Biology 202
Neurobiology and Behavior
Spring 2001

Forum Archive - Week 9-10

Lateral inhibition, the brightness/color distinction, and color processing itself all lead to some important conclusions about "perception" (the "picture in your head") and about how it is achieved by the nervous system. Among them is a possible answer to the old question "if a tree falls in a forest and no one is around, does it make a sound?". The answer, it was suggested in class, is "no". What do you think of the logic (observations and interpretations) used to reach this answer? about its implications?


Name: Paul Grobstein
Username: pgrobste@brynmawr.edu
Subject: week 9
Date: Sat Mar 31 10:08:30 EST 2001
Comments:
So ... we're still talking about the input side of the nervous system. As always, whatever thoughts have been on your mind/brain are welcome here. To get you started (if you need something):

Lateral inhibition, the brightness/color distinction, and color processing itself all lead to some important conclusions about "perception" (the "picture in your head") and about how it is achieved by the nervous system. Among them is a possible answer to the old question "if a tree falls in a forest and no one is around, does it make a sound?". The answer, it was suggested in class, is "no". What do you think of the logic (observations and interpretations) used to reach this answer? about its implications?


Name: Daniel
Username: dburdick@brynmawr.edu
Subject: Flight Simulator
Date: Sun Apr 1 14:23:06 EDT 2001
Comments:
I was reading yesterday an article by Patricia Smith Churchland in which she presents a highly logical defense of the reductionist approach to explaining consciousness, the approach that argues that consciousness and behavior can be fully explained by neural activity (brain=behavior). In the article, she mentions an objection to this approach raised by D.C. Dennett, author of Consciousness Explained. Although this is now at best second-hand and it would undoubtedly be better to go back to the original source, I'll try to recreate the objection as Churchland presented it. Essentially, Dennett argued that consciousness is like a Flight Simulator. I don't know why he chose a Flight Simulator; he really meant any software program. The argument was that the flight simulator creates an image of a plane: the runway under the wheels, the throttle, the acceleration, all the gauges. But it's impossible to understand these images by looking at the wiring of the computer; while we refer to the images as though they are real, there is nothing real about them, and it makes no sense to attempt to explain them by looking at something real (questions about what is real aside for the time being). In this vein, it makes no sense to attempt to explain "consciousness" or the filling in of the blind spot or the hearing of a tree falling in the forest by looking at neural activity.

Actually, as I write this now, it seems even less convincing than when I read it, so I'm probably missing something important. Churchland raised some good counter-arguments to it, but I don't think I fully understood them on a first pass. It seems to me, though, that there's some fundamental problem with the analogy. For one, of course, the images created by the flight simulator are not in the computer; they're in our heads, so they can't be to the computer what perception is to us. We've already seen other reasons why current computers are bad analogies for the nervous system: passive current flow versus digital information, for example.

Anyway, this is just another interesting way to look at questions we've already looked at and continue to look at. It definitely relates to the tree question, too. Of course it makes no sense to investigate a flight simulating program by looking at the wiring of a computer, but it may still make sense to understand the images by looking at our wiring, just as it may not make sense to question the reality of sound, but it may still make sense - even more sense, in fact - to understand the sound in neural terms.


Name: Claire
Username: cwalker@brynmawr.edu
Subject: Magicians and Lateral Inhibition.
Date: Sun Apr 1 16:57:41 EDT 2001
Comments:
I was looking at some websites on Lateral Inhibition and many of them had similar "experiments" to the ones that we conducted in class. One had Hermann's Grid which was a similar test that was possed in class, about looking at a dim star in the sky and seeing it disappear. This grid was black squares on a white background and it seemed like there were gray squares on the white but when you looked directly at the gray it disappeared. It has to do with the ability of the eye to discern the light and dark on the page. I found an interesting reference to magicians on one of the pages. It said that by 'understanding' lateral inhibition, magicians are able to trick us into believing that they are creating magic. An example was the levitating person routine, which will always have a shiny platform (with white cloth and other shiny light reflecting materials) and then the background (behind the table) will be black. This is so our eyes can't 'see' the wires and poles elevating the person off of the table. I found this very interesting. There isn't a way for us to get our eyes to see the wires, when there are so many "light reflecting colors" under the person.

I was also looking at an interesting study (published in Development) that focused on the development of lateral inhibition from primary neurogenesis in zebrafish. The study found that competitive lateral inhibition was a way to explain how primary neurons emerge from early proneural cells of the zebrafish. This seemed interesting to me, because it shows that lateral inhibition (and associated genes) play a strong role in the development of complex nervous tissue.

The last thing I wanted to talk about was the issue of a tree falling in the woods. I don't know if I believe that it doesn't make a sound if noone is around. The air molecules are still disturbed and noise is created. I don't understand why there has to be someone present to "hear" the noise. Just because we are not around to experience, does that mean it doesn't happen.


Name: Elizabeth Gilbert
Username: egilbert@brynmawr.edu
Subject: trees falling
Date: Sun Apr 1 17:11:25 EDT 2001
Comments:
Well, I may be being a bit simplistinc here but this is my take on trees falling:

A tree falls and makes a sound because the molecules in the air vibrate. When they vibrate they knock into one another and that is what sound is. The reason we hear it is that the molecules vibrate into our ear are magnified on the timpanic membrane (ear drum) and move on to the cochlea. In the cochlea, the hair cells are moved by the liquid that surround them which itself moves as a result of the vibration of the membrane. When a hair cell moves enough it creates an action potential on the auditory nerve. That goes into the brain and we percieve sound. So all that is really going on is that a bunch of molecules are vibrating when the tree falls. I don't see how one can say that the brain makes up the perception of sound unless I am totally off base on auditory conduction. (It has been 2 years since I studied this stuff.)

