Monday, September 25, 2006
Friday, September 22, 2006
Chomsky, in a classical paper, discusses Skinner's book Verbal Behavior and the associated attempts of behaviorists to explain Language Acquisition as just another complex behavior learned entirely through behaviorist mechanisms of classical and operant conditioning.
Chomsky himself clarifies the difference between cognitive and behaviorist explanations as follows:
It is important to see clearly just what it is in Skinner's program and claims that makes them appear so bold and remarkable, It is not primarily the fact that he has set functional analysis as his problem, or that he limits himself to study of observables, i.e., input-output relations. What is so surprising is the particular limitations he has imposed on the way in which the observables of behavior are to be studied, and, above all, the particularly simple nature of the function which, he claims, describes the causation of behavior. One would naturally expect that prediction of the behavior of a complex organism (or machine) would require, in addition to information about external stimulation, knowledge of the internal structure of the organism, the ways in which it processes input information and organizes its own behavior. These characteristics of the organism are in general a complicated product of inborn structure, the genetically determined course of maturation, and past experience. ...... The differences that arise between those who affirm and those who deny the importance of the specific "contribution of the organism" to learning and performance concern the particular character and complexity of this function, and the kinds of observations and research necessary for arriving at a precise specification of it. If the contribution of the organism is complex, the only hope of predicting behavior even in a gross way will be through a very indirect program of research that begins by studying the detailed character of the behavior itself and the particular capacities of the organism involved.
It would be prudent for me to clarify at the outset, that I am a Cognitivist and definitely see the merits of Chomsky's arguments and the inadequacy of the potentially misguided attempts of Skinner and other behaviorists to apply the behaviorist concepts and results derived from animal studies to the study of semantics or how words get associated with a particular meaning and are used in particular contexts - either due to their prior association with a stimulus (stimulus control...something like classical conditioning in which the word 'red' gets associated with the property redness of an object and the internal visual response or qualia of redness that is produced automatically in response to the stimulus redness causes a conditioned association between "red' and the qualia redness) or because the word or sentence was reinforced variably through various mechanisms like self-reinforcement, reinforcement-by-way-of-praise etc.
I definitely do not concur with Skinner's arguments and definitions, and Chomsky show to some extent an understanding of the behaviorist concepts (especially in section II), but he also at times shows his profound lack of appreciation of finer subtleties of behaviorist concepts. For example:
In the book under review, response strength is defined as "probability of emission" (22). This definition provides a comforting impression of objectivity, which, however, is quickly dispelled when we look into the matter more closely. The term probability has some rather obscure meaning for Skinner in this book.9 We are told, on the one hand, that "our evidence for the contribution of each variable [to response strength] is based on observation of frequencies alone" (28). At the same time, it appears that frequency is a very misleading measure of strength, since, for example, the frequency of a response may be "primarily attributable to the frequency of occurrence of controlling variables" (27). It is not clear how the frequency of a response can be attributable to anything BUT the frequency of occurrence of its controlling variables if we accept Skinner's view that the behavior occurring in a given situation is "fully determined" by the relevant controlling variables.
Here Chomsky has mixed and made a mess of the two separate concepts and processes in behaviorism- classical and operant conditioning. In the above paragraph, the definition of response in terms of 'probability of occurrence' is in terms of operant conditioning - wherein responses are autonomously generated by an organism irrespective of any stimulus (leave aside the case of discriminating stimulus as of now) that is present - for e.g. a bar-press- and based on the reinforcing stimulus that is presented to the organism , post response, the response strength or probability that the response would occur, autonomously, in future , increases. This is mixed up with the earlier concept of stimulus control (or classical conditioning) wherein controlling variables (or conditioned stimulus) relevant to a situation lead to an utterance or verbal behavior. This determining of verbal behavior due to presence of a a conditioned stimulus (reflexive language) would be a different mechanism form that used in deliberative language , wherein, an utterance is produced voluntarily and in defiance of its surrounding stimuli, but the probability of that occurrence is in proportion to its history of reinforcement. By mixing the two concepts, Chomsky just manages to show his ignorance and lack of appreciation of the behaviorist concepts/ mechanisms.
But my gripe with Chomsky is more for the change in focus that he has managed to pull off, with the study of semantics taking a backseat to the study of grammar or syntax. In my limited comprehension, I am unable to appreciate, how concepts of Universal Grammar, however much relevant and innate, could be a substitute for a proper analysis of language acquisition in terms of an ability to not only mastered the grammar, but also the semantics. Grammar or Grammar acquisition, per se, does not inform much about the actual and most relevant aspects of language acquisition- viz. semantics and pragmatics.
Addressing semantics, would be a task for a later day (and perhaps for a more capable person than me), but today I would like to tentatively propose a role for behaviorist concepts of reinforcement or operant conditioning as relevant to the general ability to understand and produce language and also to the general difference in talkativeness (and listening-ness, if there exists such a concept) between different people
Language acquisition should be broken into two components - a language understanding (or hearing) component and another language production (or speaking) component. It is a fact that the first component related to language understanding develops prior to language production. Also, it should be kept in mind that language is essentially a two person activity, with the utterance of one acting as (reinforcing) stimulus for the other and the utterance of another acting as a response.
