[I found this little mini-essay lying around. It's thematic with some of the older posts I had stuck here, so I thought I'd save it here too. Plus it's vaguely related to some of my current thinking about skill learning in cognitive training.]
A link took me to this post on a college teacher who's fed up with teaching and going to quit. I think it actually reflects a fairly common "teaching mid-life crisis" that hits a lot of professors in their 40's. But I jotted down some of my thoughts following his rant.
http://www.insidehighered.com/views/2008/10/31/smith
My sense is that JS's core problem is that he's become too entrenched in the minutia of teaching -- grading students for following the rules, turning things in on time, following the social norms he tries to lay out in class.
As a teacher, I think you need to periodically re-ask yourself, "what should the students be learning in class?"
Lately, I've become quite curious about the increasing amount of high-quality information you can get through Wikipedia or Google on the internet. If you can look up any fact nearly instantaneously via your phone, what facts do you need to memorize in college? Maybe just things that gain value by being recalled faster than you can type the search word into Google (things like jargon in the field you hope to work in -- you can't really have a conversation when you have to look up a lot of vocabulary terms).
So what else do students learn in college? Skills is one thing. How to think critically, evaluate evidence, come up with alternate hypothesis, creative solutions. Also how to communicate and present ideas convincingly. I don't think you can look up skills on Google.
I also think students also learn a bit more about the world, who they are and how they're going to live their lives afterwards. And I think the social networking probably has a bigger practical impact on everything that happens afterwards in life than anything (or everything) they actually learn from classes. I'm not sure I can affect social-networking much in typical classes, but it awareness of it's value makes my less critical of the consequences of socializing (e.g., if a student produces a lame assignment because socializing interfered with effort, it's not entirely clear to me that they have always made a bad decision).
So I try to teach skills and a few facts and I try to be reasonably entertaining. I have another pet idea that at a basic level, information = entertainment. I think if you're really learning something, it's going to generally be entertaining (somehow the 'entertainment' element arises from integrating acquired knowledge into existing knowledge -- I think). The students are paying a lot to be here and even though a lot of what they're paying for is the environment around the classes (self-discovery, social networking), it seems like making the classes enjoyable makes it more fun for all of us.
I don't really care about the entitled attitudes that lead them to negotiate constantly for higher grades. I never give in, but only to avoid penalizing the students who don't argue. Although, you could probably make a case that arguing on your own behalf is one of the more important skills to learn in college. I do echo JS's "I don't give grades, you earn them" idea. I point out their goal is to learn and I try to assess the quality of their learning via the exams & papers. If the assessment is fair, the assessment is fair. In the end, though, I don't really care that much about grades. They are mostly an effort indicator -- if you are willing to work hard, you can have your A. And if they all work hard, I think that's ok.
I suppose if there are students who are intellectually incapable of mastering the material even when they work hard, I'm supposed to mark them as such with lower grades to warn off professional schools and employers. It appears to correlate with effort most of the time, though.
OTOH, I don't teach as much as JS probably does. And I happen to teach only small classes (10-30). Teaching skills in a class of 300 is probably hard.
Wednesday, February 17, 2010
Friday, February 12, 2010
Mental weightlifting
"Of course it works. Didn't you ever do pushups before heading out to the beach?" I was listening to a well-known cognitive neuroscientist and fMRI guru explaining the close relationship between neuronal activity and blood flow that is the basic of functional neuroimaging of the brain. He wasn't talking to me, I was helping to explain the technique but I didn't get his example right away, so I had to inquire, "um, what?" He explained that pushups caused more blood to flow to the muscles of your arms, beefing them up and enhancing one's physique in anticipation of attracting hotties on the beach.
"Oh, well ok, then." Unlike this particular quite famous cognitive neuroscientist, I don't think my physique was ever within any reasonable number of pushups from attracting any positive attention at the beach. It's still a memorable example, though, and it certainly works in brain imaging: neurons doing "pushups" (e.g., firing electrical potentials) draw additional blood to active areas and blood flow changes can be picked up in MRI scanners to track changes in neural activity.
But how far can we push the analogy? Can we build up and strengthen our neural functions by targeted programs of mental exercise? Practically, of course the answer is "yes." If we study chess, mathematics, music, or physical skills like sports we get better at them. That means we're learning and learning means there are physical changes in our brains reflecting this. But can we bulk up mentally?
If you accepted the idea that we don't grow new neurons as adults, you'd be inclined to say "no." You might even be tempted to make a disparaging remark about the thoroughly discredited 19th-century study of phrenology. Phrenology is a famous example of pseudo-science based on trying to assess mental abilities by measuring bumps on your head. The shred of scientific idea behind it was that your relatively more effective mental functions were bigger and this would show up as larger bulges in your skull. That turns out to be as silly as it sounds, but there's an important idea hiding in it, namely that cognitive functions in the brain are physically localized. That turns out to be true in many cases and was not well appreciated until much later.
