john hawks weblog

paleoanthropology, genetics and evolution

mind

  • Whorfed

    Wed, 2009-06-17 18:30 -- John Hawks

    I found an interesting essay by Lera Boroditsky on Edge, titled, "How does our language shape the way we think?" She describes cross-cultural psychology experiments that test the ways that perception is affected by language differences.

    Even basic aspects of time perception can be affected by language. For example, English speakers prefer to talk about duration in terms of length (e.g., "That was a short talk," "The meeting didn't take long"), while Spanish and Greek speakers prefer to talk about time in terms of amount, relying more on words like "much" "big", and "little" rather than "short" and "long" Our research into such basic cognitive abilities as estimating duration shows that speakers of different languages differ in ways predicted by the patterns of metaphors in their language. (For example, when asked to estimate duration, English speakers are more likely to be confused by distance information, estimating that a line of greater length remains on the test screen for a longer period of time, whereas Greek speakers are more likely to be confused by amount, estimating that a container that is fuller remains longer on the screen.)

    I'd like to have seen more historical background -- the name Benjamin Lee Whorf isn't mentioned, for example -- and some more critical commentary on the negative evidence. But the positive examples are each interesting and help to show the subtle quality of the effects that today's psychologists mean when they talk about language influencing perception.

    Tags: 
    mind
    psychology
    language
    perception
    Sapir-Whorf effect

  • IQ, brain size and genetics in children

    Fri, 2008-12-05 15:01 -- John Hawks

    Dienekes points to a study by Marieke van Leeuwen and colleagues, in which they assess the phenotypic correlation between IQ and brain volume in a sample of 9-year-old children. The correlation overall is between 0.2 and 0.33 for different components of brain volume, consistent with earlier studies of adults based on MRI scanning.

    What interested me about the paper was the last sentence of the abstract:

    The relation between brain volume and intelligence was entirely explained by a common set of genes influencing both sets of phenotypes.

    which seems quite interesting if true. The paper involved a comparison of the phenotypic correlations in sets identical and fraternal twins, allowing an estimate of the genetic correlation of the traits.

    Table 7 shows the genetic and environmental correlations, below and above the diagonal, respectively. Amongst brain measures the genetic as well as the environmental correlations are significant, showing that correlations between genetic and environmental factors both contribute to the phenotypic correlations amongst the three brain measures. The same applies for the phenotypic correlations between PO [perceptual organization] and g [the general factor of IQ], and PO and VC [vocabulary and comprehension, another part of the IQ test]; common genetic as well environmental factors contribute to the phenotypic correlations between these intelligence measures.

    In other words, when it comes to the correlations within the different components of brain volume, and within different parts of the test battery, environmental correlations and genetic correlations were both important.

    In contrast, the phenotypic correlations between brain and intelligence measures and among intelligence measures are explained by correlations between genetic factors only.

    The different values for genetic correlations of test and brain volume variables gives them some ability to test one causal hypothesis:

    If intelligence causally influences brain volumes, this would also be reflected in the genetic and environmental correlations: all genetic and environmental factors that influence intelligence would, through the causal chain, influence brain volume. However, our study shows that only the genetic correlations are significant. In fact 85% to 100% of the covariation between brain volume and intelligence are caused by shared genetic factors. This leaves two options: 1) the relation between brain volume and intelligence is caused by a set of genes which influences variation in brain volume and this variation in turn leads to variation in intelligence 2) pleiotropy: there is a set of genes which influence brain volume as well as intelligence.

    The discarded hypothesis is, unfortunately, the least credible of the three alternatives anyway, unless you think that higher IQ actually inflates the volumes of people's brains.

    The paper could be more clear about the nature of the "common" genetic variants -- what it means is that the genes are held in common between the two phenotypes, not that they have found common genes. That leaves the nature of the actual genetics of the traits completely open (e.g., rare familial variants versus high-frequency variants, regulatory vs. coding, etc.). They do list a number of examples of possible genes (focusing on myelination as a process that might affect both phenotypes), but these are entirely speculative, and not really worth going into at this level.

    What is more interesting is the possibility that the genetic correlations mainly arise from early postnatal development:

    Possibly, these genetic factors come into play already early in development. Gale, O'Callaghan, Bredow, and Martyn (2006) and Gale, O'Callaghan, Godfrey, Law, and Martyn (2004) showed – measuring head circumference – that brain growth during infancy predicts intelligence in eight- and nine-years-olds, while brain size at birth and brain growth later in life is not associated with intelligence in both these age groups. After infancy children could not compensate for poor brain growth earlier in life. This shows that the relation between brain volume and intelligence already is established between birth and one year of age (van Leeuwen et al. 2008:8).

