Saturday, June 26, 2010

Password

A few days ago, a friend of mine had her GMail account compromised, resulting in much stress for all concerned. This prompted me to change my passwords.

That was three days ago. Since then, I've logged into GMail maybe ten or fifteen times, and every single time I've initially typed the old password. Sometimes, I catch myself and change it before hitting "enter", but usually not. Access denied. Oops. It's getting slightly better, but I think it'll be a good few days before I'm entering the new password as automatically as I did the old one.

It's not hard to see why this kind of thing happens: I'd typed in the old password hundreds, probably thousands, of times over the course of at least a year. It had become completely automatic. That kind of habit takes a long time to learn, so it's no surprise that it takes quite a while to unlearn (though hopefully not quite as long).

Psychologists will recognize the distinction between declarative memory, my concious knowledge of what my new password is, and procedural memory, my ability to unconsciously type it. It's also commonly known as "muscle memory": this is misleading because it's stored in the brain, like all knowledge, but it nicely expresses the feeling that it's your body that has the memory, rather than "you".

Damage to the hippocampus can leave people unable to remember what happened ten minutes ago, but perfectly capable of learning new skills: they just don't remember how they learned them. But you don't have to suffer brain damage to experience procedural knowledge in the absence of declarative recall. I've sometimes found myself unable to remember my password and only reminded myself by going to the login page and successfully typing it. I knew it all along - but only procedurally.

The thing about procedural knowledge is that when it works, you don't notice it's there. So we almost certainly underestimate its contribution to our lives. If you asked me what happens when I log in to GMail, I'd probably say "I type in my username and my password". But maybe it would be more accurate to say: "I go to the login screen, and my brain types my username and password."

Can I take the credit, given that sometimes I - my conciousness - don't even know the password until my brain's helpfully typed it for me? And while in this case I do know it some of the time, much of our procedural knowledge has no declarative equivalent. I can ride a bike, but if you asked me to tell you how I do it, to spell out the complex velocity-weight-momentum calculations that lie behind the adjustments that my muscles constantly make to keep me upright, I'd be stumped.

"I just sit down and pedal." But if I literally did that and nothing more, I'd fall flat on my face. There's a lot more to cycling than that, but I have no idea what it is. So can I ride a bike, or do I just happen to inhabit a brain that can? Isn't saying that I can ride a bike like saying that I can drive just because I have a chauffeur?


Take this train of thought far enough and you reach some disturbing conclusions. Maybe it's not so hard to accept that various skills lie outside the reach of our concious self, but surely the decisions to use those skills are ours alone. Sure, my brain types my username and password for me, but I'm the one who decided to login to GMail - I could have decided to turn the computer off and go for a walk instead. I have Free Will! Like George W. Bush, I'm the Decider. My brain just handles the boring details.

But isn't deciding a skill too? And willing, remembering, thinking, judging, feeling, concluding - I can do all those things, but if I knew how I do them, I'd win the the Nobel Prize in Physiology or Medicine because I'd just have solved the hardest questions of neuroscience. So can I take credit for doing them, or is it my brain?

Ultimately, every concious act must be constructed from unconscious processes; otherwise there would be an infinite regress of conciousness. If the world rested on the back of a giant turtle, what would the turtle stand on? Turtles all the way down?

Link: The Concept of Mind (1949) is a book by the British philosopher Gilbert Ryle, from which I "borrowed" the ideas in this post, and which was probably the one book that most inspired me to study neuroscience.

Password

A few days ago, a friend of mine had her GMail account compromised, resulting in much stress for all concerned. This prompted me to change my passwords.

That was three days ago. Since then, I've logged into GMail maybe ten or fifteen times, and every single time I've initially typed the old password. Sometimes, I catch myself and change it before hitting "enter", but usually not. Access denied. Oops. It's getting slightly better, but I think it'll be a good few days before I'm entering the new password as automatically as I did the old one.

It's not hard to see why this kind of thing happens: I'd typed in the old password hundreds, probably thousands, of times over the course of at least a year. It had become completely automatic. That kind of habit takes a long time to learn, so it's no surprise that it takes quite a while to unlearn (though hopefully not quite as long).

Psychologists will recognize the distinction between declarative memory, my concious knowledge of what my new password is, and procedural memory, my ability to unconsciously type it. It's also commonly known as "muscle memory": this is misleading because it's stored in the brain, like all knowledge, but it nicely expresses the feeling that it's your body that has the memory, rather than "you".

Damage to the hippocampus can leave people unable to remember what happened ten minutes ago, but perfectly capable of learning new skills: they just don't remember how they learned them. But you don't have to suffer brain damage to experience procedural knowledge in the absence of declarative recall. I've sometimes found myself unable to remember my password and only reminded myself by going to the login page and successfully typing it. I knew it all along - but only procedurally.

The thing about procedural knowledge is that when it works, you don't notice it's there. So we almost certainly underestimate its contribution to our lives. If you asked me what happens when I log in to GMail, I'd probably say "I type in my username and my password". But maybe it would be more accurate to say: "I go to the login screen, and my brain types my username and password."