It also turns out that we do grow new neurons in the brain. Rusty Gage and colleagues and subsequently many other neuroscientists have studied adult neurogenesis and found there is some addition of new neurons in the adult brain. And even better, it can be enhanced by rich environments with lots of mental stimulation. Most of that basic neuroscience is examined in animals, but Eleanor Maguire has reported some intriguing results about changes in the size of specific brain structures in London cabbies. That sounds odd, but London is a particularly difficult city to navigate within and Dr. Maguire has observed that cabbies with many years of experience appear to have relative increases in the size of a brain region associated with spatial memory. Don't chalk this one up as a vindication for phrenology, though, the region of the brain increasing in size is essentially in the part of the cortex furthest from the skull. You need an MRI to see it, not just looking for bumps on the skull.
There have been other reports of systematic differences in the size of specific brain regions like auditory cortex for musicians. Those results quickly lead one back to a nature/nuture style debate. Did the brain differences occur based largely on genes and lead those people to become musicians? Or did the differences in size occur due to extensive music practice?
An intriguing result along these lines was recently reported by Erickson and colleagues about learning rates in videogame play. Larger volume in the dorsal part of the striatum (a central and subcortical brain region) predicted faster learning of Space Fortress, a fairly simple video game. The nature/nurture question is intriguing here, too. Were the fast learners genetically advantaged by a larger part of the brain involved in learning this game? Or had they developed that part of the brain as a muscle by extensive prior experience with games?
Either account is very interesting (and they aren't mutually exclusive), but the brain-as-muscle possibility is particularly compelling. If we can strengthen the brain as a muscle, we have even more reason to believe in the "use it or lose it" hypothesis of mental activity being effective to hold off cognitive decline associated with aging. There's a decent accumulation of evidence that mentally active people age well, but it's also the case that aging well lets you stay mentally active.
Intervention studies have been fairly promising. A huge, multi-center study of more than 2k older adults found that providing just 10 hours of training in memory, attention or decision making produced gains and the gains lasted 5 years. On the downside, training in one area didn't help the other two abilities. Nor was there any evidence of slower overall decline, so "using it" may not generally prevent you from still "losing it." It might give you more to lose, so to speak, so you function better for longer.
So those "brain training" sites on the internet that offer to provide some mental weightlifting might actually be helpful. And you might not just have to work out like in a gym, another recent report by Chandramallika Basak (working with Arthur Kramer of Univ Illinois, who was also a contributor to the Erickson report above) found that "training" by playing Rise of Nations for 20 hours led to improvements in "executive control functions" like decision making, working memory and task switching in a group of older participants. Notably, those cognitive functions tend to be at least partly supported by the same region that was larger in the better Space Fortress learners.
So maybe you can grow your brain by mental weightlifting. And maybe you can even do mental weightlifting with video games. That'd be cool.
[Self-editing note: this essay doesn't have the cites or links to the background research, although they are all pretty easy to find on google scholar. Nor is it really written in a tight, accessible style you'd like to see in a media-oriented article on science. It seems natural to write in a semi-formal rambling style, but I wonder if it's useful.]
"Oh, well ok, then." Unlike this particular quite famous cognitive neuroscientist, I don't think my physique was ever within any reasonable number of pushups from attracting any positive attention at the beach. It's still a memorable example, though, and it certainly works in brain imaging: neurons doing "pushups" (e.g., firing electrical potentials) draw additional blood to active areas and blood flow changes can be picked up in MRI scanners to track changes in neural activity.
But how far can we push the analogy? Can we build up and strengthen our neural functions by targeted programs of mental exercise? Practically, of course the answer is "yes." If we study chess, mathematics, music, or physical skills like sports we get better at them. That means we're learning and learning means there are physical changes in our brains reflecting this. But can we bulk up mentally?
If you accepted the idea that we don't grow new neurons as adults, you'd be inclined to say "no." You might even be tempted to make a disparaging remark about the thoroughly discredited 19th-century study of phrenology. Phrenology is a famous example of pseudo-science based on trying to assess mental abilities by measuring bumps on your head. The shred of scientific idea behind it was that your relatively more effective mental functions were bigger and this would show up as larger bulges in your skull. That turns out to be as silly as it sounds, but there's an important idea hiding in it, namely that cognitive functions in the brain are physically localized. That turns out to be true in many cases and was not well appreciated until much later.