Now back to the tree falling... whether someone is there to hear it or not the molecules still vibrate and so they still make a sound. So I say the answer to the question is yes the tree still makes a sound. The only question is does it vibrate the molecules near your ear, not does it vibrate the molecules.


Name: Dena
Username: dgu@brynmawr.edu
Subject: Timber!
Date: Sun Apr 1 17:53:53 EDT 2001
Comments:
When I was a young jr. high student, I was asked the ‘tree falling in the forest and does it make sound if no one is there to witness it’ question. I rolled my eyes at the stupidity of the person asking it and said, “of course there is a sound, sound it caused by waves of molecules disturbed as the tree is falling down and crashing into stuff. Whether anyone is there is not important, the waves are still being produced.” After class on Thursday, I started to think about the other side’s defense.

So the tree falls in the forest and it bumps into things on the way and finally crashes against the ground. Sound waves are produced aplenty and race off in all directions. As you stand there watching this, those waves ricochet off your eardrums etc. etc. (for more detailed description, see Elizabeth Gilbert’s entry) and you hear sounds. Sound to us, is in fact, those waves of molecules as they bounce into each other, traveling from the source of the disturbance to our auditory sensors. It is a perception. Two things are needed to experience the sound, the waves themselves and something that can translate those waves. So without the auditory sensors, will we have sound at all? I tried to envision this. In my mind, I tried to sneak up on a falling unsuspecting tree in the empty forest. To my dismay, I could hear the cracking and snapping every time, the waves are there and the auditory sensors are there and when the two come together I hear sounds. To try to prove or disprove this query is impossible because we experience sound the moment we look in on the falling tree in the forest. And if we don’t look in, how will we know?

But that isn’t important you say, the sound waves are still being produced where we are there or not. So what if we don’t experience the sound, mechanically, it is still there. Well, mechanically, the waves are there, but sound to us is what we make of those waves. Without something that can translate, or even sense those waves, we don’t hear sounds. So does that mean in the forest devoid of witnesses (human or animal), the tree only makes the potential for sounds but not a sound? I enter the forest of the falling tree, this time I am deaf. The tree falls and I hear nothing, though I know the waves are there, I just can’t pick them up. Maybe there is no sound when there is no one to perceive it, after all. If there is nothing to sense the waves that would be sound, the waves won’t be sound.


Name: Meghan
Username: mshayhor@brynmawr.edu
Subject: reality
Date: Sun Apr 1 20:27:53 EDT 2001
Comments:
My initial response to the question of whether a tree falling in a forest and no one is around will make a sound is of course! But after class on Thursday and more thought on this question I now see the implications of answering this question either way.

The answer to this, one of the greatest philosophical questions, depsends on how one perceives reality. If reality is independent of perception, then the tree in the forest will make a sound regardless of whether someone is there to hear it or not.

However, when considering reality to be determined by one's perception, then the tree did not make a sound when no one was present in the forest to hear it. Hence, the way we perceive sound is just like the way we perceive color, both are functions of the brain.

When a tree falls in the forest, sound waves will always be created. If we aren't there to witness the tree falling, then the sound waves are just waves and will not be translated into sound. It is interesting to think that sound depends on us. If we are not there, then sound (or noise) will not exist. What about animals- does a different type of sound exist for them? Animals must then perceive a different type of reality than we do. But then whose perception of reality is more accurate?

I guess the same arguements that are made for sound and color can also be made for silence. Silence must also then not really exist, it must just be a clarification for us of what we cannot perceive.


Name: Sarah
Username: smccawle@bmc.edu
Subject: Tree falling
Date: Sun Apr 1 20:50:41 EDT 2001
Comments:
I am going to take up where Claire left off. I was also contemplating thhe possiblity of the tree falling and whether it makes a sound, but I wanted to explore the aspect of someone who is deaf. So if there are two people in the woods when a tree falls and one is deaf and the other isn't, does the tree make a sound? If you were deaf, you might argue that the tree did indeed fall, but without a sound, because you didn't hear anything. On the other hand, if you were not deaf and you saw and heard the tree when it fell, you might argue that it did make the sound. Going from these two points of view, it seems to me that the sound produced is based on perception. If you can not percieve sound, then a tree falling will never make a sound, but if you can then that tree will make a sound.

So what happens when no one is around? Does it really matter? If you or anyone is not there to witness it, does it really have any effect? Isn't this what perception is all about? You have to be there and experience it for it to carry any meaning. If you aren't there, then whatever sound it makes while moving the molecules of the air and those that compose the tree is of little consequence.