    This is worth further study since the initial postnatal brain growth period and rate have plausibly changed during human evolution. The timing and rate of developmental effects during this time (also very important to linguistic and other cognitive developments) could have been targets of selection in the past.

    Also, modularization (or demodularization) of these genetic networks might have influenced pleiotropies between the disadvantages of larger brains (in developmental and energetic terms) and the advantages of learning.

    References:

    van Leeuwen M, Peper JS, van den Berg SM, Brouwer RM, Hulshoff Pol HE, Kahn RS, Boomsma DI. 2008. A genetic analysis of brain volumes and IQ in children. Intelligence (in press) doi:10.1016/j.intell.2008.10.005

    Tags: 
    mind
    intelligence
    development
    behavior
    brain

  • H. M. dies after helping build the science of memory

    Fri, 2008-12-05 08:35 -- John Hawks

    A man known to most psychologists only as H. M. has died. Benedict Carey has the story. After a brain operation to relieve profound seizures, H. M. was left with a complete inability to form new declarative memories. And his condition led to a revolution in the science of memory itself:

    At the time, many scientists believed that memory was widely distributed throughout the brain and not dependent on any one neural organ or region. Brain lesions, either from surgery or accidents, altered people’s memory in ways that were not easily predictable. Even as Dr. Milner published her results, many researchers attributed H. M.’s deficits to other factors, like general trauma from his seizures or some unrecognized damage.

    “It was hard for people to believe that it was all due” to the excisions from the surgery, Dr. Milner said.

    That began to change in 1962, when Dr. Milner presented a landmark study in which she and H. M. demonstrated that a part of his memory was fully intact. In a series of trials, she had Mr. Molaison try to trace a line between two outlines of a five-point star, one inside the other, while watching his hand and the star in a mirror. The task is difficult for anyone to master at first.

    Every time H. M. performed the task, it struck him as an entirely new experience. He had no memory of doing it before. Yet with practice he became proficient. “At one point he said to me, after many of these trials, ‘Huh, this was easier than I thought it would be,’ ” Dr. Milner said.

    The implications were enormous. Scientists saw that there were at least two systems in the brain for creating new memories.

    Behavioral science depends so completely on the willingness of subjects to volunteer for analysis and study. But rarely has so much understanding been achieved upon the cooperation of a single person.

    Tags: 
    mind
    brain
    memory
    history of psychology

  • Terry Pratchett describes his Alzheimer's

    Tue, 2008-10-07 18:51 -- John Hawks

    I know many readers are fans of Terry Pratchett, as I am. He has a long, heartfelt article about his experiences with PCA, a type of early-onset Alzheimer's. An excerpt:

    When in Paradise Lost Milton’s Satan stood in the pit of hell and raged at heaven, he was merely a trifle miffed compared to how I felt that day. I felt totally alone, with the world receding from me in every direction and you could have used my anger to weld steel.

    Only my family and the fact I had fans in the medical profession, who gave me useful advice, got me through that moment. I feel very sorry for, and angry on behalf of, the people who don’t have the easy ride I had.

    Tags: 
    social
    mind
    disease

  • Darwin, emotion, and WALL-E

    Wed, 2008-07-16 10:36 -- John Hawks

    Jonah Lehrer went in to WALL-E (an enormously entertaining movie) and came out thinking of Darwin's Expression of Emotion in Man and Animals:

    The emotional brain is actually the most ancient part of our cortical machinery, a piece of hardware that's been refined by evolution over the last several hundred million years. That's why, as Darwin pointed out, animals that are utterly lacking in self-awareness - he called them "creatures of pure instinct" - tend to express their emotions in the same manner as humans. Even more radically, Darwin suggested that these expressions were evidence that the animals were also experiencing emotion, even though they were just obeying some ancient biological drives.

    Lehrer's recent book is Proust Was a Neuroscientist.

    Tags: 
    emotion
    behavior
    movies
    mind
    Darwin

  • Communication not language in the brain

    Wed, 2008-07-02 13:56 -- John Hawks

    Wired's Brandon Keim covers a new study by Susan Goldin-Meadow, which shows a conflict between linguistic and gestural communication strategies:

    "This may reflect the real thought that comes before language," said study co-author Susan Goldin-Meadow, a University of Chicago psychologist. "It seems pretty natural."

    Goldin-Meadow's team asked forty people -- ten speakers apiece of English, Mandarin Chinese and Spanish, each of which follows the SVO order, and ten speakers of Turkish, which follows an SOV order -- to describe a series of simple actions, such as a girl turning a knob, with gestures.

    Regardless of their native language, the subjects almost universally preceded object with verb: girl knob turns.
    "We expected that the language they spoke would influence the language of their gestures, but it didn't," said Goldin-Meadow.

