it was we were doing, it would not be called research, would it?" A different web site attributes the Eureka thought to Issac Asimov. And here's a better site for Einstein quotes, with links to additional Einstein resources.
I was also thinking about an offshoot of the idea that we don’t see all that is actually out there (though in writing that I automatically wonder how we know that, if we don’t pick it up, as I have already questioned…) Anyway, given that we do know this to be true, how does this phenomenon change from one person to the next? Are there cases in which an individual’s lateral inhibition network functions differently, or malfunctions, so that their reality is permanently altered? In The Man Who Mistook His Wife for a Hat, by Oliver Sacks, there is a case where a patient does not see one entire side of anything. The memorable example is that in putting make-up on her face, she only makes up one side of it, because her reality is that only one side of her face is visually there. I read the book a long time ago and I can’t remember the explanation behind this, but it seems likely that it has something to do with the process of interpreting visual stimuli (i.e. light), and the brain’s inability to process through one eye. Could it be that the lateral inhibition network of one eye inhibits too much? Overinhibition?
Another thought I had is about the notion of color, and how we only have pigments for three colors. We see the thousands of colors that we see due to the brain interpreting and categorizing ratios of light wavelengths. In my family, we always had a joke that my father could never differentiate between subtle color differences. When we moved into a new house and were decorating it, he joked that every color was “taupe,” whether it was beige, cream, tan, pale pink, lavender, etc. How is it that he could not see these color differences? How were his brain categorizing the wavelengths differently? And further, since none of these colors actually “exist,” in a way, his reality was more real.
Yep, interesting question is how we could come to know what we don't know (see response to Beth, and whether we can ever know ALL of what we don't know (I don't think so, in principle). Discomfort? See response to Sarah?
We'll talk more in class about people "who don't see one entire side of anything". Its called "hemifield neglect" and is quite interesting, even more so than an "inability to process through one eye, as we'll see. And yes, your father may well have processed wave-lengths differently, but why give him credit for being "more real" as opposed to just "different"? PG
Due to our discussions in the past week, I have been thinking about the reality which we suppose is around us- IS us. The fact that our brain "makes up" information to fill in our blind spots can lead to even bigger questions like: "What ELSE does it make up?", "How can we distinguish between what IS and ISN'T made up", and "To what extent ARE things made up?". Some of those questions can have very unnerving answers.
Color is an aspect of matter that I now must think of as "artificial". Color isn't a property of matter- it's a property of what our nervous systems do with the inputs from the environment we look at. It's hard to imagine, though, what is actually out there.
How does reality differ from the picture in our head in terms of color and even in the actual objects? I am not sure that that question can be answered. It is interesting to try to imagine what the world actually looks like or IS. I don't even know that I can and be confident that I am even close to doing it justice.
Maybe unnerving, maybe exciting?, depending on how you look at it. As we talked about in class, you can check a give picture of "reality" by testing it through other senses, by talking with others, etc. But ... "what the world actually looks like"? Maybe it only "looks like" something if there is someone there to look at it? (see my response to Kim).
This response is to Joe. your idea of a lateral inhibition in the brain to discriminate between pitches as well as sounds of music seems pretty interesting. To add on to your idea I wanted to mention that the temporal lobe is the part of the brain that deals with music. Also, the temporal lobe plays a role in identifying intonation in a person's speech. So taking this into account it seems as though the temporal lobe is the 'lateral inhibition' for sound......
Interesting inference. Betcha, though, that the temporal lobe is only ONE of the places that "deals with music", and hence that there are probably lots of lateral inhibition networks, at different locations, all involved.PG
One of my questions is, however, how does the brain put together all the information from the cones and rods in our retina? There are many aspects of visual processing that need to come together in order for us to see Prof. Grobstein at the front of our class- perception of form, color, movement, depth, etc... When we look at him, we don't simply see a human-shaped thing, a clothing and skin-colored thing, and a gesturing and talking thing... rather, we see the immediate fusion of all these qualities, represented in our brains as our professor. Are there different pathways or different parts of the brain that deal with each individual aspect of visual processing and then fuse all the information into a final perception of the object we are observing? Also, I've heard about something called "motion blindness" where people can see the objects but don't process the movement of that object. Rather, from one moment to the next, the object simply seems to appear in a different place than it was before. What is going on here? Are only certain parts of the retina picking up light reflecting from this object, or is this a problem within the more central processing of the nervous system??
If you don't mind further rambling speculations, I've also been thinking about not only the images we "see" from our brain's interpretation of the world outside, but also about the images within our brain, generated not by light reception on the retina, but rather from memories. When we close our eyes and picture, say, having lunch earlier today, we have a precise, colored image in our heads. Yes, I may be getting ahead of myself, but I think this idea may also correlate somehow with other people's comments regarding dreams. The images in our head from dreams are not based on external imput/ light reflection on the retina, but rather are generated by our brains. The images in our heads which correspond with certain memories are also not based on external input, but rather activity within the brain. What, then, is the difference between images from memory and images from dreams, which are then inprinted into memory? is there a difference at all?