Can I take the credit, given that sometimes I - my conciousness - don't even know the password until my brain's helpfully typed it for me? And while in this case I do know it some of the time, much of our procedural knowledge has no declarative equivalent. I can ride a bike, but if you asked me to tell you how I do it, to spell out the complex velocity-weight-momentum calculations that lie behind the adjustments that my muscles constantly make to keep me upright, I'd be stumped.

"I just sit down and pedal." But if I literally did that and nothing more, I'd fall flat on my face. There's a lot more to cycling than that, but I have no idea what it is. So can I ride a bike, or do I just happen to inhabit a brain that can? Isn't saying that I can ride a bike like saying that I can drive just because I have a chauffeur?


Take this train of thought far enough and you reach some disturbing conclusions. Maybe it's not so hard to accept that various skills lie outside the reach of our concious self, but surely the decisions to use those skills are ours alone. Sure, my brain types my username and password for me, but I'm the one who decided to login to GMail - I could have decided to turn the computer off and go for a walk instead. I have Free Will! Like George W. Bush, I'm the Decider. My brain just handles the boring details.

But isn't deciding a skill too? And willing, remembering, thinking, judging, feeling, concluding - I can do all those things, but if I knew how I do them, I'd win the the Nobel Prize in Physiology or Medicine because I'd just have solved the hardest questions of neuroscience. So can I take credit for doing them, or is it my brain?

Ultimately, every concious act must be constructed from unconscious processes; otherwise there would be an infinite regress of conciousness. If the world rested on the back of a giant turtle, what would the turtle stand on? Turtles all the way down?

Link: The Concept of Mind (1949) is a book by the British philosopher Gilbert Ryle, from which I "borrowed" the ideas in this post, and which was probably the one book that most inspired me to study neuroscience.

BOM FINAL DE SEMANA A TODOS!!

AS VEZES PRECISAMOS REPENSAR ALGUMAS COISAS. A VIDA NOS MOSTRA MUITAS POSSIBILIDADES.. VEJA A GRANDEZA DESTE FILME!



FINAL DE SEMNA CHEGANDO...FICAMOS ASSIM...COM VONTADE DE DORMIR UM POUQUINHO MAIS!!!!!!!MERECEMOS, NÃO É MESMO!!!!!!!!





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Friday, June 25, 2010

COPA BRASIL- EMPATE!!!!


Hino à Pátria
Recados para Orkut de Brasil

A Pátria não é ninguém: são todos.
E cada qual tem no seio dela o mesmo direito à idéia, à palavra, à associação.
A Pátria não é um sistema, nem uma seita, nem um monopólio, nem uma forma de governo;
é o céu, o solo, o povo, a tradição,
a consciência,
o lar, o berço dos filhos e o
mulo dos antepassados, a comunhão da lei, da língua e da liberdade.
Os que a servem são os que não invejam, os que não infamam, os que não conspiram, os que não desalentam, os que não emudecem, os que não se acobardam, mas resistem, mas se esforçam, mas pacificam, mas discutem, mas praticam a justiça, a admiração, o entusiasmo.
(Rui Barbosa)

PORTUGAL E BRASIL- UNIDOS PELA NOSSA AMIZADE.
UM MUNDO VIRTUAL MUITO ESPECIAL.
UM FRONTEIRA DE AMIGOS.
DOIS CORAÇÕES A PULSAR!!!!

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O BRASIL PODERIA TER FEITO MUITO MAIS. VACILOU MUITO. MAS, ESTAMOS AI..
NEM TUDO ACONTECE COMO SE ESPERA. INFELIZMENTE.
VIVA BRASIL!!!!!VIVA PORTUGAL!!!!!
ESTAMOS AI, CLASSIFICADOS...ISSO É MUITO BOM!!!!!


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The A Team Sets fMRI to Rights

Remember the voodoo correlations and double-dipping controversies that rocked the world of fMRI last year? Well, the guys responsible have teamed up and written a new paper together. They are...

The paper is Everything you never wanted to know about circular analysis, but were afraid to ask. Our all-star team of voodoo-hunters - including Ed "Hannibal" Vul (now styled Professor Vul), Nikolaus "Howling Mad" Kriegeskorte, and Russell "B. A." Poldrack - provide a good overview of the various issues and offer their opinions on how the field should move forward.

The fuss concerns a statistical trap that it's easy for neuroimaging researchers, and certain other scientists, to fall into. Suppose you have a large set of data - like a scan of the brain, which is a set of perhaps 40,000 little cubes called voxels - and you search it for data points where there is a statistically significant effect of some kind.

Because you're searching in so many places, in order to avoid getting lots of false positives you set the threshold for significance very high. That's fine in itself, but a problem arises if you find some significant effects and then take those significant data points and use them as a measure of the size of the effects - because you have specifically selected your data points on the basis that they show the very biggest effects out of all your data. This is called the non-independence error and it can make small effects seem much bigger.