The Hearing (or language understanding) activity:
This language component is used for understanding the meaning of utterances (say spoken language as opposed to written or depicted using sign language) and is relatively independent of language production.
Response is parsing the spoken sentence into words and by analyzing the syntax and meaning of the words constructing a mental image of the intention, beliefs, knowledge and possible behavior of the person who spoke the sentence and integrate that knowledge with the representation and expectation of the world in general.
Reinforcing stimulus is observing the behavior of the person who spoke the sentence to be in accordance with that earlier constructed expectation and prediction (the hearing response). It is assumed that an external act (whether negative or positive) that is in accord with an internal expectation would be rewarding in the sense that it would satisfy and reduce the internal drive to know in general - and to know the future in particular. Alternately, it can be posited that the state of not knowing clearly about the future is a state of unbearable tension and the uncertainty associated with the world is a negative stimulus (property) associated with the world. By hearing and understanding a sentence uttered by someone else, some of this aversive stimulus (uncertainty) is removed and thus by negative reinforcement (removal of an aversive stimulus) any act of hearing (or understanding...or refining the predictions regarding the world) is inherently rewarding irrespective of whether the actual outcome is as per the constructed expectations. Positive reinforcement of having the expectation met would result in strengthening of the hearing response. This is a general strengthening of the hearing response (or the response of creating expectations from heard utterances) and is independent of the actual content of that expectation. Thus, if an effort to construe meaning from an utterance was followed by a positive reinforcement of having that meaning verified, then the propensity of construing meaning from utterances would increase in strength. It is posited that this behaviorist mechanism is one of the strong motivating factor that encourages a child to understand the language of its parents/ society.
Although as adults, parsing sentences into words and extracting meaning from it seems automatic to us, for a child extracting meaning from a string of syllables is a very effort full activity, and the fact that doing so leads to positive reinforcement would encourage the child to pay attention to the hearing and understanding activity and increase their habit strength. The alternate mechanism to such a behavioristically mediated hearing acquisition could be claiming that development of language understanding is under genetic control and is similar to imprinting or genetic unfolding. This claim is weakened by an ability of mature adults to learn a foreign language. Thus, if this mechanism uses imprinting alone, it should be possible only under a critical period of childhood and not amenable to acquisition in adulthood. the fact that children are able to learn second languages faster and better than adults and some evidence form study of feral children as to a critical period necessary for first language acquisition, point to a mixed role of genetic factors like imprinting and behaviorist factors like reinforcement of the 'predicting the world capability'.
The Speaking (or language production) activity:
This language component is used for production of meaningful utterances (say spoken language as opposed to written or depicted using sign language) and follows the relevant stage of language comprehension.
Response, in this case, would be constructing a valid, informative sentence by piecing together words that denote the shared meaning of objects and situations and uttering a valid meaningful sentence directed towards another listener. The intention for the utterance could be pedagogic (informing or teaching a fact to someone about whom you care), instrumental (using the person spoken to as a tool to achieve desired outcome), empathetic (sharing thoughts, feeling etc with the other person) or of some other kind.
Reinforcing stimulus, in this case would be observing the behavior of spoken-to person and discovering that the relevant information/ facts have been conveyed and understood properly. This reinforcing stimulus, can take the form of either observing the actual behavior, inline with the intended meaning of the utterance, or can be as subtle as deciphering the facial expressions of the listener for signs of understanding. In elongated verbal conversations, a verbal utterance by the listener, may serve as a reinforcing stimulus, and substitute for the outward behavior/ understanding expression (This for example is relevant in telephonic conversations and is one of the reasons children learn to speak on telephones later than they learn talking to adults face-to-face). The stimulus is reinforcing because it satisfies an earlier drive to control (use the other person as a tool for ones ends), the drive to share (the drive for belongings and intimacy) or the drive to inform (pedagogic drive).
Speaking, or constructing valid sentences by stringing syllables together, is again an effortful activity, and though as an adult it may seem effortless, strong motivations have to be present in childhood, for development of proper language production capabilities. The reinforcing stimulus, of having one’s intentions met, by observing the behaviour of the listener, provides the required incentive and mechanism whereby the habit strength of generating meaningful utterances is strengthened.
How to test for this theory:
It is clear from above discussion, that Hearing or language understanding predominantly relies on the drive for meaning or for predicting the world as its guiding mechanism, whereby the speaking or language production relies on other mechanisms involving drive for control , empathy and instruction.
I was recently introduced to Terror Management Theory (TMT) while reading a post by Mixing Memory on how TMT may influence Art Appreciation and I believe a similar study can be used for determining the ability of language understanding to provide meaning.