    They propose the "meaning" of the study is that the gestural strategy here reflects the actual structure of symbolic communication in the brain. In that view, the linguistic version is a language-specific translation of the brain's version.

    Tags: 
    communication
    mind
    language

  • Theory of Mind does not require episodic memory?

    Sat, 2007-11-24 22:57 -- John Hawks

    The ability to interpret others' mental states and intentions, called "Theory of Mind," has been a key area of interest for those studying the evolution of primate and human social behavior. Often, people have imagined that Theory of Mind emerges as a correlate of self-awareness -- the ability to reflect on one's own mental states. As the model goes, a focal individual interprets another's mental state by imagining herself "in the shoes of" the other individual.

    Well, this week's Science has a short paper by R. Shayna Rosenbaum and colleagues that presents evidence that the "in their shoes" model is wrong. First a mini-review of why you would believe the usual idea in the first place:

    The idea that ToM is closely related to, and that it may depend on, episodic memory and autonoetic consciousness seems perfectly natural: that in order to imagine and make sense of other people's thoughts, feelings, intentions, and actions, we must rely on our autobiographical recollections (1). The ability to consciously recollect past personal happenings has been shown to be necessary for imagining coherent and detailed personal happenings in the future (2, 3). Both episodic memory and ToM emerge close in time in ontogenetic development (4). The neural substrate on which the two abilities rely is in many ways strikingly similar (1).

    But they examined two patients with brain injuries that eliminated personal episodic memory. In both cases, the patients showed an ability to interpret the mental states of other individuals, even though they could not imagine future events in their own perspective:

    The current findings are at variance with the idea that the ability to simulate or reconstruct one's own past mental states is necessary to imagine the contents of other people's minds (1, 2). Both K. C. and M. L. suffer from severe difficulties in consciously (autonoetically) recollecting any events from any period of their lives. Yet they have no apparent difficulty in taking other persons' perspectives and inferring other people's thoughts, feelings, and intentions, as revealed by the ToM tests. The findings imply that K. C.'s and M. L.'s ToM ability may depend on semantic memory and general knowledge abilities that are largely preserved in both cases (5, 6).

    This may go along with last week's paper by Hamlin, Wynn and Bloom, which showed that infants develop an ability to evaluate others' intentions much earlier than had been thought:

    Here we show that 6- and 10-month-old infants take into account an individual's actions towards others in evaluating that individual as appealing or aversive: infants prefer an individual who helps another to one who hinders another, prefer a helping individual to a neutral individual, and prefer a neutral individual to a hindering individual. These findings constitute evidence that preverbal infants assess individuals on the basis of their behaviour towards others.

    This isn't quite the same as Theory of Mind -- the infants are getting a general idea of whether a person is nice, not evaluating specific intentions. But the study of the individuals who lack episodic memory suggested that they were using more general cognitive resources to enable their interpretation of others' intentions. That would presumably include the kinds of heuristics that these babies were developing to judge people as "helpers" or "hinderers".

    It may be that Theory of Mind is built from exactly the kind of simple observations that the babies can use, and that rather than build a detailed "simulacrum" of another person's intentions, we can interpret their likely intentions based on general knowledge of what people are likely to do based on similar external signs. That kind of skill might vary quantitatively among primate species, and provides a possible evolutionary pathway for this important social ability.

    References:

    Hamlin JK, Wynn K, Bloom P. 2007. Social evaluation by preverbal infants. Nature 450:557-559. doi:10.1038/nature06288

    Rosenbaum RS, Stuss DT, Levine B, Tulving E. 2007. Theory of mind is independent of episodic memory. Science 318:1257. doi:10.1126/science.1148763

    Tags: 
    mind

  • Mind control

    Tue, 2007-08-21 15:20 -- John Hawks

    We've been watching this show on the SciFi channel, Mind Control, in which British "psychological illusionist" Derren Brown. Brown is sort of like a much less skeevy Criss Angel. Not that much less skeevy -- Brown is best-known for playing Russian roulette on TV. And like every aspiring mentalist, he's mastered that eyes-focused-somewhere-inside-your-skin look.

    To tell you the truth, the show comes on after Flash Gordon, and, well, I'm a committed Flash Gordon nut.

    Anyway, the beauty of the show is that Brown lets you in on the trick, at least some of the time, since the "trick" is really just the power of suggestion. With a highly rehearsed script including repeated cues, he can make people forget what they were thinking before, and to think what he wants instead.

    I'm totally going to try this on my classes! Look out, students. Especially on evaluation day....

