john hawks weblog

paleoanthropology, genetics and evolution

cognition

  • Monkey numerical distractions

    Fri, 2011-04-15 08:20 -- John Hawks

    This study has been out for a few weeks, and I've been meaning to put up a short comment about it: "Representational format determines numerical competence in monkeys", by Vanessa Schmitt and Julia Fischer [1]. The abstract:

    A range of animal species possess an evolutionarily ancient system for representing number, which provides the foundation for simple arithmetical operations such as addition and numerical comparisons. Surprisingly, non-human primates tested in ecologically, highly valid quantity discrimination tasks using edible items often show a relatively low performance, suggesting that stimulus salience interferes with rational decision making. Here we show that quantity discrimination was indeed significantly enhanced when monkeys were tested with inedible items compared with food items (84 versus 69% correct). More importantly, when monkeys were tested with food, but rewarded with other food items, the accuracy was equally high (86%). The results indicate that the internal representation of the stimuli, not their physical quality, determined performance. Reward replacement apparently facilitated representation of the food items as signifiers for other foods, which in turn supported a higher acuity in decision making.

    This seems so obvious in retrospect. An experimenter has to provide some kind of motivation or there will be no experiment. Providing food rewards in psychology tests on animals will conflate numerical cognition with food, rewards, and motivation. I'm surprised that a simple substitution of inedible items turned out to be so successful in relaxing this cognitive bias.

    As I'm thinking about the "numbers as technology" theme, I keep returning to the idea that most interesting technologies are cobbled together from heterogeneous parts. Cognitive technology is no exception. In this experiment, we see the interference between the food/reward aspects of cognition and the representation of number. To have an effective practice of number as applied to food items, an individual would have to overcome this interference.

    We might tinker with the system in different ways -- for example, we could set up a new system of behavioral rewards or we could change neurotransmitter regulation to decrease food salience. What is the dividing line between technical and natural solutions? Imagine a pill that improves monkey math by inhibiting dopamine receptors. The same inhibition might emerge by mutations to dopamine receptors -- a natural tweak that alters the threshold of technical interventions. A new reward system might seem purely technical -- in the experiment, it worked to substitute different kinds of food treats in different contexts. But then, "different" is itself a function of perception, which can be changed by changing visual and olfactory receptors. "Technical" is a matter of arranging heterogeneous things in such a way that their natural course of action achieves a desired end.


    References

  • Joshua Foer's memory racket

    Sun, 2011-04-03 11:12 -- John Hawks

    For Sunday morning (here in California, still, although it's fading into afternoon in my native land), I can point you to a book excerpt by Joshua Foer, from his new book, Moonwalking with Einstein: The Art and Science of Remembering Everything. Foer describes in detail how he set about to master the method of loci, to see just how hard it can be to compete in elite memory competitions. The number part was interesting:

    When it comes to memorising long strings of numbers, such as 100,000 digits of pi, most mental athletes use a more complex technique that is known as "person-action-object", or PAO. In the PAO system, every two-digit number from 00 to 99 is represented by a single image of a person performing an action on an object. The number 34 might be Frank Sinatra (a person) crooning (an action) into a microphone (an object). Unlike the Major System, these associations are entirely arbitrary and have to be learned in advance, which is to say it takes a lot of remembering just to be able to remember.

    I've always thought of paleoanthropology as an extreme memory competition...

  • The mystery of left lateralization

    Wed, 2011-03-09 09:22 -- John Hawks

    This morning, a timely post by cognitive neuroscientist Sophie Scott addresses the localization of language functions on the left side of the brain:

    The elephant in the room is why linguistic representations and processes are so associated with the brain’s left hemisphere in the first place. The left lateralisation of language is seen in 96 per cent of right-handed people, and is still there in 73 per cent of left-handed people (Knecht et al, 2000). It is there for men and women equally. People whose language centres are not in their left hemisphere have it in their right hemisphere: there is no evidence for people who have an intermediate, more equally divided representation of language across the left and right sides of the brain. And if the language-dominant hemisphere is damaged, the non-dominant hemisphere can take over function. Does this mean that the non-dominant hemisphere still performs linguistic functions in some low-key way? Or that it can adapt following damage to the brain (or perhaps even that it is released from some form of suppression)?