Name: PaShawnda
Username: pbriley@brynmawr.edu
Subject: silence
Date: Sun Apr 1 21:01:05 EDT 2001
Comments:
It is interesting to try and understand whether one hears a tree fall or not, in terms of silence and reality. I think of reality as independent of my perceptions, and my brain attempts to comfort myself by making up sections of reality that we can't see. Since sound is a disruption of molecules in space and time- this to me is apart of reality, but objects in the world are constantly moving. If things in the world are constantly moving and you believe that reality is seperate from your perceptions, then there would be no silence, right? But silence is too important for me to believe that it doesn't exist. Maybe silence is an absence of our perceptual mechanisms at work, and perhaps it has a regulatory mechanism that makes it block low disturbances, like selective hearing.
Name: Alexis Webb
Username: awebb@brynmawr.edu
Subject: The Pinball Wizard
Date: Sun Apr 1 22:47:01 EDT 2001
Comments:

It seems that most people see perception in terms of all the senses. We are dependent on touch, taste, sight, sound, and smell to understand the world around us. Whether this reality is independent of our perceptions (existing outside of us, not just "the picture in our brain") is still debatable in some of our minds. In talking about the tree falling in the woods question several people brought up the possibility of a deaf individual being present when the tree fell and the implications of this. Such a situation got me thinking about The Who's rock opera "Tommy." In it, the main character, Tommy, witnesses a traumatic event which renders him deaf, mute, and blind. He is a lost cause for his family until one day his cousin places him in front of a pinball machine and low and behold, he's amazing at it.

So, rock music and fantasy aside, what does "Tommy" have to do with anything we're talking about? Tommy is left with touch, taste, and smell... senses that would not seem to be good for pinball playing, a game that utilizes hand-eye coordination. Tommy's perception of the world around him does not include the blinking lights or the flippers of the pinball machine. And, as with the tree falling, do these things exist if he cannot experience them? As the song goes, "he's a pinball wizard; there's got to be a twist!" But maybe not. Maybe perception is as much about what isn't there as what is... Tommy's other senses can compensate for what he has lost. He can "see and hear" the machine, probably better in fact, without his eyes and ears. I don't think perception is always about what's in front of you. It's also about the gaps that you have to fill in. If a tree falls and no one hears it, it doesn't make a sound. If a tree falls and a deaf person doesn't hear it, it doesn't make a sound. In the second case,the absence of sound perception doesn't matter. A deaf person could feel the wind, vibrating ground, etc. created by a falling tree. The question is not does the tree make a sound, but does the tree fall at all.


Name: Daniel
Username: dburdick@brynmawr.edu
Subject: OFF TOPIC: The search for a soul
Date: Mon Apr 2 00:05:03 EDT 2001
Comments:
I originally wrote this in another context, but it seems relevant to previous discussions we've had, so I thought I'd share it; feedback is welcome. Actually, it's not as off-topic as it might seem at first; in many ways, it's all about perception and reality, and would have serious implications if you were a hermit. Anyway, it follows:

Thinking about my interactions with every person I?ve met has reminded me of my recent struggle to identify and define a soul. As I?ve pursued my interest in neurobiology and behavior (a pursuit triggered by conventional ?soul-searching,? although the interest was already there), I?ve become increasingly convinced that there is nothing ethereal that determines my behavior or my emotions and nothing internal to Me that will survive my death, the two definitions that I think are most usually used for the soul. Yet I continue to have an emotional need to believe that there is something immortal [a need that seems to be shared by others in Bio 202], that a soul does exist, but that its definition needs to change. My current vision is that if the ?soul? does not exist internally, it must exist externally; and if it?s not specific to Me, it must be shared ? a common soul, if you will. I conceive of the soul now not as something that exists in a person, but as something that exists in the interactions among people. I?m not saying that interacting with people feeds my soul, restores my soul, or has any other platitudinous effect on my soul; I?m saying that the interaction among people is the soul. Moreover, to speak of ?my soul? is, in this construct, no more accurate than to speak of ?my sunlight? or ?my sound;? the soul is simply another input that affects my behavior, just as seeing light or hearing sound affects my behavior. In turn, my behavior also affects the soul, and thus how others respond to the soul, just as clapping my hands or lighting a candle can affect how others respond to sound and light. The effect of my behavior on the soul ? that is, my interactions with other people ? radiates not only through space, but also through time; in this way, it?s as immortal as humanity. My behavior in interacting with people ripples through generations of the soul as a stone ripples a pond. (I think I?m borrowing that imagery from some poorly written, made-for-TV movie I saw once, but it works for the time being. And I didn?t promise great writing here, either.) Individuality is preserved even in this concept of a communal soul because the effect any single person has on the soul and his or her response to the soul may be as unique as hair color, musical preference, or favorite pizza toppings. True, the effect of this soul on any person?s behavior is mediated by neural activity, but its effect seems as real as any other input ? visual, auditory, tactile ? that determines behavior. That?s how I see it now, though it?s likely to change. One of my most firmly held beliefs is that beliefs should be constantly re-evaluated in the face of new information. I should also note that I?ve never formally studied philosophy or religion, so if it seems that I?m passing someone else?s ideas off as my own, it?s only because I didn?t know someone else had these ideas first.


Name: Matt Fisher
Username: mfisher@haverford.edu
Subject: ramblings
Date: Mon Apr 2 14:12:01 EDT 2001
Comments:
The picture in my head is completely unique to my perception of the world. This explains why so many people can see the same thing and all say they saw something different. I wonder if there is any way to make people all perceive the same thing? What would happen if an image were somehow placed directly into the brain and not processed through the eyes? From class discussion this would seem to work. It is the lateral inhibition network in each person that alters the picture in a person's mind. So if that were bypassed it makes sense to me that the picture would end up being the same.

Another issue with the lateral inhibition network is the effect is has upon our perception. It kind of disturbs me that my eyes control so much of what I see. Also, my brain creates the rest of the image. This implies that my brain will imagine a scene I want to see. So the world could be completely different than what I am seeing. What would happen if my lateral inhibition network were changed? Could placing another person's eyes in my head make me see a "new" world?

