Tag Archives: science

Comunicação Não-Violenta | JC DEBATE


Neuroeconomia: A Tomada de Decisão


Papel da fofoca em nossa evolução


Museum of Science and Industry, Chicago: Review

Chicago Museum of Science presents a Wrong Color Definition

Chicago Museum of Science Color Mistake

According to the Museum of Science and Industry (Chicago, IL) “the color of an object is determined by the specific wavelengths of lights that it absorbs and reflects” but THIS IS NOT TRUE. This wrong definition is presented in the Color Booth and situated in the Science Storm Exhibition. Here are some explanations about why color is NOT determined by the specific wavelengths of lights that it absorbs and reflects:

“Many people believe that color is a defining and essential property of objects, one depending entirely on the specific wavelengths of light reflected from them. But this belief is mistaken. Color is a sensation created in the brain. If the colors we perceived depended only on the wavelength of reflected light, an object’s color would appear to change dramatically with variations in illumination through- out the day and in shadows. Instead patterns of activity in the brain render an object’s color relatively stable despite changes in its environment.” – by John Werner, Ph.D.: UC Davis, Center for Neuroscience.

“While color of an isolated light is closely related to the light’s physical properties — its energy and wavelengths — this is a misleading fact for understanding normal viewing. Color is not in light. What we see depends directly on a pattern of neural responses, not on the wavelength or energy of light that enters the eye. The simple relation between a physical stimulus and how we perceive it breaks down when the light is part of a complex scene. In natural viewing, the whole visual stimulus is a patchwork of different lights from many objects. The neural response to a particular light, and therefore our perception of it, is affected by the context of the other lights also in view.” – by Steve Shevell, Ph.D.: University of Chicago, Institute for Mind and Biology.

“Color is often thought to be a quality of light but this is not so. For example, the expression the ocean is blue uses a perceptual experience of blueness to describe the physical light. Color itself is not in the light. Color is a perceptual phenomenon determined by neural processes in the brain. The region of the electromagnetic spectrum that is visible to humans is from about 400 nm to 700 nm, but no wavelength is endowed with a color. Instead, a particular wavelength, say a wavelength near 470 nm or 580 nm, is perceived as blue or yellow, respectively, only because these wavelengths stimulate the photoreceptors in the human eye that are responsible for the transduction of physical light into neural responses. Those neural responses go through a series of processing stages in the brain. The experience of blue or yellow, as well as all other colors, is a mental construction. The experience of a color is like the understanding of language. There is no meaning in the physical sound (the brain must interpret it) just as there is no blue or yellow in the wavelengths of light. Color is a percept that humans are able to experience through sensory neural processes.” – by Claudia Feitosa-Santana, Ph.D.: Roosevelt University, Psychology Department.

This is very old news:

Isaac Newton (1642, 1727) brilliantly wrote about in his book “Opticks“, first published in 1704: “And if at any time I speak of light and rays as coloured or endowed with colours, I would be understood to speak not philosophically and properly, but grossly, and accordingly to such conceptions as vulgar people in seeing all these experiments would be apt to frame. For the rays to speak properly are not coloured. In them there is nothing else then a certain power and disposition to stir up a sensation of this or that colour.”

Later, W. D. Wright was inspired by Newton’s words and published a book named “The Rays are not Coloured” in 1967, stating that “our perception of colour are within us and colours cannot exist unless there is an observer to perceive them. Colour does not exist even in the chain of events between the retinal receptors and the visual cortex, but only when information is finally interpreted in the consciousness of the observer.” – by W. D. Wright, Imperial College of Science and Technology, London

First published by Adam Hilger LTD, London - 1967

First published by Adam Hilger LTD, London – 1967

Therefore, if you go to this museum eager for your kids to learn science, it is better to readjust your expectations. It can be fun but not educational. Most of time you will not find an employee or a volunteer to answer your question, and if you find them it does not mean that they will give you the right answer.

Their uniforms are very misleading. They have two types: employees that are not scientists 99% of the time wear an uniform that says “Scientist”, and volunteers wear an uniform that says “Volunteer” that, although are often retiree from many different areas not related to science, you will have better chances to find a science student among them.

More alarming and very scary is the fact that they offer a “Teacher Workshop” and “Center for the Advancement of Science Education”. According to their own words, the “Teacher Workshop is designed to increase your knowledge of science, improve teaching skills and demonstrate how to use Museum programs and exhibits to enhance science curriculum.” The “Center for the Advancement of Science Education” offers an enormous list of activities like Field Trips, Science Minors, Learning Lab, etc. It would be fantastic if the museum was taking science seriously and updated but this is definitely not the case.

OBS: Before writing this review, I have contacted the museum requesting that the panel with the color definition should be fixed. The answer was NO and the explanation was once more a proof that the MSI Chicago does not have scientists enough and/or no respect for Science.

Color is in the Brain

How to Read a Scientific Paper

How to Read a Scientific Paper

When reading a Science Paper, we have to focus on identifying some basic informations. Therefore, we have to first understand how to identify each of them:

Background: Every paper presents the scenario in the previous literature that left a door open, leading to the present study. Usually, the authors start talking about it in order to address their own question.

Question: What is the question that authors designed the study to answer? Usually, it is presented right after presenting the previous literature.

Logic: What is the rationale of the experiment? In other words, why does it make sense to do the experiment in the way it was done?