Specifically, if some subjects are primed with thoughts of death (as opposed to a neutral control topic) , then may exhibit a stringer drive for subsequent activities that give rise to a sense of meaning. This manipulation could be in the form of thinking of the September 11 attacks which increase mortality salience or by asking the participants to read the following instructions designed to increase their mortality salience:
Please briefly describe the emotions that the thought of your own death arouses in you.
Jot down, as specifically as you can, what you think will happen to you physically as you die and once you are physically dead.
The other half of the participants should be made to respond to similar instructions, but in reference to an upcoming exam rather than death.
Afterwards, both groups should be allowed an activity that involves language understanding (say listening to a meaningful audio radio program or conversation) and one that does not involve language understanding (say painting or sketching a drawing). The respondents should then be asked which activities (language comprehension related or visual painting related) they found more satisfying or meaningful. If those who had high mortality salience also showed a preponderant satisfaction by indulging in language comprehension related activities as opposed to control group and control task, then this would be a strong indicator of the importance of meaning formation in the motivation for language comprehension. A particular confound here is the second task ( as per the Mixing Memory task, Art may also serve as a Meaning generator and hence not be a suitable control task and should be replaced by a meaningless task like repetitive manual action task) and it should be ensured that this task does not involve Meaning generation. One control that seems appropriate is language production, as the mechanism underlying that is posited to be different from Meaning acquisition. Thus, the control activity could be related to language production (say allowing the participants to make an extempore speech on a topic for 20 minutes).
Finally, I would like to highlight a real life experiment. Those who participate in a ten day Vipassana Meditation camp are not allowed to speak for those ten days. As such, the amount they hear is also limited to some morning/ evening hymns (that may involve more music than language) and apart from that no other hearing or language understanding takes place. After the ten day speaking fast, when the participants talk to each other, one finds great meaning in the conversations. This may be a case of reduction of the meaning drive, after its prolonged starvation.
Also, the traits like loquaciousness may be explained partially in terms of the different underlying needs for control, empathy, instruction etc that give rise to the talking behavior, as well as the particular history of reinforcement that the subject has undergone, thus making that trait subject to both genetic and environmental influences.
To end on a lighter note, please note the Mixing Memory’s evaluation of such studies linking TMT and Art.
I've never really hung out in a social psychology laboratory, but here is how I picture a typical day in one. There are some social psychologists sitting around, drinking some sort of exotic tea, and free associating. One psychologist will say the name of a random social psychological theory, and another will then throw out the first thing that comes into his or her head. They'll write each of these down, and the associations will then become the basis for their next several research projects. OK, so that's probably not really what's going on, and I suppose there's a more scientific method to the social psychologist's madness, but occasionally I come across a study that makes me wonder. And the great thing about having a blog is that I get to write about it when I do. Today's example: terror management theory and modern art
I am, at present, camping in the filed of Social Psychology and thus take the privilege of suggesting a more bizarre study that could possibly prove what we may all intuitively know - that the motivation for hearing something is because we derive meaning from it! (Remember the cocktail party effect, wherein we are able to selectively listen to the conversation of interest- or one that is most meaningful to us). As the say, no research is that abstruse as to not get funded. So all you students out there, anyone care to conduct such a research (and prove me right)!Sphere: Related Content
Thursday, September 21, 2006
I have recently become quite interested in collaborative writing and was initially thinking of submitting a book proposal to the Psychology Press for their series on Cognitive Neuroscience. That option is still open and if someone wants to collaborate you are welcome to contact me (write to : sandygautam[AT]yahoo[DOT]com) !!
But what I have discovered is that there are other emerging models of collaborative publishing. Triggered by news regarding a Global Text Project, which aims to create 1000 online textbooks in due course of time, I came across Wikibooks. It seems Wikibooks already has a free Cognitive Psychology and Neuroscience Textbook that one can contribute to and refine and is featured as the book for the month. Have just casually browsed through one of the chapters, but it seems an interesting idea and one to which we bloggers can lend our expertise. This should definitely help third world students who may lack the monetary resources to buy costly textbooks and may have to rely on online resources. However the 'chapters' are too sketchy and more of Wikepedia entries than a summary of relevant research (with citations) in that field.
That brings me to the Citezendium, a new Citizen's Compendium, which aims to do away with the deficiencies of the Wikepedia and encourage Academics to get involved with the collaborative encyclopedia initiative with special powers and responsibilities given to the experts over the normal contributing authors. Would definitely like to contribute there. hopefully, the readers of this blog will also find these collaborative initiatives interesting and contribute in their own small ways.
While the recent experiments with the Carmelite nuns have been unable to identify a definitive GOD spot in the brain, it seems that the pre-surgery electrical stimulation of the brain of an epileptic patient has shed light on a potential ghost spot.
When the Temporo-pareital junction (TPJ) was stimulated, the woman felt the presence of a shadow behind her that was taking the same posture as herself.