A lot of questions were raised in my mind this week. I don't know if any of them can be answered, but they do interest me.


Name: Gwen Slaughter
Username: gslaught@haverford.edu
Subject: thoughts on I-function
Date: Mon Apr 2 16:10:40 EDT 2001
Comments:
In last week's web forum someone asked the question, what is the I-Function and why do we need it? I would like to respond to that question. To my understanding, the I-function is unique to humans. It is what separates humans from the rest of the animals on earth. The I-function is necessary because it helps us make sense of our actions.

In class last week we talked about the blind spot in the eye. The blind spot is something we cannot see unless we do specific exercises. On a conscious level, we do not even realize we have the blind spot because our brains fill in the blind spot with relevant information. Other animals have this blind spot, but only humans are capable of understanding why we have the blind spot. Human brains function at a higher level than other animal's brains--this is why our frontal cortex is so big in comparison to other animals. Because of this high level of functioning humans are able to make sense of, talk about and question the blind spot and other processes that occur in our body and the outside world.

Humans are able to make sense of their actions. Humans can think and communicate. This is how I understand the I-function. It is necessary because it helps in understanding our actions, our interactions, the outside world, and ourselves. Yes, there are things are bodies do, such as the blind spot and the brain making up for it, that are not part of the I-function. But, without the I-function we would not be human.


Name: Kate Lauber
Username: klauber@haverford.edu
Subject: Reality?
Date: Mon Apr 2 16:23:56 EDT 2001
Comments:
I'm finding the discussion on the course forum really interesting. In class on Thursday we discussed color perceptipn and the notion of reality. I fall into the camp of not believing that red is truly red, it's an arbitrary determination constructed by the nervous system. What I feel is important though is the correlation involved. Red would not be red in this pseudo-reality, which I guess is reality, if there wasn't almost a correlation of 1 between people on the issue. Yes, while there is some small variation of someone thinking something is black instead of navy blue, it's pretty amazing how our nervous systems coordinate the have this agreement on reality of color and such things.

Do individual differences exist in this making of reality? Does everyone see things a tiny bit differently but the differences are so small that they don't seem to matter at all. How can people vary so much in so many different dimensions yet we all seem to have an implicit feel for what is red and what color grass is? I feel like this discussion lends itself to thinking about creativity. Are those who are creative those who tend to see the world a tiny bit differently, those who vary a little from what our nervous systems have decided upon as reality? Maybe so.


Name: avis brennan
Username: abrennan@haverford.edu
Subject: reception-perception?
Date: Mon Apr 2 17:48:18 EDT 2001
Comments:
I like the idea that we can philosophically challenge the assignment of sensation and perception to neurological processes. While I have enjoyed the arguments of speculations, I think I am still struggling a bit with how exactly this information is being processes. Perhaps I am getting ahead of myself, but it seems to me that after light is received by the eye and transmitted to the brain, we almost immediately experience the phenomenon of recognition. I have a hard time wrapping my mind around the possibility that these connections are so tight that extremely complex orientations of lines and edges are recognized almost instantaneously. Is there some sort of hierarchy that eventually leads a certain contrast of light and dark to be recognized, or are their cells that are specially tuned to recognize each unique combination?

It seems that the ability for humans to recognize faces, even after people have aged and changes, is an argument for hierarchical processing. That is, there is still a pattern of lines and relative light and dark spots that initiates the same sequence of firing which would lead to the same end result—activation of the cells responsible for identifying the face of that individual. However, the speed at which we are able to accomplish this place such serial processing into question. Perhaps more relevant to the present discussion is the question of how the products of lateral inhibition, namely lines and edges, come together to compose images so smoothly? Would an insult to the brain site responsible for this task result in reading/visual processing disorders?


Name: Christine Farrenkopf
Username: cfarrenk@haverford.edu
Subject: vision, reality
Date: Mon Apr 2 19:43:35 EDT 2001
Comments:
I think that we were all shocked to learn last week that the brain “makes up” information in order to cover up the blind spot of the eye. This week’s lectures about the lateral inhibition system surprised me even more. It is jarring to know that what we previously thought to be “reality” is in fact information that has been altered by the brain. Now that we know that the brain actually “throws out” information and then rebuilds a picture based on contrasts, I am interested to know how the brain accomplishes such a task. What exactly is happening at the neuronal level to allow for the filling in of gaps around the existing contrasts?

While I was thinking about our difficulties seeing at night because of the lack of cones at the fovea, I began wondering about how night-vision goggles work. I think that they are based on contrasts (so that you can see outlines of objects). How exactly does that work?

And about the tree falling in the woods . . . We said that color is a function of the brain and not a physical reality. Then we are said that sound is only a physical reality when there is an apparatus to interpret sound waves (an ear). So is light (and not just color) itself not a reality if there is no eye for it to enter? This is hard for me to understand. Is something only “real” if our I function is aware of it? For example, if we have an X-ray, there are X-rays travelling through our body, even though we are not aware of them (ie, we cannot sense them moving through our bodies). Does that mean they are not “real”?