    I discussed this to some extent last week ("Language bootstrapping the brain"), but it's worth re-emphasizing: the great plasticity of language localization is really not very compatible with the hypothesis of a "language organ", except in the sense that an "organ" might self-organize upon input from the environment. It's a bit like saying the spleen could spontaneously take on some of the functions of the kidneys, in the right environment.

  • Number as cognitive technology

    Tue, 2011-03-08 21:00 -- John Hawks

    Archaeologists often define technology in terms of material products. People make stuff, and that stuff is technology.

    But there's another way to think about the stuff we make: in terms of the information we need to make it. Technology is know-how, it's skill. It's something we learn how to do. Manufacturing may have physical side effects, but it's the cognitive software that lies at the heart of technology.

    This usage is true to the etymology of the word, "technology":

    from Gk. tekhno-, combining form of tekhne "art, skill, craft, method, system," probably from PIE base *tek- "shape, make" (cf. Skt. taksan "carpenter," L. texere "to weave;" see texture).

    I mention this because, if we take this perspective on technology, then some "technology" may never be instantiated in material -- it may reside purely in the mind. That is the contention that Michael Frank and colleagues made in a 2008 paper about speakers of a language that does not have cardinal numbers above two [1]. Frank and colleagues set out to find whether this curious lack of number words causes Pirahã speakers to deal with numbers in experimental contexts differently from speakers of other languages.

    The results showed that Pirahã speakers could complete number matching tasks, using strategies that were also widespread among non-Pirahã speakers in other contexts.

    A total lack of exact quantity language did not prevent the Pirahã from accurately performing a task which relied on the exact numerical equivalence of large sets. This evidence argues against the strong Whorfian claim that language for number creates the concept of exact quantity (and correspondingly, that without language for number, any task requiring an exact match would be impossible). Instead, the case of Pirahã suggests that languages that can express large, exact cardinalities have a more modest effect on the cognition of their speakers: They allow the speakers to remember and compare information about cardinalities accurately across space, time, and changes in modality. Visual and auditory short-term memory are highly limited in their capacity and temporal extent (Baddeley, 1987). However, the use of a discrete, symbolic encoding to represent complex and noisy perceptual stimuli allows speakers to remember or align quantity information with much higher accuracy than they can by using their sensory short-term memory. Thus, numbers may be better thought of as an invention: A cognitive technology for representing, storing, and manipulating the exact cardinalities of sets.

    At the moment, my twins are making great strides in math, at least compared to their skills six months ago. Then, their mastery of number depended on counting objects, which they tracked using fingers and toes. When they got to higher numbers, they would carry out operations by envisioning imaginary fingers and toes in their heads. Now, they have learned several different strategies to break up numbers and regroup or double them, allowing them to easily add and subtract two-digit numbers.

    It's pretty cool to see it unfold, but it's essentially based on learning a technology of number. Numbers can be patterned to accomplish addition and subtraction in many ways, and with some practice and memorization, kids can attain a very rapid pace of solving problems. It's something that most of us have in their schooling somewhere, and there's nothing magical about it -- we just have to learn some algorithms and practice them.

    The Pirahã are different from speakers of other languages with more cardinal numbers, because they do not have that particular shorthand. It's a significant aid to number processing, because words and concepts provide ways to escape the limits on human short-term memory. Frank and colleagues connect this research on number to other aspects of language and cognition:

    Where does this leave the Whorf hypothesis, the claim that speakers of different languages see the world in radically different ways? Our results do not support the strongest Whorfian claim. However, they are consistent with several recent results in the domains of color ([Gilbert et al., 2006], [Uchikawa and Shinoda, 1996] and [Winawer et al., 2007]) and navigation (Hermer-Vazquez, Spelke, & Katsnelson, 1999). In each of these domains, language appears to add a second, preferred route for encoding and processing information. In the case of color, language enables faster performance in search, better discrimination, and better memory when target colors can be distinguished from distractors by a term in the participant’s language. However, verbal interference – which presumably blocks access to linguistic routes for encoding – eliminates this gain in performance, suggesting that the underlying perceptual representations remain unmodified. Likewise in the case of navigation: The use of particular linguistic devices allows (though does not require, see e.g., Li & Gleitman, 2002) efficient compressive navigational strategies. But again, under verbal interference these strategies are not accessible and participants navigate using strategies available to infants and non-human animals.