The woman described the shadow person as young, silent, and mirroring her position as she lay on her back. "He is behind me, almost at my body, but I do not feel it," she said, according to the doctors.
Next, the researchers stimulated the same spot in the woman's brain as she sat up with her arms wrapped around her knees.
Again, the woman sensed the shadow presence. This time she said the man was sitting behind her and had his arms around her.
Lastly, the woman sat up, holding a card in her right hand, for another brain test that involved stimulating the same brain area. She once more sensed the shadow person.
"He wants to take the card. He doesn't want me to read," the woman reportedly said.
This has interesting implications for Schizophrenia research and the Nature article does hint at that. Specifically, abnormal brain activity in the TPJ may give rise to a feeling of a shadowy person following the schizophrenic subject always. This sense of being watched may give rise to a host of related syndromes. This may give rise to a sense of paranoia, delusions of persecution , delusions of alien control (when hugging your knee it may seem the shadow was using its hand to force yours or the prior act of bending forward by the shadow may be implicated as causing oneself to bend forward) and other delusions like the alien hand syndrome. Interesting to note that the epileptic woman in question assigns bad motives to the shadow. ("he doesn't want me to take the card")
It would be interesting to investigate, what abnormalities, if any, in the TPJ are present in the Schizophrenics subjects.Hat tip: Omni Brain Sphere: Related Content
Wednesday, September 20, 2006
A recent research by Rizzolatti et al, has once again come up with exciting new evidence that may be construed as evidence for the linkage between mirror neuron system in humans and the evolution of language.
This study has been able to establish that the same pre-motor cortical areas are engaged when one is performing an action like kicking as well as when one is just listening to the word 'kicking'. This effect is found only for literal action words and not the same word 'kicking' when used metaphorically as in "kicking off".
It is just a little stretch of imagination from here to making case for the link between language and mirror neurons.
Specifically, it is plausible, that when the mirror neurons gave an ability to humans to represent an action (irrespective of whether it was performed by self or by others) in the brain, then this capacity to abstract an action from its performer may have been the beginning of the symbolic representation capacity whereby a symbol that is remote from the original object can represent that object. This symbolic capacity to represent activation in brain region with both an action performed by self as well as others may have later lead to the first linguistic semantic words that would have been associated with such representations. The data that the action words activate the same pre motor regions as actual actions makes this hypothesis more attractive.
I know that mirror neurons are not exactly that popular in blogosphere, but still some food for thought.
Tuesday, September 19, 2006
I was browsing a write-up on Causal reasoning by Mixing Memory, and came across this article by Lagnado et al, regarding the Causal Structure underlying causal reasoning.
In brief , Causal reasoning refers to that ability of the humans by which they can classify some events as causes and some events as effects and also determine either deterministically or probabilistically as to which effects are caused by which causes. In simple words, the ability to assign causes to effects.
Historically, Causal reasoning has focused on the statistical methods of covariance or correlation between two events and used the strength of the correlation to calculate and predict the causal relation between the two events. This suffers from several drawbacks like inability to determine the direction of causation or the inability to rule out a third common cause of which the two observed events are the effects.
Langrado et al, in their paper, present a refreshing new perspective on causal reasoning by differentiating between the qualitative Causal Structure between two or more events and the quantitative Causal Strength of that relationship. For example, a causal structure may causally relate the presence of fever with bacterial infection thus identifying bacterial infection as a cause of fever; but the causal strength between bacterial infection and fever would determine what probability we assign to a particular case of fever to have been caused due to bacterial infection (diagnostic learning) or the probability that given bacterial infection a person would develop fever (predictive learning).
The authors contend that the issues involved in causal strength learning and causal structure learning are different and should be addressed differently. Further, they contend that most of the historical research has been limited to causal strength learning, ignoring the prior and more fundamental stage of causal structure learning; as in their theory, the causal strength of any relation can only be learned once one has some a priori qualitative assumptions about the underlying causal relationships. Their paper thus focuses what cues/mechanisms are involved in the formation of the causal structure.
Causal-model theory was a relatively early, qualitative attempt to capture the distinction between structure and strength. According to this proposal causal induction is guided by top-down assumptions about the structure of causal models. These hypothetical causal models guide the processing of the learning input. The basic idea behind this approach is that we rarely encounter a causal learning situation in which we do not have some intuitions about basic causal features, such as whether an event is a potential cause or effect. If, for example, the task is to press a button and observe a light, we may not know whether these events are causally related or not, but we assume that the button is a potential cause and the light is a potential effect. Once a hypothetical causal model is in place, we can start estimating causal strength by observing covariation information. The way covariation estimates are computed and interpreted is dependent on the assumed causal model.