Name: Euree Choi
Username: echoi@brynmawr.edu
Subject: Reality...
Date: Mon Apr 2 20:21:21 EDT 2001
Comments:
Reality is actually an array of lines and edges that are compared and contrasted with other lines, edges, or shades to perceive the world. How did these lines and shades ever even come to be perceived as objects in the first place? The fact that our brains fabricate information to fill in the gaps is quite intriguing. The same principle probably applies for speech. We probably fabricate certain phrases to fill in the gaps without even being aware of it. However, fabrication relies on experience. Is the I-function necessary in this case? Like we had discussed in class, we may need the I-function in order to learn new concepts that allow us to fabricate what had been experienced previously.

To clarify the question of the falling tree, I had discussed the issue with a philosophy major. Philosophically, there is no true answer to the question, "If a tree falls in a forest and no one is around, does it make a sound?". A constructionist believes that individual perception is reality. In order to perceive that the tree made a sound, the individual has to have experienced the sound at the moment the tree had fallen. Contrarily, a realist believes that the acknowledgement of a falling tree making a sound is reality. The fact that sound waves are produced as the tree hits the ground and our experience of knowing that a falling tree creates sound sufficiently explains that there falling tree produces sound. What if a tree falls next to a deaf person? Would he/she hear the falling tree since he/she could at least feel the tree falling?

Sound by definition is heard. Thus, I am not sure what I believe but the ideas are definitely fascinating to me.


Name: karen munoz
Username: kmunoz@haverford.edu
Subject: perception vs. reality
Date: Mon Apr 2 21:03:13 EDT 2001
Comments:
Meghan's comment about silence is really interesting, about how we describe what we perceive as the absence of sound. i believe it exists and i liked PaShanda's description about how it is "an absence of our perceptual mechanism's at work." because what we describe as reality is only what we receive in input and there is much that we do not "experience." but how do we describe the reality that we cannot perceive, and what is it that we do not experience. broken down in terms of mechanisms of sound and the way that the waves vibrate in our ears, then we (our ears) are required for the sound to be heard, but the waves still moved. what do we call the disturbance in waves that a tree makes if not sound? the color blind person cannot distinguish between red and green, but the non-color blind person can. the light reflects differently, and he or she can see the difference. is it reality that the colors have the potential to reflect light differently? ahh, so many questions about reality/perception/mechanisms to answer . . .
Name: Nana
Username: ndawsona@brynmawr.edu
Subject: What is Real?
Date: Mon Apr 2 21:21:14 EDT 2001
Comments:
The question of whether a tree falling in a deserted forest makes any noise or not is one of those philosophical questions that I think can go either way. Some people may say that it would not make a sound because no one is around to hear and validate its existence. But this then suggests that things do not exist unless they are being experienced by some living creature and that in order for things to be "real", they must be perceived. But it is hard for me to believe that something would cease to exist if I was to stop thinking about it. It was disturbing to discover last week that my brain can disregard an entire portion of the world around me, and it is too much for me to believe that just because I'm not around to hear that tree falling, it does not make a sound.
Name: Irma Iskandar
Username: iiskanda@brynmawr.edu
Subject: Tree Falling
Date: Mon Apr 2 22:38:22 EDT 2001
Comments:
Reading through the class entries, I am impressed at the mainly unionized opinions people have regarding the tree falling down scenario. This is not an unfamiliar scenario, for it has been brought up time and again in my philosophy classes - now, however, with the extra twist of the mind perception, which accounts for lateral inhibition and color processing. These are the ways by which we learn anything at all, for by perception, this is how we can interact with the world. These faculties that we have are ultimately dependent on perceptions in order for us to make sense of much at all. Therefore, if a scenario occurs where there is no perception for me to behold, then there is no basis for me saying that there was any reality in that scenario in the first place. There was no way for me to establish the fact that the sound could continue on without my presence. "Of course the sound would continue on", I would say indignantly, but then I wonder WHY it is that I expect the sound to occur even if I am not there to receive it.

The answer could be very philosophical indeed. As we have learned in empiricist texts, we believe that the sound would continue without our presence because we have this feeling of EXPECTATION due to our past observances. We walk out of a room with the radio on, and enter 10 minutes later, expecting the radio to still be playing sounds. This is only because we must believe in the continuity of things, in order to make much sense of the world and to make the world seem less random. It all comes down to pyschology and how our brain functions. It always comes back to the brain.


Name: Camille Sinclair
Username: csinclai@brynmawr.edu
Subject: falling tree
Date: Mon Apr 2 22:38:25 EDT 2001
Comments:
I agree with the majority of responses to the "tree falling in the forest" scenerio. I don't want to reiterate everything that has already been said but here goes...the tree falling results in vibrating molecules that enter the ear and is magnified in the eardrum to enhance various sounds. The vibrating molecules are there regardless of whether an individual witnesses/perceives them. Someone above brought up a great point that if they were in the forest w/ a deaf friend as the tree was falling the deaf friend would not hear/perceive the tree falling as the hearing person would. So, the fact that the deaf person is not receiving the auditory stimuli does not mean that it is not there. By extension, the fact that no one is present to perceive the sound made by a falling tree does not mean that it did not make a sound.
Name: Alice Goff
Username: agoff@brynmawr.edu
Subject: Restoring Color
Date: Mon Apr 2 23:08:33 EDT 2001
Comments:
Class on Thursday left me a little down on life. What's the point of anything, if in reality nothing has a color? Tropical fish, tomato sauce, my favorite tye-dye tee-shirt are all simply a trick of perception. So, I embarked upon a path of rationalization for maintaining enthusiasm for our supposedly colorless world. I began thinking, what is this reality business? How can we speak of a reality other than that which we percieve? True, as we proved in class, we can concieve of that which we have never experienced, but can we concieve of a reality that we cannot percieve? I would argue that we can't. Inherant in the act of imagining is a 'picture' in our minds, and that picture cannot be there without perception. Imagining a world without color involves a visual precept-- we cannot talk about a reality which we cannot percieve.

