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Upside down, round and round
Through the Looking Glass: Is the distinction between "real" and "virtual" image real?

Where should this thread be placed? Cognitive Sciences, along with my other threads about vision and other brain processes? Or by Physical Sciences, along with the countless myths on which contemporary science is built?

Light is a subjective phenomenon, only known to living creatures as far as we can tell. But it is also a physical phenomenon that stands at the basis of modern science. The way physicists understand light is since du Broglie (1925) the way they understand matter. From gravitational waves to an expanding universe, all depends on how we interpret light phenomena. To change the perception of light in science is to change science itself.
However tempting that maybe, my objectives are much less ambitious.

Allow me to start with a simple mirror and invite you to step inside with me. Who knows? Maybe we will encounter Alice in our journey. Just as long as w ... (read more)
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[pagination is given as page number in pdf file/page number in original text]
Chapter One
The first lines sound very strange coming from the founder of wave theory since they consecrate the standing of the opposite view, Geometric Optics:
"As happens in all the sciences in which Geometry is applied to matter, the demonstrations concerning Optics are founded on truths drawn from experience." Huygens sees therefore no conflict between his new approach and Optics which are based on the behavior of particles of light. Einstein's wave-particle duality was certainly nothing new!
Huygens therefore does not doubt the validity of optical laws that say that light travels in straight lines, that the angles of incidence and reflection are equal or that refraction obeys the law of sines.
That is all and well, but what is the relation between those particles that make up light, and those waves that the same part ... (read more)
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How are we to go about evaluating the meaning of a work of art, which in our case is a subset, namely a literary work? In the middle of the 20th century literary criticism was very dependent on the concept of author intention, the notion that the meaning of a literary work was found in the author's view of it, either when it was written or later. This view suggested that authorial intent is paramount in the interpretation of a work's meaning.

This concept was challenged by a revolutionary paper published in 1946 by W.K. Wimsatt and Monroe Beardsley entitled “The Intentional Fallacy”. The notion behind this essay was that the meaning of the work was not necessarily what was in the writer's mind at the time of writing, or later, but was more to do with what the readers of a work see it as. This argument was advanced by American New Criticism amongst others.

The tenets of "The Intentional Fallacy" have been questioned by a number of people. For example Hirsch has suggested that t ... (read more)
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[First, some considerations concerning a general neural process.]
The Myth of Synaptic Efficacy
This is a widely spread belief that has probably its origin in Shannon's information theory indiscriminately applied to neural processes. Once this view is rejected, the idea that  "[t]he extent to which synaptic activity can signal a sensory stimulus limits the information available to a neuron" (Arenz et al "The Contribution of Single Synapses to Sensory Representation in Vivo", 2008) loses any plausibility. (my emphasis)
What can be rejected for the brain as a whole (see the entry "Do we get too much information?" in my thread Retina: Miscellanious) can certainly be put in doubt when dealing with (individual) neurons.
Many concepts related to synaptic efficiency are likewise taken as dogmas, one of them being the probability of secretion of neurotransmitters that is supposed to be enhanced or reduced according to the circumstances. Such a concept, which is obviously a statistical instrument in ... (read more)
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A first intuitional approach

Movement is a very old metaphysical problem that divided the great ancient Greek thinkers.
Zeno's paradoxes, as discussed by Plato, Aristotle and others, found their way in modern thinking in the form of calculus, relativity, and last but not least, in the neurological underpinnings of motion perception. I will confine myself in this thread to the latter aspect, with only brief remarks concerning the others. Both the physical and philosophical traditions are rich in debates that would take many volumes to treat properly. 

The idea that we are always looking at a stationary picture of reality (in which stationary objects remain in the same place relative to the visual scene they are part of), and that the sensation of movements comes from the differences between two consecutive images is, very often, the implicit assumption of the 'scientific" approach to motion perception. 
I need to be very clear on this point. In my view, it is not the calculation of these d ... (read more)
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Inhibition is a typical homunculus concept. It creates no problem when considered as an active reaction of the organism (stopping a movement to change directions for instance) since it would have a definite neuronal target. But how can the brain decide which neurons to inhibit when (primarily) engaged in the excitatory stimulation of other neurons? To go back to our previous example, how can the brain stop the stimulation of all memories that have something red in them?
Obviously it cannot. We have no control over which associations are activated at any time. We have all experienced moments when we were really grateful that nobody could read our mind because of the embarrassing thoughts or images that would just pop up in our consciousness. 
That does not mean that there is no (unconscious) inhibition at all. Maybe the embarrassing associations have been let through for reasons irrelevant to our problem now, but that at the same time many other memories were stopped from popping up. Stil ... (read more)
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I cannot ever hope to treat of all important issues concerning the retina, so there will always remain things to add and others to reconsider. I propose to use this thread for just that, as a container of unresolved questions that need more work. I will try to use no more than a single entry for a single issue.