They list the cues that humans use to form their Causal structures as
- Statistical relations
- Temporal order
- Prior knowledge
Before discussing, in depth, each of these cues and how they may affect causal reasoning, it is instructive to note that the concept of a Causal Structure underlying a given set of phenomena is quite close to the idea of a Cognitive Map underlying a given environment (say the maze or the mouse trap). While the latter is a spatial mental map of the objects in the surrounding 3-D space, the former may be conceived as a causal mental map of events in the temporal dimension. The reason I am using this analogy is to contrast the cues used in formulating a Causal structure with the different learning mechanisms used by mice to form a cognitive map of the mouse trap. The contention is that the same cognitive mechanisms are involved and also that these mechanisms are structured and unfold in a developmentally guided and staged manner.
The first cue to form a Causal structure or link two or more events is that of statistical relations. Here, correlation information between the events, as well as their conditional independences are used to arrive at a set of Markov equivalent causal models. Much of the learning is associative, probabilistic and maybe latent. It may not be accessible to consciousness and the learning of causal structure is more implicit, than explicit. For example, the regularities in the data may give rise to a fuzzy causal structure, where tentative causal relations are posited. Suppose from the data, it is determined that A and B are perfectly correlated. The person will have a strong sense of causation between A and B, but would be unable to determine the direction of causation. similarly if 3 events A,B and C are correlated, we would not be able to determine the directions of causation. This mechanism is very much similar to the latent learning mechanism exhibited by the mice in the mouse trap.
The second cue to form a causal structure that we consider here is that of Intervention. Here, human intervention takes place by affecting one of the events (potential cause) and by basis of that intervention or exercised choice, experiment to find out what effect that variable has on the outcome (effect). To more rigorously define Interventions, let me quote from the paper.
Informally, an intervention involves imposing a change on a variable in a causal system from outside the system. A strong intervention is one that sets the variable in question to a particular value, and thus overrides the effects of any other causes of that variable. It does this without directly changing anything else in the system, although of course other variables in the system can change indirectly as a result of changes to the intervened-on variable. What is important for the purposes of causal learning is that an intervention can act as a quasi-experiment, one that eliminates (or reduces) confounds and helps establish the existence of a causal relation between the intervened-on variable and its effects.
Suppose A and B have been found to be correlated. Further suppose that the happening of event A and B is under the control of the human subject. Then one can intervene to cause A and observe whether B occurred. If so the direction of causation is from A -> B. On the other hand if by intervening the human subject caused B to happen and did not observe A, then one could conclude that B does not cause A. To make the example concrete, consider event A as 'Fire' and event B as 'Smoke'. We find that Fire and Smoke are correlated. By intervening and conducting experiments whereby we can control the occurrence of 'fire' or 'smoke' we can come up with correct causal relation that 'fire' -> 'smoke'
Consider again, a 3 event situation whereby the relation between two causal events (A and B) and an outcome (C) has to be ascertained. Specifically, by intervening and causing A sometimes and B other times, and observing the happening of C we could ascertain the causal structure as to whether A->c or B-> C. The situation is not too different than the vicarious trail and error learning exhibited by a mouse when at a choice point. There, the mice has to, by trail-and error choosing of either right/left black /white turnings, learn which stimulus is associated with food (outcome). Thus, intervention mechanism is nothing but the refined vicarious trial-and-error learning.
The third, and perhaps the most important, mechanism that is used to form the Causal structure is Temporal ordering. This is a very simple mechanism whereby events that are occurring prior to some other event can be the cause of that event, but not vice versa.
The temporal order in which events occur provides a fundamental cue to causal structure. Causes occur before (or possibly simultaneously with) their effects, so if one knows that event A occurs after event B, one can be sure that A is not a cause of B. However, while the temporal order of events can be used to rule out potential causes, it does not provide a sufficient cue to rule them in. Just because events of type B reliably follow events of type A, it does not follow that A causes B. Their regular succession may be explained by a common cause C (e.g., heavy drinking first causes euphoria and only later causes sickness). Thus the temporal order of events is an imperfect cue to causal structure.
This mechanism is the same as the one used by mice in searching for stimulus. When two events follow each other than an active search mechanism is used to identify the salient stimulus which may have been the cause of the event. The concept of temporal ordering implying causation is inherent in this learning mechanism as are concepts of spatial and temporal contiguity and proximity. This is the normal avoidance learning mechanism in mice and in human causal structure learning may be more engaged in and relevant to identifying the causes of events that are undesirable.
The fourth cue used for identifying causal structure, that the authors do not touch on, but do hint in terms of highlighting the importance of causal mechanisms; but that I propose nonetheless, is that of causal chains construction and elaboration. This basically involves breaking the simple A-> B with intermediate and competing C, D, E etc and intervening and conducting experiments to come up with the correct causal chain. Thus, A->B may be refined as A->C->D->B or A-> E->B and experimentation done to narrow down on a particular causal chain.
This is similar to the hypothesis learning involved in mice and depends on a cognitive capacity to sequence events . Also this is normally exhibited in approach behavior and this elaboration of causal chain may be more relevant to the desirable outcomes that human subjects want to happen and all the small intermediate steps of they need to cause to make the final outcome happen.