So, in regards to the tree falling in the forest: my take on the situation is that when no one is there, the tree does not fall at all. There is no tree. Reality is perception, without that, nothing exists to us.

I'm way out on a limb here. I am prepared for the limb to break and the tree to fall.


Name: Kristine
Username: Kristineh44@hotmail.com
Subject: The tree
Date: Mon Apr 2 23:21:06 EDT 2001
Comments:
I, too, was one of those people sitting in philosophy class completely unimpressed with this whole tree "dilema." The answer seemed painfully obvious. Why wouldn't it make a sound? I was not, however, considering the reality of sound as being in any way contingent upon the accuity of inner ear workings but I can now see how this component does indeed create a puzzle. It's another one of those strange situations in which more information makes me feel more confused! But anyway, I agree with Meghan in that this issue has something to do with how one perceives reality, mainly whether or not it is independent of perception. Intuitively, I want to say that reality is, or at least should be, independent of perception. I mean, if perception, as it has been known to do, obscures "truth," if reality is truly objective....

Somebody else suggested that this tree is perhaps of little consequence if we are not actively perceiving its activity. Why have this headache over rustling branches if they are not crashing through our living room windows? But don't things happen every day, every minute, that affect us without the immediacy of direct perception? And it still seems strange to claim that people determine reality in any manner that could be deemed objective. The only solution I can see right now is to allow for several different planes of "reality," some of which depend on an organism's sense as an mediating variable.


Name: ingrid
Username: ladybasti@aol.com
Subject: reality
Date: Mon Apr 2 23:36:56 EDT 2001
Comments:
If reality is already so blatantly influenced by the simple way the neurons fire and the way our brain is put together (the portions of us without the 'I function')....I'd really hate to see the relationship (on some measurable scale) as to how distorted reality is by the 'I function'. It seems like it should be obvious, that the 'I function' is a natrual distortion of facts. But now that we've seen that even the facts themselves are distorted. Ugh.

I think the topic of the tree falling in the woods is extremely interesting. And I'm not sure which side I lean towards. However, the example of a deaf friend being with you and how that could skew our answers is hard to see... because actually, the deaf friend has other ways of perceiving it as falling (sight, the wind brushing against him/her when it fell, etc.) However, I'd like to draw another parallel.

in the middle of class, we talked about how there are portions of the world that we don't percieve because we don't have cells to perceive them. Well, there has always been the debate of paranormal phenomenon. What if some people have the senses, to see and hear things like that. Most of us don't, and we consider ghost stories (etc.) to be totally untrue. Could this be simply another version of the tree in the forest? What if we don't know of this whole other layer of reality. We already debate whether its real or not... same thing.

That was just a weird parallel that came to me. Just a thought.


Name: jenny
Username: jecohen@brynmawr.edu
Subject: tree in the woods
Date: Tue Apr 3 00:03:09 EDT 2001
Comments:
Okay, if sound is the name that we've given to the disruption of air (or whatever) particles that is caused by one object coming into contact with another, then yes a tree falling in the woods makes a sound whether you're there or not. As for the idea about the deaf individual and one who can hear, a deaf person can sense sound in the vibrations it creates, which they can feel. In other words, if a tree falls in the woods and a deaf person's around to "hear" it then it does make a sound. The sound is felt rather than heard, but it still exists.

What is really interesting to me is the idea that reality is in a sense now, completely subjective. If reality as I know it is only my brain's interpretation of reality, then this leads to some interesting questions about things like, I dunno, drugs. We've all heard stoned people say that they experience reality differently while they're high. Is their reality not real simply because it is caused by a reaction of their brains to the drug? I mean, everybody's brain functions differently anyway right? What is percieved as reality by my brain when it functions normally is very different than that which is percieved on a normal basis by say an autistic person, or a blind person, or a person who routinely suffers from hallucinations, or someone under the influence of drugs. Who's to say that my brain got it better than the autistic kid's or the blind person's or the stoner's? I know I'm probably wrong here, but it's possible then to think that a reality experienced under the influence of drugs may be no less valid (no more off from the truth) than the "reality" we experience every day.