What does convergence in the retina mean?
Assuming I am on the right track, and that neurons do not hide any mysterious, computational, codes, then it is obvious that converging inputs can only affect the intensity of the original input, either by enhancing it, or by reducing it. It also means that rods nor cones can contribute their spectral influence (including gray shades) on the receiving cell. After all, color sensitivity has already disappeared from view, making room for mere intensity related effects, including changes in membrane conductance.
A simple scenario would make it so that receptors, via the intermediary neuronal layers, are already wired together in spatial config ... (read more)
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I would like to present a short and general review of a book treating of low-level processes concerning neurons. This book raises many questions concerning the nature of sensation, and its philosophical, theoretical and methodological consequences. I propose to to leave the discussion of the questions to after the analysis of these low-level processes, and the assessment of their general significance. I think it is very important to lay down a scientific foundation for the discussion, and that can only with a thorough understanding of the chemical processes that determine the neurons's behavior, and ultimately, that of the brain as a whole.
I am assuming that this book is representative of the current scientific view on the relevant chemical processes in the brain, and does not present a controversial, or obsolete, interpretation of said processes.
As will come clear by reading the following lines, this book present quite a challenge for the conceptions I have been developing, concerning ... (read more)
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I was (re)reading Weiskrantz' 2009, "Blindsight", trying to make sense of the different areas that were involved in this peculiar case of vision. I had tried to do the same earlier with Prosopagnosia 
[too many articles to mention, but it started with Gross, a graduate student of (who else?) Weiskrantz, Gross et al, 1972 "Visual properties of neurons in inferotemporal cortex of the macaque", and certainly did not end with the objections of the Tarr group against the specificity of this ailment, Gauthier, Behrmann&Tarr, 1999, "Can face recognition really be dissociated from object recognition?". The debate is still alive and kicking: Richler et al, 2012, "Holistic Processing Predicts Face Recognition".]
also to no avail. My frustration had almost reached a boiling point when I realized that it really did not matter where those phenomena are situated in the brain. Even if I believed in computational modules (or even computational neurons), which I most certainly do not, then I would still o ... (read more)
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Does anyone have any information of a good source/information on Dorothy Parker? (author)I am looking at her in comparison to Friday Kahlo's journal writings.
Would be grateful for any help.

The idea that the results of Hubel and Wiesel are flawed (see last two entries in my thread "Lateral Inhibition and Receptive Field") will certainly evoke a lot of resistance. After all, I am not talking of inconsequential details that can be corrected by following research. It concerns results and thoughts that have become dogmas in the field: different receptive fields at different stages; hierarchical organization of visual pathways; feature sensitivity; etc. 
So, why does the fact that the results of Hubel and Wiesel are based on retinal stimulations, and not on optic fibers (via the Lateral Geniculate Nucleus) make them flawed?

Imagine the following hypothetical, and unrealistic, example:

Retinal Stimulation :
Optic Fiber Response:
Visual Cortex Response:

[I could not get them all on one line, the symbols got scrambled.]

Such a crude drawing shows that neurons in the visual cortex rotate retinal stimulation, after it has been processed by the ganglion cells, 90 degrees upwards ... (read more)
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The 25th edition of CSW’s Annual Graduate Research Conference will take place over two days, April 23&24, and will feature a keynote address, reception, networking luncheon, workshops, and a poster session.

THINKING GENDER 2015, CSW’s 25th Annual Graduate Student Research Conference, promises to strengthen scholarly networks and inspire lively conversation. To help make this landmark anniversary a memorable success, we have expanded the conference to a two-day schedule at UCLA’s Covel Commons and added a keynote address, poster exhibition, awards for papers and posters, student travel grants, workshops, and more.