It also turns out that we do grow new neurons in the brain. Rusty Gage and colleagues and subsequently many other neuroscientists have studied adult neurogenesis and found there is some addition of new neurons in the adult brain. And even better, it can be enhanced by rich environments with lots of mental stimulation. Most of that basic neuroscience is examined in animals, but Eleanor Maguire has reported some intriguing results about changes in the size of specific brain structures in London cabbies. That sounds odd, but London is a particularly difficult city to navigate within and Dr. Maguire has observed that cabbies with many years of experience appear to have relative increases in the size of a brain region associated with spatial memory. Don't chalk this one up as a vindication for phrenology, though, the region of the brain increasing in size is essentially in the part of the cortex furthest from the skull. You need an MRI to see it, not just looking for bumps on the skull.
There have been other reports of systematic differences in the size of specific brain regions like auditory cortex for musicians. Those results quickly lead one back to a nature/nuture style debate. Did the brain differences occur based largely on genes and lead those people to become musicians? Or did the differences in size occur due to extensive music practice?
An intriguing result along these lines was recently reported by Erickson and colleagues about learning rates in videogame play. Larger volume in the dorsal part of the striatum (a central and subcortical brain region) predicted faster learning of Space Fortress, a fairly simple video game. The nature/nurture question is intriguing here, too. Were the fast learners genetically advantaged by a larger part of the brain involved in learning this game? Or had they developed that part of the brain as a muscle by extensive prior experience with games?
Either account is very interesting (and they aren't mutually exclusive), but the brain-as-muscle possibility is particularly compelling. If we can strengthen the brain as a muscle, we have even more reason to believe in the "use it or lose it" hypothesis of mental activity being effective to hold off cognitive decline associated with aging. There's a decent accumulation of evidence that mentally active people age well, but it's also the case that aging well lets you stay mentally active.
Intervention studies have been fairly promising. A huge, multi-center study of more than 2k older adults found that providing just 10 hours of training in memory, attention or decision making produced gains and the gains lasted 5 years. On the downside, training in one area didn't help the other two abilities. Nor was there any evidence of slower overall decline, so "using it" may not generally prevent you from still "losing it." It might give you more to lose, so to speak, so you function better for longer.
So those "brain training" sites on the internet that offer to provide some mental weightlifting might actually be helpful. And you might not just have to work out like in a gym, another recent report by Chandramallika Basak (working with Arthur Kramer of Univ Illinois, who was also a contributor to the Erickson report above) found that "training" by playing Rise of Nations for 20 hours led to improvements in "executive control functions" like decision making, working memory and task switching in a group of older participants. Notably, those cognitive functions tend to be at least partly supported by the same region that was larger in the better Space Fortress learners.
So maybe you can grow your brain by mental weightlifting. And maybe you can even do mental weightlifting with video games. That'd be cool.
[Self-editing note: this essay doesn't have the cites or links to the background research, although they are all pretty easy to find on google scholar. Nor is it really written in a tight, accessible style you'd like to see in a media-oriented article on science. It seems natural to write in a semi-formal rambling style, but I wonder if it's useful.]
Sunday, August 23, 2009
Cryptography
Why "cortical cryptography"? A fundamental question of Cognitive Neuroscience is the question of how information is represented in the neurons and synapses of the human brain. In cognitive psychology studies of learning and memory, we attempt to identify and control the type of information being acquired and we then observe the behavioral consequences that follow to verify the learning.
What is happening in-between the presentation of controlled information to the participant and the observation of their subsequent responses is essentially the encryption of information into the brain of the participant. So we can say that trying to understand the representation of information in neural systems is analogous to attempting to determine the encryption/decryption algorithm that the brain uses.
In basic research that we've been doing for awhile in the lab, I frequently find myself describing one of the goals of the research as identifying the operating characteristics of specific memory systems that we believe we can isolate. We attempt to find boundary conditions on the rate of learning, the applicability of the information (flexibility), the limitations on complexity of information to be acquired, the effect of passage of time (memory decay, forgetting).
Internally, I think of this as being something like a timing channel attack on this mysterious encryption algorithm.
From Wikipedia, http://en.wikipedia.org/wiki/Timing_attack
We are currently looking at perceptual-motor sequence learning, which we believe is largely supported by cortico-striatal circuit loops (from the basal ganglia to the cortex and back). There are a fair number of neurons in the circuit, but I have this hunch that if we can get some basic characteristics of the learning ability of the system, e.g., the bandwidth of the learning rate, that will rule out some possible encoding algorithms and constrain the set of plausible encryption algorithms.
What is happening in-between the presentation of controlled information to the participant and the observation of their subsequent responses is essentially the encryption of information into the brain of the participant. So we can say that trying to understand the representation of information in neural systems is analogous to attempting to determine the encryption/decryption algorithm that the brain uses.
In basic research that we've been doing for awhile in the lab, I frequently find myself describing one of the goals of the research as identifying the operating characteristics of specific memory systems that we believe we can isolate. We attempt to find boundary conditions on the rate of learning, the applicability of the information (flexibility), the limitations on complexity of information to be acquired, the effect of passage of time (memory decay, forgetting).
