Σάββατο 13 Φεβρουαρίου 2010

Η τιτανομαχία και τα παρατράγουδα της είναι Ελληνική παράδοση

Η τιτανομαχία περιγράφει τις σχέσεις των μελών της πρώτης ελληνικής οικογένειας και οι Θεοί αγαπούνε και ερωτεύονται κάθε άνθρωπο (εκτός των αδελφών, γονέων, παιδιών).

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Τετάρτη 10 Φεβρουαρίου 2010

Education: Learning Styles Debunked

Web address:
http://www.sciencedaily.com/releases/2009/12/
091216162356.htm

Education: Learning Styles Debunked

ScienceDaily (Dec. 17, 2009) — Are you a verbal learner or a visual learner? Chances are, you've pegged yourself or your children as either one or the other and rely on study techniques that suit your individual learning needs. And you're not alone -- for more than 30 years, the notion that teaching methods should match a student's particular learning style has exerted a powerful influence on education. The long-standing popularity of the learning styles movement has in turn created a thriving commercial market amongst researchers, educators, and the general public.

The wide appeal of the idea that some students will learn better when material is presented visually and that others will learn better when the material is presented verbally, or even in some other way, is evident in the vast number of learning-style tests and teaching guides available for purchase and used in schools. But does scientific research really support the existence of different learning styles, or the hypothesis that people learn better when taught in a way that matches their own unique style?

Unfortunately, the answer is no, according to a major new report published this month in Psychological Science in the Public Interest, a journal of the Association for Psychological Science. The report, authored by a team of eminent researchers in the psychology of learning -- Hal Pashler (University of San Diego), Mark McDaniel (Washington University in St. Louis), Doug Rohrer (University of South Florida), and Robert Bjork (University of California, Los Angeles) -- reviews the existing literature on learning styles and finds that although numerous studies have purported to show the existence of different kinds of learners (such as "auditory learners" and "visual learners"), those studies have not used the type of randomized research designs that would make their findings credible.

Nearly all of the studies that purport to provide evidence for learning styles fail to satisfy key criteria for scientific validity. Any experiment designed to test the learning-styles hypothesis would need to classify learners into categories and then randomly assign the learners to use one of several different learning methods, and the participants would need to take the same test at the end of the experiment. If there is truth to the idea that learning styles and teaching styles should mesh, then learners with a given style, say visual-spatial, should learn better with instruction that meshes with that style. The authors found that of the very large number of studies claiming to support the learning-styles hypothesis, very few used this type of research design. Of those that did, some provided evidence flatly contradictory to this meshing hypothesis, and the few findings in line with the meshing idea did not assess popular learning-style schemes.

No less than 71 different models of learning styles have been proposed over the years. Most have no doubt been created with students' best interests in mind, and to create more suitable environments for learning. But psychological research has not found that people learn differently, at least not in the ways learning-styles proponents claim. Given the lack of scientific evidence, the authors argue that the currently widespread use of learning-style tests and teaching tools is a wasteful use of limited educational resources.

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Adapted from materials provided by Association for Psychological Science, via EurekAlert!, a service of AAAS.

Journal References:

Rohrer et al. Increasing Retention Without Increasing Study Time. Current Directions in Psychological Science, 2007; 16 (4): 183 DOI: 10.1111/j.1467-8721.2007.00500.x
McDaniel et al. The Read-Recite-Review Study Strategy: Effective and Portable. Psychological Science, 2009; 20 (4): 516 DOI: 10.1111/j.1467-9280.2009.02325.x
Roediger et al. Test-Enhanced Learning. Taking Memory Tests Improves Long-Term Retention. Psychological Science, 2006; 17 (3): 249 DOI: 10.1111/j.1467-9280.2006.01693.x
Hal Pashler et al. Learning Styles: Concepts and Evidence. Psychological Science in the Public Interest, (in press)

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Different Parts Of The Brain Handle Fantasy And Reality

Web address:
http://www.sciencedaily.com/releases/2002/03/
020329072629.htm

Different Parts Of The Brain Handle Fantasy And Reality

ScienceDaily (Apr. 1, 2002) — The ability to recognize objects in the real world is handled by different parts of the brain than those that allow us to imagine what the world is like. That is the result of a brain mapping experiment published in the March 28 issue of the journal Neuron. The study focused on two cognitive tasks widely used by experimental psychologists. One is mental rotation – mentally rotating a complex object into a different position to compare it with a second similar shape – and object recognition – determining whether two complex objects are the same or different.