Method: First thing to do is to identify the name of the Method. If you don’t know anything about the Method, you should google it before reading more about the Method… and identify:

  • Stimulus: what was presented to the subject
  • Task: what was the subject asked to do
  • Independent variable (IV): the variable that affects the DV (*)
  • Dependent variable (DV): the variable being measured; what is varying in the experiment that is affected by IV or correlated to the IV(*).

It is worth noting that most of the time the IV and DV are included in the paper title.

Results: What are the results of the experiment? Usually, they present many results but always emphasizing the result that is the most important. The results are very specific, and most of the times expressed in numbers, percentages, and statistical results. If you don’t know how to interpret them, skip to the conclusion… but keep in mind that is necessary to understand statistics in order to evaluate the liability of the paper.

Conclusion: How do the authors interpret the results?  What conclusion do they make from them?

(*) More about IV and DV: http://nces.ed.gov/nceskids/help/user_guide/graph/variables.asp

Perceptual Constancy and Audrey Heller’s Photography


Perceptual constancy is an important aspect of our interaction with the world. The size constancy is the easiest one to understand. For example, two telephone poles look the same size when the first is viewed from 100 meters and when the second is viewed from 1 meter, even though the visual angle is very different. A person who appears to be 6 feet tall when he is nearby also appears to be 6 feet tall when he is standing across the room. Now, think of a penny… and you will understand the shape constancy in which the penny looks round both when viewed head on and when viewed from an acute angle. The color constancy is a little more difficult to grasp… think of the color of your car, for example… if you don’t have one, think of the one you are always taking a ride… you always perceive the color of the car as uniform, even under different light sources (sunlight, artificial light, shade). These are few examples of perceptual constancy that are essential to make our lives more stable, letting us freer to worry about other types of non-constancies (Goldstein, 2011; Cohen, forthcoming).

Here are some photos by Audrey Heller that plays with the phenomenon of size constancy:

Eternal Sunshine of the Spotless Mind


Would you erase me from your life and memory?

The movie “Eternal Sunshine Of The Spotless Mind” underlies the scientific discussion about whether our mind is governed by localized or distributed activity in the brain. Is the neural orchestra of our mental functions localized or distributed throughout the brain? The movie starts with the localized theory that is represented by the Lacuna Inc., the company that offers the service of erasing all memories related to one’s person… A non-traditional and impulsive girl (Clementine, Kate Winslet) erases her boyfriend (Joel, Jim Carrey) from her mind with all the memories related to him. Then, Joel figures out what Clementine had just done, and hires Lacuna Inc. to do the same procedure with his memories of Clementine… but during his procedure, he changes his mind, trying to stop it but it was too late, and the company succeeds on erasing Clementine and all memories related to her. The movie then approaches the distributed theory of brain activity when Joel changes his regular routine in an unconsciousness act driven by the familiarity of the name Montauk, a special place for their erased relationship… and they meet each other for the first time (if we consider that they can’t recall the fact that they were in love before). This brilliant fiction written by Charlie Kaufman present us the both models of the relation between mind activity and brain activity that have been conciliated in the study of cognition with the help of Neuroimaging techniques, suggesting that the integrity of our mental functions is at the same time specified and distributed throughout the brain.

Note Clementine’s hair-color and her emotional state.

Vision with Cell Transplant in the Retina [Visão com Transplante de Célula na Retina]


It was published in Nature April 18 2012, a study that suggests that transplanting photoreceptors – nerve cells that line the back of the eye sensitive to light – could form the basis of a new treatment to restore sight in people with retinal degenerative diseases. Loss of photoreceptors is the cause of blindness in many human eye diseases including age-related macular degeneration and retinitis pigmentosa.

Scientists injected cells from young healthy mice directly into the retinas of adult mice that lacked function for this type of photoreceptors. After 6 weeks, the transplanted cells appeared to be functioning almost as well as normal cells and had formed the connections needed to transmit information to the brain. For the first time, transplanted photoreceptor cells were integrate successfully with the existing retinal circuitry and truly improve vision. The group is hopeful that soon they will be able to replicate this success with photoreceptors derived from embryonic stem cells and eventually to develop human trials. The findings also pave the way for techniques to repair the central nervous system as it demonstrates the brain’s amazing ability to connect with newly transplanted neurons.

Nature, April 18 2012, Pearson et. al.: Restoration of vision after transplantation of photoreceptors

Example of Retinitis Pigmentosa

Example of Retinitis Pigmentosa

[Foi publicado em 18 de abril de 2012, na Nature, um estudo que sugere que o transplante de fotorreceptores – células nervosas no fundo do olho sensíveis à luz – poderia formar a base de um novo tratamento para restaurar a visão em pessoas com doenças degenerativas da retina. A perda de fotorreceptores é a causa de cegueira em muitas doenças do olho humano, incluindo a degeneração macular e a retinose pigmentar.

Os cientistas injetaram células de jovens ratos saudáveis diretamente nas retinas de ratos adultos que não tinham função para este tipo de fotorreceptores. Após 6 semanas, as células transplantadas pareceram estar funcionando quase tão bem como as células normais e tinham formado as ligações necessárias para transmitir informação para o cérebro. Pela primeira vez, as células fotorreceptoras transplantadas foram integradas com sucesso ao circuito existente na retina e melhoraram a visão. O grupo está esperançoso de que em breve eles serão capazes de replicar esse sucesso com fotorreceptores derivados de células-tronco embrionárias e, eventualmente, desenvolver testes em humanos. Os resultados também abrem o caminho para técnicas de reparação do sistema nervoso central que vem demonstrando a incrível habilidade do cérebro para se conectar com neurônios recém-transplantados.]