The Psychological & Neuroscientific musings of sandygautam
sandygautam
Sandeep Gautam is a psychology and cognitive neuroscience enthusiast, whose basic grounding is in computer science.
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Posts by sandygautam
The way the worm wiggles
Mar 11th
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Once in a while you come across a study article that is so elegant and lucid that you have to blog about it. A not-son recent, but new to me article in PLOS computational biology by Stephens et al is just such an awesome and well written article that despite being outside my comfort zone and expertise area I feel driven to write about it and bring it forth to a wider audience(which it rightfully deserves).
The article reduces the spontaneous motion and shapes thereof of nematode worm on an agar plate to low dimensionality and finds using principal component analysis (PCA) and eignevectors approach , that four factors (eigenvectors or eigenworms as the authors call them) were sufficient to describe the spontaneous motion/ shape of the nematode worm C elegans, These four dimensions were able to account for 95 % of the variance in the shape of the worm.
The authors measured the curvature of the worm as it moved on the agar plate and found that the actual shape at any instant can be easily represented by projections along the four dimensions/eigenworms and that these were sufficient and no higher dimension representation were needed.
The first two modes or eigenworms were sinuous in nature and were related to a traveling wave down the worms body. The speed of phase change was related to the speed of the forward/backward ,motion of the worm.
The third eigneworm was related to the turning behavior of the worm while the fourth eigneworm was related to teh fact that the head and tail of the worm can move independently and thus there was a small effect at the head and tail region of the fourth mode/eigenworm.
This decomposition of shape and spontaneous movement was what I found most attractive and understandable. they later found that there were attractor state in the seemingly chaotic worm motion and that if the external stimuli (thermal stimuli having no directionality) was applied to the worm when it was in a proper state then it can cause it to turn in a predictable direction. they were thus , with the help of thermal stimuli, able to ’steer’ the worm.
To me this is one of best exemplars of how difficult to understand scientific concepts can be easily explained to lay audiences using a combination fo great text and equally great accompanying figures. The article was published in open access PLOS so rush over and have a look yourself.
Stephens, G., Johnson-Kerner, B., Bialek, W., & Ryu, W. (2008). Dimensionality and Dynamics in the Behavior of C. elegans PLoS Computational Biology, 4 (4) DOI: 10.1371/journal.pcbi.1000028
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Mar 9th
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Chronically stressful life events have been shown to lead to depression. Chronic stress leads to hyperactivity of HPA axis leading to more glucocorticoids (cortisol) in the human body. This excess cortisol in term is proposed to underlie the affective symptoms of depression. Also, depressive people have been found to have up to 20% smaller hippocampal volume, and a recent theory is gaining ground that depression is due to reduced neurogenesis. Even if the entire spectrum of depressive symptoms is not due to reduced neurogenesis and atrophied or smaller hippocampus, at least the cognitive symptoms of depression are largely due to this.
I stumbled upon a commentary by Robert Sapolsky that although is 10 years old, but I still found interesting and worth bringing to notice of my dear readers. In it Sapolsky looks at a study by Czeh et al that found evidence linking reduced proliferation in dentate gyrus and a shrunken hippocampus to depressive stress as modeled by psycho-social stress paradigm in tree shrew. Also, they found that an antidepressant, tianeptine, reversed the effects of stress by restoring proliferation and hippocampus size and thus reversing symptoms of depression. However the level of glucorticiods were still higher, after anti-depressant treatment, and thus it is apparent that anti-depressants work downstream of stress induced increase in glucorticoids. Sapolsky believes that the data support either of models presented in figure 1A or figure 1B i.e. the increased glucocrticoids can lead to shrinkage of hippocampus directly or through their effect on affective symptoms. I believe figure 1C is also possible and its not necessarily incompatible with 1A or 1B and that increased stress may lead to increased cortisol- may lead to reduced neurogenesis may lead to shrinkage of hippocampus and which may in turn lead to affective and cognitive symptoms.
An alternative to reduced neurogenesis/ proliferation theory is the dendritic atrophy/ neurotoxicity theory that posits that shrinkage of hippocampus is due to cell death/ white matter loss. This again is a possibility but the evidence in favor of reduced neurogenesis is growing and becoming strong by the day.
Overall the new paradigms in depression research that look beyond serotonin or mono amine imbalance is a welcome trend and hopefully would lead to better interventions and prevention strategies and not just better pharmaceutical innovations. Its time one realized the rile chronic stress play sin depression and how that can be easily prevented to reduce the mental health burden.