"Mental rotation and object recognition are indistinguishable from a behavioral viewpoint: You can't tell them apart," says the paper's first author, Isabel Gauthier, assistant professor of psychology at Vanderbilt. "As a result, the field has been deadlocked over the question of whether the brain uses the same mechanism or different mechanisms for the two tasks."
Michael J. Tarr, one of the paper's co-authors and professor of cognitive and linguistic sciences at Brown University, had proposed in several papers with Steven Pinker at the Massachusetts Institute of Technology that the same mechanism must be involved in the two tasks. "There are parts of our brain that are involved in our ability to imagine the world," he says. "The question is, 'Are those the same as the parts of the brain that we use to know what things are?' And the answer appears to be, 'No, they are not.'"
Also collaborating on the study were William G. Hayward of Chinese University of Hong Kong and an fMRI team from the Yale School of Medicine headed by John C. Gore.
To find out what parts of the brain are involved in these two mental tasks, the researchers began with six unfamiliar geometric shapes that look something like the pieces from an unfolded Rubic's cube. They used three of these objects – two of which were mirror images – for the mental rotation tasks and three which were slightly different but similar in appearance for the object recognition tasks. Next, they assembled a group of 15 subjects and used functional Magnetic Resonance Imaging machine to measure activity levels in different parts of their brains.
During the fMRI sessions, the researchers had the subjects perform two types of tasks using the objects. They displayed the objects in pairs on a screen and, in one case, they asked the subjects whether the two are identical or mirror images – a basic mental rotation task. In the other case, they asked them whether the two objects were the same or different – a basic object recognition task. The objects were shown at different angles from each other on the horizontal, vertical and out-of-plane axes and the researchers measured the time it took the people to answer.
When they examined the brain scans, the scientists found that the areas activated during the two tasks tended to lie on two different pathways in the visual system. These two pathways, called the ventral and dorsal, are sometimes called the "what" and "where" pathways. When asked questions about the identity of an object – for example, is it the same shape as a second object? – then the ventral pathway, which includes the temporal lobe, is activated. But when a person is asked where an object is located, the dorsal pathway, which lies in the parietal lobe, becomes active.
The first place the researchers looked was the parietal lobe because previous studies had shown that it is involved in mental rotation tasks. They confirmed these observations and found that when the difference in orientation in the mental rotation tasks was large, the amount of parietal lobe activity was greater than when the difference was small.
In the object recognition tasks, however, the researchers saw a much different pattern. They did see some activity in the parietal region. Surprisingly, however, the amount of activity in the parietal lobe decreased at larger orientation differences. In addition, they found that the brain area that did show an increase in activity with larger differences in orientation was in the ventral pathway. "This is the first indication we have that the brain doesn't rely on the same processes to accomplish these two tasks, despite the fact that they appear to be so similar," says Gauthier.
During the course of evolution, it seems as if the same solutions have arisen more than once for similar problems in the way our brains work, adds Tarr. "They look very similar behaviorally, but it turns out they use completely different neural circuits and the brain doesn't know how to put them together."
For more news about research at Vanderbilt, visit the online research magazine Exploration at http://exploration.vanderbilt.edu.

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Adapted from materials provided by Vanderbilt University.

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Magnesium Supplement Helps Boost Brainpower

Web address:
http://www.sciencedaily.com/releases/2010/01/
100127121524.htm

Magnesium Supplement Helps Boost Brainpower

Increasing magnesium intake may be a valid strategy to enhance cognitive abilities. (Credit: iStockphoto/Vasiliy Yakobchuk)

ScienceDaily (Feb. 2, 2010) — New research finds that an increase in brain magnesium improves learning and memory in young and old rats. The study, published in the January 28th issue of the journal Neuron, suggests that increasing magnesium intake may be a valid strategy to enhance cognitive abilities and supports speculation that inadequate levels of magnesium impair cognitive function, leading to faster deterioration of memory in aging humans.

Diet can have a significant impact on cognitive capacity. Identification of dietary factors which have a positive influence on synapses, the sites of communication between neurons, might help to enhance learning and memory and prevent their decline with age and disease. Professor Guosong Liu, Director of the Center for Learning and Memory at Tsinghua University in Beijing, China, led a study examining whether increased levels of one such dietary supplement, magnesium, boosts brain power.
"Magnesium is essential for the proper functioning of many tissues in the body, including the brain and, in an earlier study, we demonstrated that magnesium promoted synaptic plasticity in cultured brain cells," explains Dr. Liu. "Therefore it was tempting to take our studies a step further and investigate whether an increase in brain magnesium levels enhanced cognitive function in animals."
Because it is difficult to boost brain magnesium levels with traditional oral supplements, Dr. Liu and colleagues developed a new magnesium compound, magnesium-L-threonate (MgT) that could significantly increase magnesium in the brain via dietary supplementation. They used MgT to increase magnesium in rats of different ages and then looked for behavioral and cellular changes associated with memory.
"We found that increased brain magnesium enhanced many different forms of learning and memory in both young and aged rats," says Dr. Liu. A close examination of cellular changes associated with memory revealed an increase in the number of functional synapses, activation of key signaling molecules and an enhancement of short- and long-term synaptic processes that are crucial for learning and memory.
The authors note that the control rats in this study had a normal diet which is widely accepted to contain a sufficient amount of magnesium, and that the observed effects were due to elevation of magnesium to levels higher than provided by a normal diet.
"Our findings suggest that elevating brain magnesium content via increasing magnesium intake might be a useful new strategy to enhance cognitive abilities," explains Dr. Liu. "Moreover, half the population of industrialized countries has a magnesium deficit, which increases with aging. This may very well contribute to age-dependent memory decline; increasing magnesium intake might prevent or reduce such decline."

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Adapted from materials provided by Cell Press, via EurekAlert!, a service of AAAS.

Journal Reference:

Inna Slutsky, Nashat Abumaria, Long-Jun Wu, Chao Huang, Ling Zhang, Bo Li, Xiang Zhao, Arvind Govindarajan, Ming-Gao Zhao, Min Zhuo, Susumu Tonegawa and Guosong Liu. Enhancement of Learning and Memory by Elevating Brain Magnesium. Neuron, Jan. 28, 2010

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