The latest paper offers little that's new in terms of theory, but it's a good read and it's interesting to get the authors' expert opinion on some hot topics. Here's what they have to say about the question of whether it's acceptable to present results that suffer from the non-independence error just to "illustrate" your statistically valid findings:
Q: Are visualizations of non-independent data helpful to illustrate the claims of a paper?

A: Although helpful for exploration and story telling, circular data plots are misleading when presented as though they constitute empirical evidence unaffected by selection. Disclaimers and graphical indications of circularity should accompany such visualizations.
Now an awful lot of people - and I confess that I've been among them - do this without the appropriate disclaimers. Indeed, it is routine. Why? Because it can be useful illustration - although the size of the effects appears to be inflated in such graphs, on a qualitative level they provide a useful impression of the direction and nature of the effects.

But the A Team are right. Such figures are misleading - they mislead about the size of the effect, even if only inadvertently. We should use disclaimers, or ideally, avoid using misleading graphs. Of course, this is a self-appointed committee: no-one has to listen to them. We really should though, because what they're saying is common sense once you understand the issues.

It's really not that scary - as I said on this blog at the outset, this is not going to bring the whole of fMRI crashing down and end everyone's careers; it's a technical issue, but it is a serious one, and we have no excuse for not dealing with it.

ResearchBlogging.orgKriegeskorte, N., Lindquist, M., Nichols, T., Poldrack, R., & Vul, E. (2010). Everything you never wanted to know about circular analysis, but were afraid to ask Journal of Cerebral Blood Flow & Metabolism DOI: 10.1038/jcbfm.2010.86

The A Team Sets fMRI to Rights

Remember the voodoo correlations and double-dipping controversies that rocked the world of fMRI last year? Well, the guys responsible have teamed up and written a new paper together. They are...

The paper is Everything you never wanted to know about circular analysis, but were afraid to ask. Our all-star team of voodoo-hunters - including Ed "Hannibal" Vul (now styled Professor Vul), Nikolaus "Howling Mad" Kriegeskorte, and Russell "B. A." Poldrack - provide a good overview of the various issues and offer their opinions on how the field should move forward.

The fuss concerns a statistical trap that it's easy for neuroimaging researchers, and certain other scientists, to fall into. Suppose you have a large set of data - like a scan of the brain, which is a set of perhaps 40,000 little cubes called voxels - and you search it for data points where there is a statistically significant effect of some kind.

Because you're searching in so many places, in order to avoid getting lots of false positives you set the threshold for significance very high. That's fine in itself, but a problem arises if you find some significant effects and then take those significant data points and use them as a measure of the size of the effects - because you have specifically selected your data points on the basis that they show the very biggest effects out of all your data. This is called the non-independence error and it can make small effects seem much bigger.

The latest paper offers little that's new in terms of theory, but it's a good read and it's interesting to get the authors' expert opinion on some hot topics. Here's what they have to say about the question of whether it's acceptable to present results that suffer from the non-independence error just to "illustrate" your statistically valid findings:
Q: Are visualizations of non-independent data helpful to illustrate the claims of a paper?

A: Although helpful for exploration and story telling, circular data plots are misleading when presented as though they constitute empirical evidence unaffected by selection. Disclaimers and graphical indications of circularity should accompany such visualizations.
Now an awful lot of people - and I confess that I've been among them - do this without the appropriate disclaimers. Indeed, it is routine. Why? Because it can be useful illustration - although the size of the effects appears to be inflated in such graphs, on a qualitative level they provide a useful impression of the direction and nature of the effects.

But the A Team are right. Such figures are misleading - they mislead about the size of the effect, even if only inadvertently. We should use disclaimers, or ideally, avoid using misleading graphs. Of course, this is a self-appointed committee: no-one has to listen to them. We really should though, because what they're saying is common sense once you understand the issues.

It's really not that scary - as I said on this blog at the outset, this is not going to bring the whole of fMRI crashing down and end everyone's careers; it's a technical issue, but it is a serious one, and we have no excuse for not dealing with it.

ResearchBlogging.orgKriegeskorte, N., Lindquist, M., Nichols, T., Poldrack, R., & Vul, E. (2010). Everything you never wanted to know about circular analysis, but were afraid to ask Journal of Cerebral Blood Flow & Metabolism DOI: 10.1038/jcbfm.2010.86

Thursday, June 24, 2010

BRASIL X PORTUGAL

ESTE DIA VAI DAR O QUE COMENTAR!!!!!!
25 DE JUNHO DE 2010!!!!!!


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MEUS AMIGOS DE PORTUGAL VAMOS ESTAR TODOS UNIDOS TORCENDO...
QUE VENÇA O MELHOR...
NOSSA AMIZADE JÁ VENCEU!!!!!
SÍMBOLO NACIONAL

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AQUI TODOS SE UNEM PELA GRANDE AMIZADE.
UMA NAÇÃO TODA ESTÁ UNIDA PARA TORCER.
VIVA A TODOS NÓS!!!!




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