Sapolsky, R. (2001). Depression, antidepressants, and the shrinking hippocampus Proceedings of the National Academy of Sciences, 98 (22), 12320-12322 DOI: 10.1073/pnas.231475998 Czeh, B. (2001). Stress-induced changes in cerebral metabolites, hippocampal volume, and cell proliferation are prevented by antidepressant treatment with tianeptine Proceedings of the National Academy of Sciences, 98 (22), 12796-12801 DOI: 10.1073/pnas.211427898
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Mar 7th
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We normally view happiness and sadness to be opposites on a single continuum, but I propose that it is time to change the textbooks and view happiness as opposed to ennui/despair and sadness as opposed to anger/irritability when it comes to basic opponent affects.
But before we go down that path first a detour.
I recently read Flourishing: edited by Keyes & Haidt , and the last article by Keyes caught my attention. I looked up a few more articles by Keyes and found this one that again elaborates on the theory put forward in the book chapter.
The point Keyes wants to make is that mental illness and mental health are two different things and are relatively independent of each other. Traditionally mental health has been conceptualized as the absence of mental illness, but Keyes says that our intuitions are incorrect here and mental health is another, parallel continuum on which people can differ.
Throughout human history, there have been three conceptions of health.The pathogenic approach is the first, most historically dominant vision, derived from the Greek word pathos, meaning suffering or an emotion evoking sympathy. The pathogenic approach views health as the absence of disability, disease, and premature death. The second approach is the salutogenic approach, which can be found in early Greek writings and was popularized by Antonovsky (1979) and humanistic scholarship (e.g., Carl Rogers and Abraham Maslow). Derived from the word salus, meaning health, the salutogenic approach views health as the presence of positive states of human capacities and functioning in thinking, feeling, and behavior (Stru¨mpfer, 1995). The third approach is the complete state model, which derives from the ancient word for health as being hale, meaning whole and strong. This approach is exemplified in the World Health Organization’s (1948) definition of overall health as a complete state, consisting of the presence of a positive state of human capacities and functioning as well as the absence of disease or infirmity. By subsuming the pathogenic and salutogenic paradigms, the whole states approach is, in my opinion, the only paradigm that can achieve true population health.
Thus when we talk of whole states mental health we are basically talking about two related things- a mental illness or disability dimension and a flourishing or mental health dimension. Keyes et al have performed confirmatory factor analysis on measure used to measure mental health and illness and found that the data is best explained by two latent factors-one related to flourishing and the other to illness.
This is how they define mental health or flourishing dimension.
Until recently, mental health remained undefined, unmeasured, and therefore unrecognized at the level of governments and nongovernmental organizations. In 1999, the Surgeon General, then David Satcher, conceived of mental health as “a state of successful performance of mental function, resulting in productive activities, fulfilling relationships with people, and the ability to adapt to change and to cope with adversity” (U.S. Public Health Service, 1999, p. 4). In 2004, the World Health Organization published a historic first report on mental health promotion, conceptualizing mental health as not merely the absence of mental illness but the presence of “a state of well-being in which the individual realizes his or her own abilities, can cope with the normal stresses of life, can work productively and fruitfully, and is able to make a contribution to his or her community” (World Health Organization, 2004, p. 12).
Keyes comes up with 13 symptoms of mental health and these include Positive emotions (i.e., emotional well-being) including positive affect and avowed quality of life; Positive psychological functioning (i.e., psychological well-being) consisting of self-acceptance, positive relations with others, personal growth, purpose in life, environmental mastery, and autonomy (see Keyes & Ryff, 1999); and Positive social functioning (i.e., social well-being) consisting of social coherence, social actualization, social integration, social acceptance, and social contribution. In DSM style they propose that individuals exhibit some minimum symptoms to classify as flourishing and those with very low scores be classified as languishing.
To be diagnosed as flourishing in life, individuals must exhibit high levels on at least one measure of hedonic well-being and high levels on at least six measures of positive functioning. Individuals who exhibit low levels on at least one measure of hedonic well-being and low levels on at least six measures of positive functioning are diagnosed as languishing in life. Adults who are moderately mentally healthy do not fit the criteria for either flourishing or languishing in life.
Keyes then goes on to show the costs of languishing and not focusing on mental health and why a narrow focus on cure/prevention of mental illness is detrimental, but that is beside the point as to today’s topic. what is most important take way for today is that there are two separate factors of mental health and mental illness.
This brings us back to the affects- happiness, sadness, ennui/despair and anger/irritability. Consider for a moment depression. It is an illness characterized by sad mood and anhedonia etc. Consider its counterpart on the illness spectrum. while a normal person not having depression may seem the counterpart, the real counterpart is mania which often has a angry/irritable mood (alongside euphoria) associated with it. Also depression is characterized as a reaction to losses/continuous exposure to stresses that makes goals out of reach/unachievable. Here the focus is preventive in nature- the state does not deteriorate further and goals do not remain unmet. However, depression or sad mood is also an avoidance reaction. One becomes withdrawn from the situation and does not fight the stress, but flights from the stress by withdrawing in a cocoon. The loss of appetite and more sleep can be seen as behavioral counterparts of withdrawing or exhibiting a flight response to stress.