The fifth, and for now final, cue that is used in the formation of causal structure is prior knowledge. The authors define it as follows:
Regardless of when we observe fever in a patient, our world knowledge tells us that fever is not a cause but rather an effect of an underlying disease. Prior knowledge may be very specific when we have already learned about a causal relation, but prior knowledge can also be abstract and hypothetical. We know that switches can turn on devices even when we do not know about the specific function of a switch in a novel device. Similarly we know that diseases can cause a wide range of symptoms prior to finding out which symptom is caused by which disease. In contrast, rarely do we consider symptoms as possible causes of a disease.
My take on prior knowledge is something close to that, but slightly different. The subject forms a general idea of which events are causes and which effects and also the general relationship between a primary cause and a desired/undesired later final outcome. Though, the intervening small steps of the causal chain may not be present, and thus no formal corroborating data based proof may be there, yet one can deduce the causal relationship between the primal cause and the later final outcome, ignoring the intermediate minor events down the line. A case in point would be food aversion learning, whereby one single vomit following consumption of say a spoiled food that was taken hours ago, may result in a strong automatic association and learning of that food as the cause of vomit and lead to avoidance of (or escape from) that food.
To me this mechanism is the same as that exhibited by the mice when they learn the spatial orientation in the mouse trap and are able to exhibit novel escape learning.
This summarizes the analogy between the causal learning and normal learning as of now. Will touch on the qualitatively different next 3 (causal) learning mechanisms later. Sphere: Related Content
Monday, September 18, 2006
I have posted earlier about the similarities between the Universal Grammar concept associated with languages and the Universal Moral Grammar that Hauser has proposed. To take the analogy further, just as linguistic framing of a issue leads to different interpretations and effects in the person exposed to a sentence or a phrase or a discourse, so too it is apparent that when a moral dilemma is posed under different contextual situations or framed differently then they led to different appraisals by the same subject.
To begin with, one may note that Mixing Memory writes about the concept of personal and impersonal violations, as outlined by Greene et al, and associates them with the famous Moral Dilemma of one versus five lives on a railway track in two different conditions - the Footbridge and the Trolley. To explain the differences in responses of the people to the differing moral dilemma in the two conditions, the concept of impersonal and personal violations is introduced and it is posited that these involve different reactions in the brain - one utilizing the emotional brain, and the other a rational brain. However, I have elsewhere provided a more parsimonious explanation utilizing the stages of moral development that people are on and how that may lead to different outcomes for the same moral problem in the two conditions. Specifically those at stage 3 of good interpersonal relationship would differ in how they respond to the two dilemmas.
More relevant to our discussion here, is that the same effects could be explained by the differing framing of the Moral dilemma. In effect, the footbridge dilemma is framed in such a way as to activate the action predicate processing in a different way from the impersonal trolley condition. In the footbridge case, the action predicate is of an action involving two human beings- the action is deliberate pushing of another person- and hence of more negative connotation- than the corresponding impersonal action involving acting on an inanimate object- viz. pushing the trolley. Thus, when Action Predicate also becomes a significant player in the Moral Dilemma, then though the intention and consequence predicate may remain the same, it may lead to different evaluations of the Moral Sentence.
Second, one needs to pay attention to the effect of emotions that has been observed in the footbridge dilemma, as observed by Piercarlo Valdesolo and David DeSterno. They report that under positive affect, people are more apt to choose the more 'rational' utilitarian alternative of pushing the person down the footbridge. This clearly is due to different framing conditions. A big part of the Moral Language is definitely made up of affects as they often provide a reliable guide to instinctive moral behavior. Thus, b putting the subjects under positive affect may be tantamount to the same framing effects that are observed when concepts like Tax opposition are associated with happy sounding words like relief and thus frame the issue of taxation differently. By a similar sleight of hand, as humans do tend to associate happiness and 'happiness for largest number of people' in their mind, so the utilitarian ethic may dominate when the context surrounding the moral dilemma is of 'happiness' or positive affect. It remains to be seen, if arousing negative or other affects in the subjects lead to a decline in the utilitarian response.
Anyway, the results as they stand today, do not corroborate the Impersonal/Personal violation theory and the corresponding rational/emotional brain theory, because the results clearly show that the differential response when in positive affect footbridge condition is due to the different emotional significance attached to the dilemma in happy affect vs. neutral affect situations. If anything, in the happy affect situation, the affective influence in decision making was greater (as baseline emotional activity was greater), than in the control condition. To prove that rational decision making was strengthened in presence of positive affect, one would need to show a general increase in rational decision making when under positive affect, or if not, at least by taking MRI scan of these happy affect decision makers, show that rational brain centers were more engaged than emotional centers while making the happy-affect-utilitarian decision..