    I would have written more subtle things about the Whorf hypothesis, and maybe I will some other time.

    I very much like the idea that language itself provides the gears of a cognitive technology -- I think that is a very powerful one that we should apply more broadly in the past. It is misleading to see minimal stone tools, or the organic tools of other primates, as the simplest basis of technology. Technology begins with habits of mind, developed as strategies to better process regularities in the social environment. The powerful thing about language is that it gets in from outside. Children encounter regularities that have already taken hold in experienced minds. As I discussed last week ("Language bootstrapping the brain"), the process of language learning can proceed surprisingly well within brains with very different structural equipment.

    One other observation of interest: Color and number words were "technologies" that were acquired surprisingly well by Alex the grey parrot. Talk about a very different kind of brain!


    References

  • Hauser update

    Thu, 2010-08-19 10:17 -- John Hawks

    The Chronicle of Higher Education reports on an "internal document" from the Marc Hauser investigation: "Document Sheds Light on Investigation at Harvard". The Chronicle story begins by detailing how discrepancies in coding monkey behavioral responses first came to light, but stops short of giving fuller insight into the investigation. This extract conveys some of the breadth of what was uncovered:

    They then reviewed Mr. Hauser's coding and, according to the research assistant's statement, discovered that what he had written down bore little relation to what they had actually observed on the videotapes. He would, for instance, mark that a monkey had turned its head when the monkey didn't so much as flinch. It wasn't simply a case of differing interpretations, they believed: His data were just completely wrong.

    As word of the problem with the experiment spread, several other lab members revealed they had had similar run-ins with Mr. Hauser, the former research assistant says. This wasn't the first time something like this had happened. There was, several researchers in the lab believed, a pattern in which Mr. Hauser reported false data and then insisted that it be used.

    The article also extracts an e-mail from Hauser to his graduate students at the time of the incident. It's not shocking in its tone -- certainly no more than many of those leaked climate e-mails -- but it does show the kind of pressure he was imposing upon the graduate students working on his experiments.

    (via Greg Laden)

  • Marc Hauser misconduct findings

    Wed, 2010-08-11 00:41 -- John Hawks

    Maybe by now everybody has seen the story about Harvard psychologist Marc Hauser:

    Harvard University psychologist Marc Hauser — a well-known scientist and author of the book “Moral Minds’’ — is taking a year-long leave after a lengthy internal investigation found evidence of scientific misconduct in his laboratory.

    The findings have resulted in the retraction of an influential study that he led. “MH accepts responsibility for the error,’’ says the retraction of the study on whether monkeys learn rules, which was published in 2002 in the journal Cognition.

    The issue seems to revolve around interpreting subjective data on animal cognition. The article does not make clear whether Hauser or someone in his lab skewed data deliberately; no one has yet gone on record to specify the actual misconduct.

    The problem of subjective data is not unique to Hauser's work but is systemic in the field of primate cognition. It reminds me of some discussion in Jeremy Taylor's recent book Not a Chimp: The Hunt to Find the Genes that Make Us Human. There's the issue of whether experiments are designed clearly enough to yield conclusions. Then there's the second issue of whether observations are replicable, or whether they result only from somewhat "wishful" researchers. Such experiments often get heightened scrutiny, but rarely is there clear misconduct. That makes this a really shocking case.

    (via Gene Expression, and A Replicated Typo)

    UPDATE (2010-08-11): More from DrugMonkey. And a very nice post from Melody Dye who puts the issue in the context of other problems pervading psychology research.

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