As opposed to this, mania can be seen behaviorally as an active approach state in which one works actively towards the things required to overcome the loss of valued entity/life goal. Again, I propose that mania is a reaction to a situation similar to depression – when something is lost/ is under threat of losing- but this time , under stress, one fights and not flights- thus one becomes energized to right the wrong and may become angry/ irritable if the efforts to retain goals/ valued entities are frustrated by external world. It is important that both mania and depression are on the illness scale of functioning/ mental health and are a result of life trauma/ stress/ perceived/ real/ threat of loss of loved object/person. Thus the focus is preventive and the state is of scarcity.
Contrast this to a state of abundance when ones (life) goals have been met/ are within reach.// This apparent positive state of affairs may again give rise to different emotions/ behavioral manifestations depending on whether one has approach or avoidance dominant reaction. If one approaches the more free time available after goal accomplishment as a boon that can be used to home ones hobbies/find other meaning in life/ build relationships etc and not as a threat ( free time can be a threat) then one experiences positive emotion of happiness and behaviorally flourishes.
In contrast consider a similar person who has achieved everything in life – (a good job, wife, kids etc ) , but given the fact that one is living in abundance is frightened or flights from the free time that has been made available. that person will be listless, will exhibit ennui or boredom and may even exhibit despair as he finds life meaningless. Thus behaviorally he would languish.
Thus, I rest my case that happiness is opposed to ennui/despair while sadness is opposed to anger/irritability and while happiness is a measure of flourishing; sadness is a measure of illness. One can definitely conduct experiments , perform factor analysis to confirm, that indeed happiness and sadness is not a unitary construct, but are two separate but related dimensions. I would love to hear your comments.
Keyes, C. (2007). Promoting and protecting mental health as flourishing: A complementary strategy for improving national mental health. American Psychologist, 62 (2), 95-108 DOI: 10.1037/0003-066X.62.2.95
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Mar 5th
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Happiness may lead to mood-congruent effects of increasing trust(a positive emotion itself) in interpersonal situations; an alternative theory is that happiness leads to top-down processing , thus relying more on activated schema , stereotypes etc and thus leading to more trust when trust schema or cues are salient and distrust when untrustworthy schema / cues are active.
As per the mood-congruent theory of effect of happiness, surmised that happy people would be more trusting and there would be a main effect of happiness manipulation on trust in experimental settings. As per the assimilation-accommodation theory, viz that happiness leads to assimilation or use of existing constructs (stereotype./ schema etc) while sadness leads to accommodation or bottom-up processing whereby new constructs may be created, the conjecture is that happy people will show trust in trust situations and distrust in distrust situations and thus there would be an interaction effect in 2 (happiness/ neutral mood) x 2 (trust/distrust situation, stereotype or cue) study design.
These above two are competing hypothesis that make measurable and clearly different and distinguishable predictions and can be easily experimentally verified.
Robert Lount, Jr. set out to investigate precisely this piece of puzzle and his data supported the thesis that there is an interaction effect of mood on trust cues and thus happy people are more gullible when trust cues/stereotypes are active; and also more paranoid or distrusting when distrust cues/ schema are active.
He performed a total of 5 different experiments to cement his thesis.
- The first experiment relied on film clips to induce mood and dictator game to measure trust. Trustworthiness of the other party was manipulated by interpersonal vs inter group situation. As per a theoretical framework, by default in interpersonal interactions (say trust games) the other individuals believed to be trustworthy. In contrast in an inter-group interaction, in-group vs out-group psychology comes into play and the other group as a whole is believed to be inherently untrustworthy. thus, in the first experiment they used interpersonal or inter-group conditions to manipulate trustworthiness cues and found the interaction effect of happiness and trust cues as hypothesized.
- The second experiment was carried out to ascertain that it is indeed distrust in inter-group condition that is in play and leads to happy people showing distrust in distrust salient conditions. The paradigm used was modified prisoners dilemma in this case.
- The third experiment did not use ingroup-outgroup factors but instead provided explicit information about the trustworthiness of a person and then measured the effect of mood on trust using the dictator game and found the same interaction effect of mood and trust cues as opposed to a direct main effect of affect on trust.
- The fourth experiment used subtle implicit measures of trustworthiness/ untrustworthiness by utilizing computer generated facial features and used explicit measures of trust like rating the person as trustworthy when subjects mood had been manipulated. Again the interaction effect was observed.