Till then, we have plenty of evidence supporting the other hypothesis that positive affect improves moral reasoning as positive affect may be an internal guide used for guiding moral action - if something feels good, then it perhaps is good. Case in point is studies that have earlier demonstrated that if a graduate student is in positive affect, then he/she is more likely to help strangers-- for example by picking up dropped books. Thus, positive affect may be intrinsically linked to more altruistic/ moralistic actions and framing a dilemma, such that it arouses positive or negative affect in the subject, may alter the way the dilemma is perceived and resolved by the subject.
The ever-thoughtful GNIF Brain Blogger has just published a brand new 7th edition of the Synapse. The articles range form thoughtful arguments for de-stigmatization of mental health issues to careful analysis of the recent vegetative-state-showing-consciousness studies. Sprinkled along the way are articles elaborating the trade off between proliferation and tumor suppression in human brain.
Have a happy reading!
As per this new Google initiative, one can now follow Fifi and other Chimpanzees in real-time as they roam around the Gombe Chimpanzee park using the Google Earth Featured Content. All you have to do is download Google Earth , choose the Jane Goodall's Gombe Chimpanzee Blog in the Featured Content section visible in the left sidebar and enjoy!
Although, I was not able to zoom in a live image of a chimpanzee ( as all of them were foraging in the dense forest and thus not visible), but with perseverance one may catch a live video of a chimp playing in an open area. Also, this would be of help to the primatologists amongst us, who could track the movements of these chimpanzees.
More power to Google!
Friday, September 15, 2006
How to maximise your bets : become a schizophrenic or damage your amygdala, the orbitofrontal cortex, or the right insular cortex!
A couple of recent news articles on neuroeconomics, lead to some surprising insights regarding how addictions like Gambling could be self-addictive and how some specific neurological malfunctioning may lead to people fairing better in games of chances and making more 'rational' gambles.
The first article in the New Scientist refers to a recent research by Chris Frith et al at University College London, UK in which the authors found that people who had been given dopamine agonists (like L-DOPA) were able to determine the winning strategy involved in a gambling game early then those who were given placebo. The study contained choosing symbols - some of whom were associated with large chances of winning, while others were associated with average chances and still others were associated with financial penalties and should ideally be learned as avoidable symbols.
What they found was that dopamine facilitated the early learning of the symbols that were associated with (monetary) winning outcomes or rewards as compared to controls, but had no effect on the learning of the avoiding or punishment symbols. This, they hypothesize is due to the fact that people get a Dopamine surge whenever 'rewarded' and when base dopamine levels are high (it has already been administered prior to the betting game) this leads to greater strength of dopamine reward signal , thus leading to faster learning of the winning strategy. The fact that dopamine does not affect the learning of negative outcomes, confirms that the effect selective and due to the 'rewarding' nature of dopamine as opposed to a general improvement in learning due to dopamine administration.
The participants played a computer game in which they were repeatedly shown pairs of unmatched symbols, and had to choose one or the other without being told anything about them beforehand.
Unknown to the participants, one symbol gave them an 80% higher chance of winning £1, whereas another symbol gave them only a 20% higher chance of winning. Other symbols incurred financial penalties.
The volunteers on dopamine prospered because they identified the winning symbols faster than the haloperidol treated patients. And the winning effect was more pronounced if they actually received money in the study.
The dopamine recipients only noticed winning symbols, however. The chemical did not appear to alert recipients to “losing” symbols.
Learning from losing is controlled by other chemicals in the brain, the most dominant probably being serotonin, a chemical linked with depression, Frith concludes.
This brings up some interesting scenarios. If one has started gambling somehow, then as one keeps gambling further, the successive wins would generate more and more dopamine surges (as baseline dopamine increases after a few wins), the gambler would start identifying the winning patterns, and the strength of winning patterns and rewards associated with them would continue to get stronger in the gambler's mind; there would be no corresponding effect on the learning of negative or losing strategies by him and consequently his learning would be skewed in such a way that winning outcomes would be disproportionately perceived as being rewarding as compared to the losing outcomes - thus in the gamblers mind loses are processed in a 'normal' way ; but wins or winning strategies are perceived differently in the sense that they would be learned more strongly, earlier and more persistently - as each win would result in more and more dopamine surge and thus skew the learning in favor of the winning strategy more and more. this is a vicious circle- the gambler is getting more and more dopamine surge and is also becoming better and better at identifying the winning strategies- thus its difficult to convince him otherwise that he is gambling in vain- what he doesn’t realize that he is not attaching a corresponding increased negative outcome to losses or is learning the losing strategies also at the same rate.
The other article is a good review of the field of neuroeconomics in the New Yorker. It touches on many current issues in neuroeconomics, but what is most relevant to us here is the concept of loss aversion, whereby people perceive losses of what they already have as more aversive than a wasted chance of making an equivalent or more gain. To paraphrase from the article:
If you present people with an even chance of winning a hundred and fifty dollars or losing a hundred dollars, most refuse the gamble, even though it is to their advantage to accept it: if you multiply the odds of winning—fifty per cent—times a hundred and fifty dollars, minus the odds of losing—also fifty per cent—times a hundred dollars, you end up with a gain of twenty-five dollars. If you accepted this bet ten times in a row, you could expect to gain two hundred and fifty dollars. But, when people are presented with it once, a prospective return of a hundred and fifty dollars isn’t enough to compensate them for a possible loss of a hundred dollars. In fact, most people won’t accept the gamble unless the winning stake is raised to two hundred dollars.