Name: caroline ridgway
Username: cridgway@haverford.edu
Subject: thoughts
Date: Tue Apr 3 00:39:09 EDT 2001
Comments:
I had a truly liberal arts moment this afternoon, the kind when it all comes full circle. I was sitting in my philosophy class trying to digest the discussion on Kant and his treatment of experience and perception, when all of a sudden the professor began talking about color and sound perception as a way to prove his point. First, he held up both a green computer disk and a black one, and asked us whether the disk being green or the disk being black were a function of the object itself, or rather just of the way we perceive those objects. Leaving that behind, he asked the ubiquitous "tree falling in a forest..." question, hoping to achieve the same end he did with the disks. Kant's whole argument rests on the notion that, in as much as we are aware of it, the world around us exists only as it appears to us, that it is only through intuition that leads to judgment and subsequent understanding that experience can be subjectively had, with the "I" consisting of the subject to which the objective world appears. I found it remarkably fascinating that, even today with our sophisticated knowledge of how rods and cones work in the eye and how sound waves vibrate in the ear to create sound, we are still arguing over the same dilemmas as plagued Kant and other philosophers. That, to me, seems ample evidence for the proverbial wool that has been pulled over our eyes by our respective "I" functions or nervous systems or whatever it is that convinces us that reality is real. That we can rationally know that a tree falling in the woods creates disturbances in the air that only amount to sound as we know it if something with ears is there to be impinged upon is not, generally speaking, enough to keep us from feeling like we have been slightly betrayed when we truly stop to consider that concept. Things like hearing a tree crash to the ground or seeing different colors in the world around us appear to us as valid distinguising markers of our environment. And this is necessarily so insofar as this false positive read on the things we perceive allows us to negotiate our worlds in a consistent and safe manner. But it does make you think... We really are only vehicles for sensation. All that we think we experience is really happening only incidentally, and it is only that our eyes or ears are in the way that causes that occurrence to suddenly take on the dimension and complexity and emotional and cognitive loading of an experience. To speak with the hubris that so often characterizes man (or woman), it is almost as if, as far as we are concerned, the world ceases to exist if no one or no thing is there to experience it. You close the door or turn your back and color and sound and smell and touch cease to be. And yet we have such a vivid image of that world we just turned our backs to. Which is "real" - the picture in our heads that guides our actions and beliefs or the one that exists independent of our perception, waiting for an itinerent eyeball to paint its picture?
Name: Nazia
Username: nahmed@brynmawr.edu
Subject: a tree falls
Date: Tue Apr 3 00:57:27 EDT 2001
Comments:
Interesting question.... My first instinct to the question was YES. Of course a tree makes a sounds when it falls regardless if anyone is present to experience it. I'm not going to go into detail of this as it already has been said. Does my thought make a "thought" if it isn't said or written? Not sure if that makes any sense but that just occurred to me. I think the larger question is exactly how we define "sound." Can we only define sound if it is heard? And if so, who has heard it or even what? If we say that the tree does not make a sound then do we categorize sound as everything WE perceive? Perhaps the tree doesn't make a sound unless the sound is actualized… some questions that were floating in my head.
Name: Niru Kumar
Username: nkumar@brynmawr.edu
Subject: glasses
Date: Tue Apr 3 01:52:00 EDT 2001
Comments:
I was pondering the I-function and how it fills in the gaps of perception, left by blind spot. How does the brain really know these things are real? This idea really bothered me. Then I was reminded of one of the first examples we talked about in class-the upside down glasses. After wearing glasses that invert images for a while your vision inverts itself to make your sight match reality. The brain seems to take it's cues from corollary discharge from other senses. Gives me more faith in myself.

Even though lateral inhibition of our visual system making reality defined by the edges, it doesn't mean that this view is wrong or skewed. Our brain is capable of taking these factors into account and matching them up with reality. Lateral inhibition shows that the nervous system has a certain set of assumptions it works with. But, the example of the glasses shows that this is elastic if the nature of 'reality' changes.

The notion of a tree falling in a forest with no one around is really a question about the nature of perception. Is sound really only defined by some hearing it? Is it just sound waves then? It depends on the definition of those terms. Yes, what each person hears may be interpreted slightly differently, but the basic cause is still the same reality. And, if the sound heard does not correlate to reality then your nervous system corrects for it or it shows up as a defect. I'm not sure if I accept the definition of things like sound and color as subjective to our individual biases dependent on our perception. These things exist outside us, and our convention of referring to them doesn't mean that is the only way they exist. If the word 'dog' had no reality associated with it then dog would have no meaning. Thus, dog is tied with reality, just as our associations are. Calling them our associations does not make the reality any different without the name.


Name: Caitlin Costello
Username: ccostell@haverford.edu
Subject:
Date: Tue Apr 3 02:47:23 EDT 2001
Comments:
Although I tend to agree with the idea that reality is defined by our perception of it, I am still tempted to say the tree still does make a sound if nobody is there to hear it, because it still produces "sound" waves. Since there are lots of other kinds of physical waves that we have no way to directly perceive, and still don't doubt that the waves are there, I can't really deny the presence of these waves. And if we call them "sound waves" when we can hear them, I dont know why we would call them anything different if we can't hear them. So I suppose it depends on how you define sound, but the definition that still makes the most sense to me leads to the conclusion that the tree still makes a sound.

A similar thought experiment I have heard is, imagine there is someone who sees every color as its opposite--that is, green as red, yellow as blue (are those opposites?), etc. She has learned to call the grass "green" even though she sees the color the rest of us think of as red, because for her red has always been called "green." So the question is, would she have any way of knowing the difference or having it explained to her? Would we? Is it possible that half of us really see green as red? Does it matter? An interesting idea, i think....