    So in today's science section, the NY Times has a story by George Johnson, who got to sit in on Magic Day at the Consciousness meetings. It sounds pretty cool:

    After two days of presentations by scientists and philosophers speculating on how the mind construes, and misconstrues, reality, we were hearing from the pros: James (The Amazing) Randi, Johnny Thompson (The Great Tomsoni), Mac King and Teller -- magicians who had intuitively mastered some of the lessons being learned in the laboratory about the limits of cognition and attention.

    "This wasn't just a group of world-class performers," said Susana Martinez-Conde, a scientist at the Barrow Neurological Institute in Phoenix who studies optical illusions and what they say about the brain. "They were hand-picked because of their specific interest in the cognitive principles underlying the magic."

    Page 2 of the story gums its way into the confusing topic of qualia. Now, Qualia Day in my biology of mind course would be a good one to try out the mind control -- that is, on the students who really can't be convinced that philosophy is fun.

    This is a problem that's big and little at the same time -- from a certain perspective, nothing seems more central than qualia, and yet that centrality seems to have no observable effect on anything else. It's hard to avoid though -- because if you're going to discuss the mind from an evolutionary perspective, you have to lay out what kinds of things evolutionary biology is well-placed to explain. "Qualia" are among the few things that aren't (necessarily) on that list.

    So stick to the front page if you're not interested -- and the last half of page 3, where the Amazing Randi gets a few words:

    "Allow people to make assumptions and they will come away absolutely convinced that assumption was correct and that it represents fact," Mr. Randi said. "It's not necessarily so."

    That's one of the reasons we used to love Jonathan Creek -- at least, until they got rid of Maddie. If your perception can be snookered by assumptions, then your logic can easily go with it.

    The beauty of magic is that you know it's not possible, and yet your senses believe it anyway.

    [Teller] left us with his definition of magic: "The theatrical linking of a cause with an effect that has no basis in physical reality, but that -- in our hearts -- ought to."

    What's more amazing? That these scientists got a show from some of the best non-skeevy magicians in Vegas? Or that Teller talks?

    Tags: 
    meetings
    consciousness
    mind

  • Same as it ever was

    Mon, 2007-07-23 13:18 -- John Hawks

    A couple of months ago, Seed magazine ran a conversation between singer/songwriter David Byrne (of the Talking Heads) and cognitive music researcher Daniel Levitin. It's a really interesting mix of topics, and reading David Byrne's thoughts on ideas like mirror neurons and exaptation is pretty remarkable.

    DB: So when you watch a performance, sports for example, you're not only watching somebody else do it. In a neurological kind of way, you're experiencing it.

    DL:Yeah, exactly. And when you see a musician, especially if you're a musician yourself--

    DB: --air guitar.

    DL: Air guitar, right! And you can't turn it off -- it's without your conscious awareness. So mirror neurons seem to have played a very important role in the evolution of the species because we can learn by watching, rather than having to actually figure it out step-by-step.

    I noticed that Levitin seemed to be doing more and more of the talking as the conversation went on, but he makes it a good introduction to some current thinking on the evolution of musical ability and cognition.

    Tags: 
    mind
  • Sun, 2007-07-08 11:57 -- John Hawks

    The Sunday NY Times is carrying a very long article about Williams syndrome by David Dobbs. I think it's a nice article, beginning with some anecdotes relating the lives of people with Williams, and then proceeding into the science:

    After being ignored for almost three decades, Williams has recently become one of the most energetically researched neurodevelopmental disability after autism, and it is producing more compelling insights. Autism, for starters, is a highly diverse “spectrum disorder” with ill-defined borders, no identified mechanism and no clearly delineated genetic basis. Williams, in contrast, arises from a known genetic cause and produces a predictable set of traits and behaviors. It is “an experiment of nature,” as the title of one paper puts it, perfect for studying not just how genes create intelligence and sociability but also how our powers of thought combine with our desire to bond to create complex social behavior — a huge arena of interaction that largely determines our fates.

    Also, the story of J. C. P. Williams himself presents an unsolved mystery:

    Williams syndrome was first identified in 1961 by Dr. J. C. P. Williams of New Zealand. Williams, a cardiologist at Greenlane Hospital in Auckland, noticed that a number of the hospital’s young cardiac patients were small in stature, had elfin facial features and seemed friendly but in some ways were mentally slow. His published delineation of this syndrome put Dr. Williams on the map — off which he promptly and mysteriously fell. Twice offered a position at the prestigious Mayo Clinic in Rochester, Minn., he twice failed to show, disappearing the second time, in the late ’60s, from London, his last known location, with the only trace an unclaimed suitcase later found in a luggage office.

    Wow, that's weird. I couldn't find any more details on the disappearance.

    Tags: 
    mind

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