Internally, I think of this as being something like a timing channel attack on this mysterious encryption algorithm.
From Wikipedia, http://en.wikipedia.org/wiki/Timing_attack
In cryptography, a timing attack is a side channel attack in which the attacker attempts to compromise a cryptosystem by analyzing the time taken to execute cryptographic algorithms. Every logical operation in a computer takes time to execute, and the time can differ based on the input; with precise measurements of the time for each operation, an attacker can work backwards to the input.I think I'd state the last bit a little differently -- I want to try to work out the characteristics (including time) of the encryption algorithm not to identify the input (we control the input), but to figure out the algorithm itself.
We are currently looking at perceptual-motor sequence learning, which we believe is largely supported by cortico-striatal circuit loops (from the basal ganglia to the cortex and back). There are a fair number of neurons in the circuit, but I have this hunch that if we can get some basic characteristics of the learning ability of the system, e.g., the bandwidth of the learning rate, that will rule out some possible encoding algorithms and constrain the set of plausible encryption algorithms.
Friday, July 24, 2009
Knowing versus Understanding
They aren't the same thing. As a while male, I know racism is wrong and I know constraining a woman's right to choose is wrong. But I cannot truly understand all the implications of these. Two examples from this week:
1. Amanda Marcotte at Pandagon talks briefly about a bill being considered in the Ohio legislature that would require women to get the permission of the sperm donor before getting an abortion. I know immediately this is a horrifying law and also that these types of laws generally do not get passed (except in South Dakota). But in writing about the practicalities, she points out that women will just get a male friend to vouch for being the father and:
2. Ta-Nehisi Coates has been mulling over the Gates' arrest in his own house in Cambridge. And also the death of Shem Walker in NYC. Two black men who were disrespectful to cops, but did nothing obviously wrong. One arrested, the other shot dead. I know being a cop is hard, they are almost always meaning well and I know it's best to always be respectful.
But I do not know what it's like to be a responsible, successful black person (man in particular, I suspect) and have to live one's whole life knowing this could be around the corner for you. One day you are part of the priviledged class -- you're successful, social responsible and doing it right. And the next day you're persecuted for your race. I feel like Dave Chappelle and Wanda Sykes have both done comedy on this theme. I find their routines funny and I feel like I "know" what they're talking about. But when TNC says he doesn't feel good with a cop like that holstering a gun around his kids, I realize I don't really understand.
Not understanding doesn't mean I can't be part of the conversation, nor that my opinion is totally invalid. Or even that I can't be right in an argument over policy even with somebody who really does understand. But as a priviledged white male, I have to remember that I don't really feel it the same way they do and that does matter sometimes.
1. Amanda Marcotte at Pandagon talks briefly about a bill being considered in the Ohio legislature that would require women to get the permission of the sperm donor before getting an abortion. I know immediately this is a horrifying law and also that these types of laws generally do not get passed (except in South Dakota). But in writing about the practicalities, she points out that women will just get a male friend to vouch for being the father and:
Every woman reading this is taking a quick mental inventory of what man they could trust to do this without gloating about his power over you.Yes. She's right and I didn't think of that right away. That's the difference between knowing and understanding. I know the proposed law is wrong, but I don't live with the knowledge that the people around me might democratically vote to take away my basic freedoms at any time, so I don't have this type of reflexive thinking. Althought I'd like to think I'd be the kind of person my female friends would think of as absolutely reliable in this spot. I wonder if they do.
2. Ta-Nehisi Coates has been mulling over the Gates' arrest in his own house in Cambridge. And also the death of Shem Walker in NYC. Two black men who were disrespectful to cops, but did nothing obviously wrong. One arrested, the other shot dead. I know being a cop is hard, they are almost always meaning well and I know it's best to always be respectful.
But I do not know what it's like to be a responsible, successful black person (man in particular, I suspect) and have to live one's whole life knowing this could be around the corner for you. One day you are part of the priviledged class -- you're successful, social responsible and doing it right. And the next day you're persecuted for your race. I feel like Dave Chappelle and Wanda Sykes have both done comedy on this theme. I find their routines funny and I feel like I "know" what they're talking about. But when TNC says he doesn't feel good with a cop like that holstering a gun around his kids, I realize I don't really understand.
Not understanding doesn't mean I can't be part of the conversation, nor that my opinion is totally invalid. Or even that I can't be right in an argument over policy even with somebody who really does understand. But as a priviledged white male, I have to remember that I don't really feel it the same way they do and that does matter sometimes.
Tuesday, July 21, 2009
Nativism, fiction, fantasy and politics.