Name: Andrea
Username: n2tiv@aol.com
Subject: experience = existence?
Date: Tue Apr 3 06:37:29 EDT 2001
Comments:
OK, I hope Im not beating a dead horse by putting my 2 cents in on the proverbial tree falling in the forest, but here goes....Its just that I wonder how far we are willing to take it. If a tree falling in the forest has no sound unless someone is there to hear it, isnt what we are saying that there is no objective existence of "sound quality" apart from the EXPERIENCE of it? are we also willing to say that there is no smell aprart from my experience of it, no light apart from my experience of it? How about this one, no object apart from my experience of it? This may sound absurd but I think Berkely's arrived at his radical stance that nothing exists & there is only experience, starting exactly where we are now if we propose there is no sound apart from the experience of it.
Name: Sadie
Username: siwhite@brynmawr.edu
Subject: trees
Date: Tue Apr 3 08:49:47 EDT 2001
Comments:
I'm still in complete agreement with the idea that trees are silent if they fall in the absence of human ears. What we call sound, just as what we call sight or taste, is only our brain's interpretation of the various inputs it receives. What I think is most interesting, though, is that this completely contradicts the philosophical ideas of absolutes. As some members of the class discussed last week, it is a philosophical tradition (often a comforting one) that absolute truth exists. That is, there are certain things that exist currently outside the realm of human comprehension that are unchanging and concrete, and, if humans cannot grasp them, it is due only to the limitations of their humanity. However, our course takes an opposite stance, rooting itself in what humans CAN understand, and assigning all else to the soon-elucidated future. I also can't help but think of Ayn Rand's The Fountainhead when I consider the idea that man dictates reality by his own mental acrobatics. Perhaps science is the ultimate form of humanism, as Rand's book claims that all of man's creations are?
Name: isabella
Username: izzy98@aol.com
Subject: reformed idea
Date: Tue Apr 3 09:06:56 EDT 2001
Comments:
One idea reformed... I used to think that if a tree falls in the forest and no one is there to hear it that it does make a noise. I guess I believed that even if a human is not there to hear then an animal is there to hear it. At that time I assumed that all creatures "hear" the same way. I never really thought about the fact that it is OUR brains that create the perceptions that we call "hearing" and "sight."

Hmmm...i'm still churning that idea in my mind, wondering what other conclusions this will lead me to


Name: sural
Username: skshah
Subject: reality check
Date: Tue Apr 3 09:19:37 EDT 2001
Comments:
In reading the above comments, I still want to support the whole "of course the tree makes a sound" argument, even though there have been many convincing arguments against it. What causes me to continue to feel as if the tree does make a sound is a parallel thought concerning "reality." As a few others have begun to mention, there is a second question at hand here: If a tree falls in the woods and no one is there to hear it/see it/sense it, has it really fallen at all...?

To me the answer is yes---somehow, I feel that it would be entirely too self-centered of a view to be of the opinion that the tree waits to fall until just before I approach it to sense its falling. I know that this statement sounds a little extreme, but how else can you explain my perception of the a tree that has fallen that has been upright the last time I had seen it? Obviously, I must think to myself that something must have occurred between my two viewings of the tree to have caused it to fall-- does that mean that I think that it only happened at the point wheen I could perceive it?? NO. It could have happened anytime. Along with this conclusion comes the implication that it is possible for "stimuli" such as light, sound, smell, etc. to occur with or without the presence of a human being to receive them.

Maybe I'm way off here, but it seems relatively logical to me....


Name: Mary
Username: mferrell@brynmawr.edu
Subject: Color and "I"
Date: Tue Apr 3 09:32:05 EDT 2001
Comments:
Action potentials travel from the retina to the primary visual cortex of the occipital lobe. If this firing happens in response to colors a section known as V4 becomes active. If there is damage to this area on one of the hemispheres, the person will see only in black and white on that opposite side. There world will be perceived half in black and white and half in color. If there is damage to both V4's on both hemispheres then the person will become totally colorblind, everything is seen in black and white.

With bilateral damage not only is the person now void of perceiving colors but also unable to remember or imagine colors. The memory of colors is gone. The experience of color is no longer a part of the "I" function, the consciousness.

This leads me to think of the "I" function as--not only a box but something with tentacles throughout the nervous system.


Name: ingrid
Username: ladybasti@aol.com
Subject: never the same reality
Date: Tue Apr 10 01:37:27 EDT 2001
Comments:
Is it possible that since there are slight possiblities of variation in almost everything in the world, that we may not perceive everything we perceive exactly the same as everyone else? What if everyone's 'yellow' was not the Same as my 'yellow' because our neurons fire just a little differently. Since I'd always been labeling yellow as yellow, than I wouldn't really know if the other person actually Saw the same thing as me.

What if this were particularly true for sound (since it's so variable). What if people don't hear the actual same thing as everyone else heres. We would Think that we do, but we'd never really know. Perhaps this is why some sounds are totally unpleasant to some individuals and peaceful to others. Perhaps its not taste, just science.


Name: Henrike Blumenfeld
Username: hblumenf@brynmawr.edu
Subject:
Date: Wed Apr 11 13:01:31 EDT 2001
Comments:
Reading these comments on whether the tree does make a sound or not, I'm thinking about the book "Flatland": in a geometric world of points, lines, 2D surfaces and 3D objects, all these entities have different perceptions of each other. For example, a dot is lined up with other dots on a line. Yet it can never perceive the line since to both of its sides there are only dots. Either 'real' dots, of other entities that cross the line. In this thought experiment absolutes do exist, but they can only be partially perceived, depending on the 'level' the perceiver it at.

Say then that the tree falls, and it causes air compressions (and anything else we might not be aware of), sends some kind of signal. The observer walks by, his/her capacity to perceive is able to pick up part of this signal and interpret it, and s/he calls it 'sound.'

Then, what about this one? Yes, the tree makes a 'sound' as it falls, but it really makes so much more because who knows what else is in that signal. If the point in Flatland observes another 'point'which is really a line, then if the observing point is not there to observe the 'point,' the 'point' becomes a line. So there's an argument that the tree doesn't make a 'sound' when without the observer.





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