Further, the article notes that this loss aversion is due to the fact that under ambiguous situations (or situations that involve probabilistic estimates in face of incomplete information to make the probabilistic judgments), our 'emotional' brain takes precedence over the 'rational' brain and prevents us from making 'rational' decisions.
In one study, Camerer and several colleagues performed brain scans on a group of volunteers while they placed bets on whether the next card drawn from a deck would be red or black. In an initial set of trials, the players were told how many red cards and black cards were in the deck, so that they could calculate the probability of the next card’s being a certain color. Then a second set of trials was held, in which the participants were told only the total number of cards in the deck.
The first scenario corresponds to the theoretical ideal: investors facing a set of known risks. The second setup was more like the real world: the players knew something about what might happen, but not very much. As the researchers expected, the players’ brains reacted to the two scenarios differently. With less information to go on, the players exhibited substantially more activity in the amygdala and in the orbitofrontal cortex, which is believed to modulate activity in the amygdala. “The brain doesn’t like ambiguous situations,” Camerer said to me. “When it can’t figure out what is happening, the amygdala transmits fear to the orbitofrontal cortex.”
The results of the experiment suggested that when people are confronted with ambiguity their emotions can overpower their reasoning, leading them to reject risky propositions. This raises the intriguing possibility that people who are less fearful than others might make better investors, which is precisely what George Loewenstein and four other researchers found when they carried out a series of experiments with a group of patients who had suffered brain damage.
Further, the article notes that people with orbitofrontal, right insular or amygdala damage, are less fearful or are less able to integrate the fearful or 'emotional' response of the brain and are thus able to make decisions that are more risky then their normal counterparts. Thus, the counterintuitive conclusion that damages to these areas may make one a better investor/ gambler etc.
Each of the patients had a lesion in one of three regions of the brain that are central to the processing of emotions: the amygdala, the orbitofrontal cortex, or the right insular cortex. The researchers presented the patients with a series of fifty-fifty gambles, in which they stood to win a dollar-fifty or lose a dollar. This is the type of gamble that people often reject, owing to loss aversion, but the patients with lesions accepted the bets more than eighty per cent of the time, and they ended up making significantly more money than a control group made up of people who had no brain damage. “Clearly, having frontal damage undermines the over-all quality of decision-making,” Loewenstein, Camerer, and Drazen Prelec, a psychologist at M.I.T.’s Sloan School of Management, wrote in the March, 2005, issue of the Journal of Economic Literature. “But there are situations in which frontal damage can result in superior decisions.”
If we club the two studies together, one may come to a surprising conclusion that to become a good speculative investor or gambler you may need to temporarily knock out your parts of the brain involved in emotional decision making (one may use TMS here) and also additionally take a dopamine does to learn the rewarding strategies and actions early on. This may be the only way for us to counter the tyranny of loss aversion that nature has imposed on us and move towards that ideal of Homo Economicus.Sphere: Related Content
Nature Reviews Neuroscience has an interesting article that summarizes the latest findings about neurogenesis and synaptic plasticity in adult mice and how exposure to enriched environments and experience leads to later onset of diseases in transgenic mice models of human diseases like Huntington's disease, Alzheimer's disease and Parkinson's disease, fragile X and Down syndrome, as well as various forms of brain injury.
This is exciting news and lends credence to the fact that for full flowering and upkeep of your mental faculties, mental exercises and stimulating mental environment is a must.
Hat Tip : The Frontal Cortex
Tuesday, September 12, 2006
If you have always been interested in writing a book concerned with Cognitive Neuroscience, Psychology press is currently soliciting proposals for the same. More information at Cognitive Neuroscience Arena.
Please find below the detailed requirements
Contemporary Approaches in Cognitive Neuroscience
Psychology Press are launching a new series called "Contemporary Approaches in Cognitive Neuroscience".
* Stanislas Dehaene, Collège de France, Paris
* Alvaro Pascual-Leone, Harvard Medical School
* Jamie Ward, University College London
Invitation to Authors:
Reflecting contemporary and controversial issues in the study of cognitive neuroscience, the series aims to present a multi-disciplinary forum for cutting edge debate that will help shape this burgeoning discipline.
It offers leading figures in the field and the best new researchers an opportunity to showcase their own work, expand on their own theories and place these in the wider context of the field.
If you would like to submit a proposal to be included in this series we would like to hear from you! Titles in the series may be authored or edited; the only requirement is that each book must aim to make a contribution to a specific topic by reviewing and synthesising the existing research literature, by advancing theory in the area, or by some combination of these missions.
Please send your proposals to: email@example.com