- The fifth and final experiment was performed to clarify that it is indeed the underlying activation of schema/ stereotype that is in play when happy people become gullible/ paranoid in presence of cues; and this was done by showing that normal people too , under cognitive load conditions, when they are known to rely on stereotypes/ schema, show the same interaction effects on trust.
Here are the conclusions from the study:
The results in this article are consistent with work demonstrating that a positive mood increases reliance upon stereotypes (Bless, Schwarz, & Wieland, 1996; Bodenhausen et al., 1994; Park & Banaji, 2000) and scripts in interdependent situations (Hertel et al., 2000). More pointedly, the findings from all five experiments supported the predictions of the accommodation–assimilation model (see Bless & Fiedler, 2006; Fiedler, 2001b, for reviews) over mood-congruency models. This leads to a fairly strong conclusion that the relationship between positive mood and trust depends, in large part, on available schemas, cues, and stereotypes.
To me the evidence is as good as it needs to be. It also fits in my broader context of seeing good/happy mood as a precursor to mania whereby happiness leads to use of stereotypes/schema , leads to becoming more gullible/ paranoid / leading to psychoses. although the present study did not had anything to say about sad mood (the contrast was with neutral mood) it is not unreasonable to extrapolate and claim that sad people are more realistic and depend on behavior of the other party rather than stereotypes to ascertain in whom to place their trust. this too fits in the broader scheme of things where sad mood is a precursor to depression which has been shown to make people more realistic. If there is an upside to depression, the only one may be that it makes us more realistic/ rational.
Lount, R. (2010). The impact of positive mood on trust in interpersonal and intergroup interactions. Journal of Personality and Social Psychology, 98 (3), 420-433 DOI: 10.1037/a0017344
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Mar 5th
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Happiness and sadness have different effects on verbal behavior. Happiness may either lead to shallow happy-go-lucky, small talk moments or more profound and deep interactions that are meaningful and fulfilling. Sadness similarly may facilitate deep philosophical ruminations and conversations or lead to shallow and trivial small talk. Which of these is the actual scenario is not intuitive, but new research by Mehl et al has come to our rescue and provides a definitive answer.
Meh et al used the Electronically activated recorder (EAR) which is a device that unobtrusively records 30 s snippets of conversation at random times of the day as the subjects as they go about their daily life. As such it is a better measure than experience sampling method (ESM) which is intrusive and relies on self reports.
The coders than analyzed and coded the snippets of conversations as captured using EAR into small talk versus substantive conversations. Also the number of time spent in conversations and socially versus time spent alone was also calculated for the subjects.
The subjects filled self-report satisfaction with life survey as well as other happiness measures which were used to calculate the well being/happiness index for the subjects.
The results were clear. Happy people spent more time talking to others in social settings versus spending time alone. further, happy people spent much more time in substantive conversations than in making samll talk. this was revers in the case of sad people.
However, the authors caution, and I believe it is a reasonable rider. that this study is correlational and does not elucidate the direction of causality. It may be the case that happy people have more substantive conversations to make or t may be the case that just as self-disclosure leads to intimacy having deep and meaningful conversations leads to happiness.
The full text is available for free online and is written in a very lucid manner and I recommend reading it in full. I am including a snippet to whet the appetite.
Together, the present findings demonstrate that the happy life is social rather than solitary, and conversationally deep rather than superficial. What makes these findings especially compelling is the lack of method overlap between the well-being measures (self- and informant reports) and the interaction measures (direct observation). Also, the replication of findings across measures of well-being and across weekday and weekend behavior is encouraging. Naturally, our correlational findings are causally ambiguous. On the one hand, well-being may be causally antecedent to having substantive interactions; happy people may be “social attractors” who facilitate deep social encounters (Lucas & Dyrenforth, 2006). On the other hand, deep conversations may actually make people happier. Just as self-disclosure can instill a sense of intimacy in a relationship, deep conversations may instill a sense of meaning in the interaction partners. Therefore, our results raise the interesting possibility that happiness can be increased by facilitating substantive conversations (Sheldon & Lyubomirsky, 2006). Future research should examine this possibility experimentally. Remarking on Socrates’ dictum that “the unexamined life is not worth living,” Dennett (1984) wrote, “The overly examined life is nothing to write home about either” (p. 87). Although we hesitate to enter such delicate philosophical disputes, our findings suggest that people find their lives more worth living when examined?at least when examined together.
Indeed, a life examined together and being more social/ loquacious and deep is definitely more happy and worth living.
Mehl, M., Vazire, S., Holleran, S., & Clark, C. (2010). Eavesdropping on Happiness: Well-Being Is Related to Having Less Small Talk and More Substantive Conversations Psychological Science DOI: 10.1177/0956797610362675
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