There are two novels that can change a bookish fourteen-year old's life: The Lord of the Rings and Atlas Shrugged. One is a childish fantasy that often engenders a lifelong obsession with its unbelievable heroes, leading to an emotionally stunted, socially crippled adulthood, unable to deal with the real world. The other, of course, involves orcs.
-- Kung Fu Monkey
A very common theme in fantasy is based around a world where some lucky fraction of the population has an innate ability to control magic. The same concept occurs in SF and comic book worlds with other kinds of special powers (especially mental powers like the Force). Usually the story begins with the protagonist discovering something that indicates that they are special and often then being contacted by a secret or semi-secret society for training and the story's adventures.
It's all fine and fun and the are a million ways to tell the story of growth and self-discovery from there. The meme's popularity suggests there's something pretty fundamental (adolescent?) about the idea of suddenly discovering that you are special and life isn't as ordinary and mundane as it seems.
But hiding under the concept is a very strong theory of nativism -- some people are born special. Those endowed with special powers can do things other cannot. This enables the story to be constructed as: something bad is going to happen and only the protagonist (you) can prevent it! If it didn't require specialness, then anybody could do it.
If the author needs to flesh out the world with other characters who share the specialness, then it will be necessary to figure out how to place the super-powered (magical) in the world. A question to face is then: why don't the super-powered run everything? What stops them from taking over the world and enslaving the non-powered? Often, this is set up as the thing the villian will do with their super-powers and the task of the protagonist is to stop them.
So you seem to find the super-powered ending up in certain kinds of roles. They might be hidden for fear of persecution (e.g., early X-men or Harry Potter) or perhaps they take on hidden, specialized advisory or problem-solving roles (Jedi in Star Wars, wizards in LoTR, most comic books). Some sense of duty or empathy towards the unpowered keeps them from exerting their dominance over everybody else. But it's also worth noting that the fiction worlds based on this idea are virtually never really democratic. At best they are democratic until trouble comes and then control is turned over to the super-powered elite to save everybody.
But even without evidence of magical superpowers, theories of nativist differences among people are everywhere as explanations of real-world phenomena. Given how much inequality exists in society, there's going to be a temptation to hypothesize that some fraction of the reason that some people end up at the high end is based on nativist differences (better IQ genes is the most popular version). Note that this is a lot like saying you're born with superpowers -- superpowers of intellect or related success-increasing traits.
I suspect this idea is what makes Randianism, objectivism and related forms of libertarian thinking so attractive to adolescents (and some never get over it). It's like discovering that you are Harry Potter, only instead of being a particularly powerful wizard, your power is in your ability to generally be on the winning side in our capitalist society. And if you want to push on that idea, well, why shouldn't the best and brightest own and run everything? Do you want imbeciles making policy decisions?
If you accept the logic of strong innate/nativist differences in ability, it's a tough logic to fight. One way is the "smart technocrat" concept, which is a lot like taking the best and brightest and making them the Jedi (wizards) of real society. Perhaps operating as stealthy bureaucrats who quiety solve problems and run things from behind the scenes (e.g., the Fed Reserve Chair).
This seems to map onto political approaches. In general, the Republican version says let competition work itself out and let the best and brightest have what they need to run the world the best. I would guess why they end up being the natural party of racists -- anybody who believes they are genetically superior to others wants the benefit of that superiority.
On the Democratic side, I think there's a number of different approaches to opposing the idea. The empathic "smart technocrat" (i.e., neoliberal) approach is one. A harder approach is to attack the underlying nativism directly.
In a generally laissez-faire society, competition (markets) will spread people out along a success continuum. The more successful will tend to have more resources and frequently as a result also have greater control over the political structure. If you are both strongly nativist and believe that success is well-predicted by innate differences, you should be ok with this since the better, smarter, more innately successful people will tend to be in charge.
But this fails if either innate differences are relatively small or success is strongly affected by non-innate factors (the phenotype does not always follow from the genotype). In either case, there is less reason to believe the set of genes among the successful is any more likely to predict future success than the sets of genes among the unsuccessful. From there, it is easy to argue in favor of democracy and for more equitable distribution of resources.
Wednesday, July 8, 2009
PGG
A recent letter to Nature looking at communal activities and whether/how/if they emerge from individual dynamics clued me in to some of the ideas in current research on this topic.
The model these authors use (and appears to be standard) is the Public Goods Game (PGG). In this, a group of actors each chooses to cooperate at some cost 'c' and the benefit of the cooperation is distributed across the whole group, both cooperators and defectors. Defecting is still the dominant strategy because you gain the benefit without paying the cost. The question is, how do you get a group to cooperate under these conditions?
One idea is that there are 'punishers' who identify and punish the defectors, making defecting no longer a viable strategy. The authors are tackling the question of how you get punishers into a community and come up with some conditions under which the most common stable equilibrium is a mix of cooperators and punishers.