You're doing a good job of asking the questions that take us to the next steps. Thanks. And, obviously?, I don't mind a certain amount of rambling, and hope you don't. Anyhow, we'll talk shortly about the issue of where all the various aspects of vision get put together (including some discussion of "motion blindness"). And about various forms of images, and whether there are or are not differences. PG
After a week or two of being aware that my entire world was an image created by my nervous system, I am getting used to the idea. I actually have had a sense that what we perceive as reality could actually be a construction of our nervous system for a while, because dreams seem real to me, but I know that they are not. Yet, while I am dreaming, my dream world is as real for me as my waking world. I wonder if what we perceive as real is really more important than what is actually real. Perhaps most of my world is just a illusion, but as long as I believe in it and it functions for me, it does not really matter whether or not it is a figment of my imagination.
"Does it really matter if we can still function"? Depends a bit, I guess, on how curious one is. And, of course, on how good a particular "figment of my imagination" is at keeping one alive, safe, happy, and so forth. The two, I suspect, go together, in the sense that being curious makes one more inclined to test one's figments to see whether there are better ones, and that, in turn, gives some assurance that, in a changing world, one has, in advance, alternate ways of seeing that might prove useful to staying alive, safe, happy and so forth? Glad you're getting used to the idea. Is sort of fun, no? And maybe useful too? PG
Last week I learned that a "wall is a wall is a wall" because of the brain’s remarkable ability to extract constancy out of variable physical reality. Because my 2nd web paper deals with the subject of creativity, I am struck by the brain’s determination to create constancy out of a world that can so easily be perceived in so many different ways! The brain is so good at creating order! It seems almost impossible to somehow defy the brain’s drive toward it’s established way of looking at things!
When we look at a wall, our brains create a "wall" for us by disregarding a lot of confusing sensory signals and by "making up" a lot of our perception of things we are receiving no sensory information about. Thus, despite lighting conditions or weather conditions, or the condition of a particular wall (dirty, clean, painted or covered with wallpaper, etc) we are aware of an "essence of wallness" that allows us to see the wall. I am guessing our perceptions of things like music (or of "god" or of any "given under-represented group," etc) must be as constant as our perception of "wall". We understand music in terms of certain modulations and harmonies. Our brain’s definition of the "essence of music-ness" leads us to recognize many different things as music. It also limits us – preventing us from experiencing certain things as music. This must be extremely difficult to break out of, given the brain’s powers as a sort of "master of illusion!"
While researching my web paper, I read an interesting article by Margaret Boden describing creativity as the "transformation of conceptual spaces." In my own brain, I see Boden’s conceptual spaces as rooms defined by those "essences of wallness! Boden describes a conceptual space as a style of thinking. Its dimensions are the organizing principles that unify and give structure to the relevant domain. This functions as a generative system defining a range of possibilities. Boden describes the history of western music as exploration of the conceptual space generating tonal harmony. As musicians experimented more and more extensively, eventually the space was transformed when someone (who happened to be Schoenburg) dropped one of the central constraints of tonal harmony (the "home-key") and created the space of "atonal" music. How did Schoenburg escape the brain’s drive toward the constancy of the walls limiting the conceptual space? In a flash, the wall was not a wall, and was seen as nothing but a variable pattern of shifting light. That moment seems to be the moment to redefine the wall. By "choice?"
NICE question (and nice summary of where it comes from). Yes, THAT is yet to be accounted for. How DOES one get through the wall, or break out of the crystal sphere (see reply to Sarah above). We'll take a crack (sorry) at that over the next week. Is it enough to "choose" to do it? Or is something more needed? PG
The problem of “true reality” then becomes a philosophical question which is interesting to ponder, but does not change our day to day functioning (other than to make us aware of these issues, and be more skeptical of what we are presented with.) For me, it is very interesting to be taking this course at the same time as an intro philosophy course. Texts we have read by Descartes, Hume and Kant all deal with this issue of “reality”, that our perceptions are distinct from the things they perceive. We can never truly know external objects as they really are; we can only know them through our senses and through our mental conceptions of them. This also relates to consciousness, the active awareness of our perceptions. I have always thought that human conscioussness is a phenomenon which will never be explained by biology. If I am going to hold onto my concept of a soul, conscioussness seems to be a necessary element which is innate, but not biological. But my web paper dealt with the biology of consciousness, and I am beginning to see how we can study conscioussness (at least through those who lack it) with a neural component. Again it is fascinating for me to see philosophical theories examined on a neurobiological level.
I guess these questions are worth asking when someone’s reality detrimentally differs from the commonly accepted one. Lacey Tucker touched on this with Oliver Sach’s book, and I would like to know more about how our normal processing of perceptions may be changed so that reality is altered. This discussion definitely helps give a framework in understanding certain forms of mental illness.
Seems to me you end up (appropriately) in a place a little different from the one you started in ("it seems to me that these occurrences would be minor, curiousities at best"=). As you go on to, there are actually some pretty big and significant-in-daily-life issues which are affected by a recognition that "what we see in our minds is not the same as external reality". Maybe its not entirely true that "the reality with which we are presented is the one best serves our functioning as humans in our environment (boldface mine)"? Maybe the environment isn't constant? Maybe we can make make presented realities which are better? Maybe changing presented realities itself somewhat changes the "environment"? Current "presented reality" has the earth moving around the sun, even though it doesn't really look that way, and light travelling in all directions from a point source, even though ... Which does have "day to day" effects, no? I'm glad the course fits with your intro philosophy course. Maybe philosophical questions are something more than just "interesting to ponder"? PG
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