We will open the conference with a keynote address, “Body Modifications: Violence, Labor, and the Subject of Feminism,” by Rebecca M. Herzig, the Christian A. Johnson Professor of Interdisciplinary Studies and Chair of the Program in Women and Gender Studies at Bates College (http://, from 2 to 3:15 pm. The keyno ... (read more)

The role of sensation is practically inexistent in the majority of articles based on traditional scientific methods imported from the exact sciences. The danger of artificially obtained data has been recognized lately, and more and more emphasis is being put on the necessity of studying visual processes in situ, or at least in situations as close as possible to the natural environment of animals and humans alike. The authors of "Do We Know What the Early Visual System Does?", ( by Garandini et al, 2005), recognizing this trend, leave no room for misunderstanding:
"We can claim that we know what the visual system does once we can predict neural responses to arbitrary stimuli, including those seen in nature."  Using videos or images of natural scenes poses new challenges to neuroscience. It is a far step away of clearly defined parameters that can be easily quantified. This could be interpreted as an admission of failure of the traditional scientific methods, based on the v ... (read more)
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REQUEST: Please send errors, omissions, and suggestions. I am especially interested in citations made in non-English publications.

I am trying to start a discussion for teaching INSEPARABILITY OF LOGIC AND ETHICS. A COLLEAGUE WROTE: I'm going to be teaching your "Inseparability of Logic and Ethics" in a couple weeks. I was wondering if you had any tips on doing so or thoughts about points to emphasize. I've always loved the paper and found your pedagogical techniques quite helpful.
MY ADVICE TO MY COLLEAGUE: First, before assigning the paper to be read, ask the students to look up “ethics” and “logic” in a dictionary or other reference work and then to write a paragraph on what the two have to do with each other. Second, after the students were supposed to have read the paper, ask them what they got out of it. Just let them talk and prompt them where necessary. No contentiousness. Third, read the first page aloud to them and see what happens. As you go read chunks aloud and ask questions—just like I did teaching you Tarski’s truth-definition paper. Fourth, go around the clas ... (read more)


► JOHN CORCORAN AND WILLIAM FRANK, Cosmic Justice Hypotheses.

  This applied-logic lecture builds on [1] arguing that character traits fostered by logic serve clarity and understanding in ethics, confirming hopeful views of Alfred Tarski [2, Preface, and personal communication].

  Hypotheses in one strict usage are propositions not known to be true and not known to be false or—more loosely—propositions so considered for discussion purposes [1, p. 38].

   Logic studies hypotheses by determining their implications (propositions they imply) and their implicants (propositions that imply them). Logic also studies hypotheses by seeing how variations affect implications and implicants. People versed in logical methods are more inclined to enjoy working with hypotheses and less inclined to dismiss them or to accept them without sufficient evidence.

  Cosmic Justice Hypotheses (CJHs), such as “in the fullness of time every act will be rewarded or punished in exact proportion to its goodness or badness ... (read more)

A very popular text book, Sensation and Perception by Goldstein, states the following:
"Light reflected from objects in the environment enters the eye through the pupil and is focused by the cornea and lens to form sharp images of the objects on the retina."
This is a common view that I have found explicitly expressed in any book or article I have read on vision.
The assumption of a retinal image poses at least two problems:
1) 2D array vs 3D world. How come we see objects in 3D while the retinal image is 2D?
2) The Inverse Problem: different objects have the same projection on the retina, but still we have no difficulty distinguishing between them.
I would like to add a third one. The retinal blind spot.
The explanations I have found have me baffled. The ingenious tests by Ramachandran and others, that purport to prove the existence of the blind spot, only add to my confusion. I have tried to find an answer to a similar problem, Tunnel Vision (Retinitis Pigmentosa), but I did not get any far ... (read more)
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I am working on a paper on photography and memory. The subject is beyond my formal training. I was trained, broadly, in political economy, philosophy of social science and international affairs. In an earlier incarnation, I also worked as a journalist (reporter and photojournalist) and have some formal experience... Would anyone care to read a draft paper and comment or make suggestions, please. I can have the first draft available by the middle of July. It is incomplete at the moment, as I have other work (to pay the rent). Thanks Ismail Lagardien

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