Some points of basic difference in thinking:
* The PGG game is a nice extension to communal activities. And my idea of having enforced social norms seems to imply the existence of some sort of enforcer (punisher). How social norm enforcers get into the system seems more basic than my thinking.
* But it doesn't seem to consider the idea of competing communities. Those would seem to enforce a certain kind of punishment as well. If your community doesn't cooperate and gain the benefits, a neighboring community (tribe) will out-compete you.
* The PGG game also implicitly leaves the D-D cell as a very bad thing. I think this is the typical assessment, but it points out to me that maybe it's not that simple. In these games Defect is the opposite of Cooperate. But Compete is also the opposite the Cooperate. It's not synonymous with Defect, but it overlaps a lot. And groups who compete get global social benefits as well under certain conditions.
* Which leads me to think that Symmetry is maybe the key idea for me. You don't just need C-C outcomes, but the idea is that you want C-C and D-D outcomes and avoid the C-D cells. If you can make the case for this, then homogeniety of decision processes becomes high utility.
* The PGG model (and maybe most game theory) doesn't really dig into the idea of the individual decision arising from a series of cognitive operations. Nor is there any learning. I suppose you could say that learning to become a cooperator from being a defector is identical to replacement in their models. But if there are environmental context effects on learning, these might affect that process (i.e., change the replacement function). Both the idea of homogenizing cognition across individuals and the effect of reinforcement learning in symmetry-dominated groups (which will lead to C being rewarded over D and increase altruism) require doing some cognitive psychology on the actors.
* The issue of the virtuous D-D conditions may be complex. It seems to me to be the place where capitalism occurs -- competition for ideas, information, valuation seems to emerge from D-D interactions. I have a strong intuition that a high percentage of dyadic capitalist interactions are D-D. E.g., prices set on supply/demand rather than value to the purchaser, any "trading" that is based on estimates of future value (the transaction should only occur when the seller and buyer have different estimates). Is this an unusual idea? How common or useful are virtuous D-D interactions versus C-C interactions in capitalist interactions (buy-and-hold long from an IPO or bond is a C-C, you cooperate in providing capital, there's a communal gain from the investment growth and the rewards benefit all participators).
* The the communal action model of the PGG, D-D can be better than C-D if the group action has some non-linearity to it, e.g., it requires a certain number of C actors to gain the benefit. Then if some Cooperate but not enough to gain the benefit, it's a communal loss. This is a very minor version of the "virtuous D-D" where D-D > C-D.
The abstract from the Nature paper:
The model these authors use (and appears to be standard) is the Public Goods Game (PGG). In this, a group of actors each chooses to cooperate at some cost 'c' and the benefit of the cooperation is distributed across the whole group, both cooperators and defectors. Defecting is still the dominant strategy because you gain the benefit without paying the cost. The question is, how do you get a group to cooperate under these conditions?
One idea is that there are 'punishers' who identify and punish the defectors, making defecting no longer a viable strategy. The authors are tackling the question of how you get punishers into a community and come up with some conditions under which the most common stable equilibrium is a mix of cooperators and punishers.
Some points of basic difference in thinking:
* The PGG game is a nice extension to communal activities. And my idea of having enforced social norms seems to imply the existence of some sort of enforcer (punisher). How social norm enforcers get into the system seems more basic than my thinking.
* But it doesn't seem to consider the idea of competing communities. Those would seem to enforce a certain kind of punishment as well. If your community doesn't cooperate and gain the benefits, a neighboring community (tribe) will out-compete you.
* The PGG game also implicitly leaves the D-D cell as a very bad thing. I think this is the typical assessment, but it points out to me that maybe it's not that simple. In these games Defect is the opposite of Cooperate. But Compete is also the opposite the Cooperate. It's not synonymous with Defect, but it overlaps a lot. And groups who compete get global social benefits as well under certain conditions.
* Which leads me to think that Symmetry is maybe the key idea for me. You don't just need C-C outcomes, but the idea is that you want C-C and D-D outcomes and avoid the C-D cells. If you can make the case for this, then homogeniety of decision processes becomes high utility.
* The PGG model (and maybe most game theory) doesn't really dig into the idea of the individual decision arising from a series of cognitive operations. Nor is there any learning. I suppose you could say that learning to become a cooperator from being a defector is identical to replacement in their models. But if there are environmental context effects on learning, these might affect that process (i.e., change the replacement function). Both the idea of homogenizing cognition across individuals and the effect of reinforcement learning in symmetry-dominated groups (which will lead to C being rewarded over D and increase altruism) require doing some cognitive psychology on the actors.
* The issue of the virtuous D-D conditions may be complex. It seems to me to be the place where capitalism occurs -- competition for ideas, information, valuation seems to emerge from D-D interactions. I have a strong intuition that a high percentage of dyadic capitalist interactions are D-D. E.g., prices set on supply/demand rather than value to the purchaser, any "trading" that is based on estimates of future value (the transaction should only occur when the seller and buyer have different estimates). Is this an unusual idea? How common or useful are virtuous D-D interactions versus C-C interactions in capitalist interactions (buy-and-hold long from an IPO or bond is a C-C, you cooperate in providing capital, there's a communal gain from the investment growth and the rewards benefit all participators).
* The the communal action model of the PGG, D-D can be better than C-D if the group action has some non-linearity to it, e.g., it requires a certain number of C actors to gain the benefit. Then if some Cooperate but not enough to gain the benefit, it's a communal loss. This is a very minor version of the "virtuous D-D" where D-D > C-D.
The abstract from the Nature paper:
Social diversity promotes the emergence of cooperation in public goods games
Francisco C. Santos1, Marta D. Santos2 & Jorge M. Pacheco2
- Institut de Recherches Interdisciplinaires et de Développements en Intelligence Artificielle (IRIDIA), Computer and Decision Engineering Department, Université Libre de Bruxelles, B-1050 Brussels, Belgium
- ATP-group, Centro de Fisica Teórica e Computacional (CFTC) and Departamento de Física da Universidade de Lisboa, Complexo Interdisciplinar, Av. Prof. Gama Pinto 2, 1649-003 Lisboa, Portugal
Correspondence to: Jorge M. Pacheco2 Correspondence and requests for materials should be addressed to J.M.P. (Email: pacheco@cii.fc.ul.pt).
Top of pageAbstract
Humans often cooperate in public goods games1, 2, 3 and situations ranging from family issues to global warming4, 5. However, evolutionary game theory predicts4, 6 that the temptation to forgo the public good mostly wins over collective cooperative action, and this is often also seen in economic experiments7. Here we show how social diversity provides an escape from this apparent paradox. Up to now, individuals have been treated as equivalent in all respects4, 8, in sharp contrast with real-life situations, where diversity is ubiquitous. We introduce social diversity by means of heterogeneous graphs and show that cooperation is promoted by the diversity associated with the number and size of the public goods game in which each individual participates and with the individual contribution to each such game. When social ties follow a scale-free distribution9, cooperation is enhanced whenever all individuals are expected to contribute a fixed amount irrespective of the plethora of public goods games in which they engage. Our results may help to explain the emergence of cooperation in the absence of mechanisms based on individual reputation and punishment10, 11, 12. Combining social diversity with reputation and punishment will provide instrumental clues on the self-organization of social communities and their economical implications.
Tuesday, July 7, 2009
IPDG
In a standard "prisoner's dilemma" game, the payoff matrix is set up to make Defection the dominant strategy. The concept captures a lot of situations where you could choose to do something helpful to others (= Cooperate, in the IPDG) and if everybody cooperates, everybody wins. But in many of these situations, if everybody else is cooperating, you can personally maximize by Defecting. You gain the benefits of everybody else cooperating, but you don't bear the cost of cooperating.
Example: picking up litter. If everybody does it, the environment gets clean. But if everybody else is doing it, you can stop doing it and get the benefit of the clean environment (somebody else will pick it up) without doing the work. But, if everybody starts to Defect and you still Cooperate, now you get all the cost and no real benefit.
An interesting payoff matrix looks something like:
Coop/Coop: +1/+1
Defect/Coop: +2/-5 (and vice versa)
Defect/Defect: -1/-1
In these kinds of games, the math is pretty clear that absent external knowledge of what the other actor will do, you are best served to Defect. In iterated games where you have some knowledge over time of what the other actor does, the tit-for-tat strategy is optimal (do to the other person whatever they did to you last, but cooperate on the first trial).
The math implies a puzzle about why people engage in altruism -- why cooperate at all? Are people not rational? Or do they expect some return from their reputation -- if you cooperate and re-engage the same person later and they remember you, perhaps they'll cooperate back and you'll get a return on your invested cost. The math seems to depend on the probability of reciprocation.
Douglas Hofstadter, however, points out another reason to cooperate which he calls Superrationality. The idea is that if you know your opponent/partner is extremely insightful, you might both be able to reason in a way that leads to similar conclusions. E.g., you both realize the game is Defect dominant, so you'll both initially think to defect. But you both also realize that given that you will both choose the same option, you could safely cooperate knowing the other person will also find the reason to cooperate and you'll get to the C-C outcome.
Whether people actually think that way is one thing, but it does point out the value of symmetry in the game. Any time 2 actors choose the same action, the result is "fair" to both of them and optimal for them combined if they both cooperate. The payoff matrix described above is also designed to maximize the joint outcome in the C-C cell.
If we extend the IPDG beyond two-person interactions to think of the welfare of a collection of individuals (who each interact in pairs), it's clear that maximizing the community welfare is done by maximizing the number of C-C interactions. This is a situation where you personally maximize your utility by Defecting, but your community is maximized by Cooperating.
If we imagine a large number of competing communities out in the world, what is the optimal way for a community to out-compete other communities?
Two things that will help a lot are: (1) social norms defined in the community that encourage/require cooperation as much as possible and (2) in-group/out-group biases.
On (1), communities with strong social norms that require people to set aside personal gain and cooperate for communal benefit will out-compete more individualistic communities. In fact, for the specific payoff matrix above, you don't strictly need a cooperation/altruism directive, you can actually get the communal benefit mainly through symmetry. If you have a very homogeneous set of actors (who all think alike), they should tend to come to cooperate/defect decisions the same way and tend to end up in the C-C or D-D cells (which are community maximizing). Also, if there's any learning in the actors, experience with only C-C or D-D interactions will tend to reinforce Cooperating over Defection and the community will move towards general altruism.
On (2), it's obvious that if you want your community to out-compete other communities, you want to maximize Cooperation (altruism) within your community, but personally maximize utility outside and Defect (or at best tit-for-tat).
Curiously, this seems to imply that if you have many communities competing over a long period of time and success is related to how well your community structure maximizes outcomes, communities that construct very strong social norms, homogeneous thinking and strong out-group biases should tend to win. Does this provide insight into the prevalance of groups that organize around religions that are particularly controlling, nationalism (and strong cultural expectations) and even racism?
Example: picking up litter. If everybody does it, the environment gets clean. But if everybody else is doing it, you can stop doing it and get the benefit of the clean environment (somebody else will pick it up) without doing the work. But, if everybody starts to Defect and you still Cooperate, now you get all the cost and no real benefit.
An interesting payoff matrix looks something like:
Coop/Coop: +1/+1
Defect/Coop: +2/-5 (and vice versa)
Defect/Defect: -1/-1
In these kinds of games, the math is pretty clear that absent external knowledge of what the other actor will do, you are best served to Defect. In iterated games where you have some knowledge over time of what the other actor does, the tit-for-tat strategy is optimal (do to the other person whatever they did to you last, but cooperate on the first trial).
The math implies a puzzle about why people engage in altruism -- why cooperate at all? Are people not rational? Or do they expect some return from their reputation -- if you cooperate and re-engage the same person later and they remember you, perhaps they'll cooperate back and you'll get a return on your invested cost. The math seems to depend on the probability of reciprocation.
Douglas Hofstadter, however, points out another reason to cooperate which he calls Superrationality. The idea is that if you know your opponent/partner is extremely insightful, you might both be able to reason in a way that leads to similar conclusions. E.g., you both realize the game is Defect dominant, so you'll both initially think to defect. But you both also realize that given that you will both choose the same option, you could safely cooperate knowing the other person will also find the reason to cooperate and you'll get to the C-C outcome.
Whether people actually think that way is one thing, but it does point out the value of symmetry in the game. Any time 2 actors choose the same action, the result is "fair" to both of them and optimal for them combined if they both cooperate. The payoff matrix described above is also designed to maximize the joint outcome in the C-C cell.
If we extend the IPDG beyond two-person interactions to think of the welfare of a collection of individuals (who each interact in pairs), it's clear that maximizing the community welfare is done by maximizing the number of C-C interactions. This is a situation where you personally maximize your utility by Defecting, but your community is maximized by Cooperating.
If we imagine a large number of competing communities out in the world, what is the optimal way for a community to out-compete other communities?
Two things that will help a lot are: (1) social norms defined in the community that encourage/require cooperation as much as possible and (2) in-group/out-group biases.
On (1), communities with strong social norms that require people to set aside personal gain and cooperate for communal benefit will out-compete more individualistic communities. In fact, for the specific payoff matrix above, you don't strictly need a cooperation/altruism directive, you can actually get the communal benefit mainly through symmetry. If you have a very homogeneous set of actors (who all think alike), they should tend to come to cooperate/defect decisions the same way and tend to end up in the C-C or D-D cells (which are community maximizing). Also, if there's any learning in the actors, experience with only C-C or D-D interactions will tend to reinforce Cooperating over Defection and the community will move towards general altruism.
On (2), it's obvious that if you want your community to out-compete other communities, you want to maximize Cooperation (altruism) within your community, but personally maximize utility outside and Defect (or at best tit-for-tat).
Curiously, this seems to imply that if you have many communities competing over a long period of time and success is related to how well your community structure maximizes outcomes, communities that construct very strong social norms, homogeneous thinking and strong out-group biases should tend to win. Does this provide insight into the prevalance of groups that organize around religions that are particularly controlling, nationalism (and strong cultural expectations) and even racism?
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