A Wisconsin fall...

My partner and I went driving and walking in the Wisconsin countryside yesterday afternoon - here is an apple orchard, and the ice age trail.

The well-tempered web

I wanted to pass on this link to an engaging article by New Yorker music critic Alex Ross, on his experience with classical music culture on the web. The Internet may be killing the pop CD, but it's helping classical music. The article contains very useful links to many music sites.

Pogue’s Imponderables

Questions that N.Y. Times technical writer David Pogue doesn't have answers to. If you know the answers, fill him in at nytimes.com/pogue.

* Why is Wi-Fi free at cheap hotels, but $14 a night at expensive ones?

* What happens to software programs when their publishers go out of business?

* Would the record companies sell more music online if it weren't copy-protected?

* Do cellphones cause brain cancer?

* What's the real reason you have to turn off your laptop for takeoff?

* Why can't a digital S.L.R. camera record video?

* Wi-Fi on airplanes. What's taking so long?

* Who are the morons who respond to junk-mail offers, thereby keeping spammers in business?

* I'm told that they could make a shirt-pocket digital camera that takes pictures like an S.L.R., but it would cost a lot. So why don't they make one for people who can afford it?

* How come there are still no viruses for Mac OS X? If it has 6 percent of the market, shouldn't it have 6 percent of the viruses?

* Do shareware programmers pay taxes on all those $20 contributions?

* How are we going to preserve all of our digital photos and videos for future generations?

* Why are there no federal rebates or tax credits for solar power?

* Why do you have to take tape camcorders out of your carry-on at airport security, but not the tapeless kind? Couldn't you hide a bomb equally well in either one? (Actually, I have about 500 more logic questions about the rules at airport security, but I have a feeling they'll remain answerless for a very long time.)

* Laptops, cameras and cellphones have improved by a thousand percent in the last ten years. Why not their batteries?

* SmartDisplay, Spot Watch, U.M.P.C., Zune… when will Microsoft realize that it's not a hardware company?

* Why don't public sinks have foot pedals?

* Why don't all hotels have check-in kiosks like airlines do?

* Five billion dollars a year spent on ringtones? What the?

* How come cellphone signal-strength bars are so often wrong?

* Do P.R. people really expect anyone to believe that the standard, stilted, second-paragraph C.E.O. quote was really uttered by a human being?

* Why aren't there recycling bins for bottles and cans where they're most obviously needed, like food courts and cafeterias?

* Why doesn't someone start a cellphone company that bills you only for what you use? That model works O.K. for the electricity, gas and water companies —and people would beat a path to its door.

* Why doesn't everyone have lights that turn off automatically when the room is empty?

* What's the deal with Palm?

* Why are so many people rude on the Internet?

If you know the answers, by all means—fill us in at nytimes.com/pogue.

Genetic dissociation of multiple dopamine roles in learning

Here is the abstract of Frank et al., who show that three genetic variants of the dopamine systems that influence our reactions to positive and negative outcomes (and anticipations) have different effects on human reinforcement learning.

What are the genetic and neural components that support adaptive learning from positive and negative outcomes? Here, we show with genetic analyses that three independent dopaminergic mechanisms contribute to reward and avoidance learning in humans. A polymorphism in the DARPP-32 gene, associated with striatal dopamine function, predicted relatively better probabilistic reward learning. Conversely, the C957T polymorphism of the DRD2 gene, associated with striatal D2 receptor function, predicted the degree to which participants learned to avoid choices that had been probabilistically associated with negative outcomes. The Val/Met polymorphism of the COMT gene, associated with prefrontal cortical dopamine function, predicted participants' ability to rapidly adapt behavior on a trial-to-trial basis. These findings support a neurocomputational dissociation between striatal and prefrontal dopaminergic mechanisms in reinforcement learning. Computational maximum likelihood analyses reveal independent gene effects on three reinforcement learning parameters that can explain the observed dissociations.

A Memory Toolbox

A reader sends this link to 75 tips for going from amnesic to elephantic...

Parallel Distributed Processing and Semantic Cognition

Timothy T. Rogers and James L. McClelland have distilled the essence of the arguments in their book "Semantic Cognition: A Parallel Distributed Processing Approach" for an article (PDF here) to appear in Brain and Behavioral Sciences with peer commentary. Here is their abstract:

In our recent book, we present a parallel distributed processing theory of the acquisition, representation and use of human semantic knowledge. The theory proposes that semantic abilities arise from the flow of activation amongst simple, neuron-like processing units, as governed by the strengths of interconnecting weights; and that acquisition of new semantic information involves the gradual adjustment of weights in the system in response to experience. These simple ideas explain a wide range of empirical phenomena from studies of categorization, lexical acquisition, and disordered semantic cognition. In this précis we focus on phenomena central to the reaction against similarity-based theories that arose in the 1980's and that subsequently motivated the "theory-theory" approach to semantic knowledge. Specifically, we consider i) how concepts differentiate in early development, ii) why some groupings of items seem to form "good" or coherent categories while others do not, iii) why different properties seem central or important to different concepts, iv) why children and adults sometimes attest to beliefs that seem to contradict their direct experience, v) how concepts reorganize between the ages of 4 and 10, and vi) the relationship between causal knowledge and semantic knowledge. The explanations for these phenomena are illustrated with reference to a simple feed-forward connectionist model; and the relationship between this simple model, the broader theory, and more general issues in cognitive science are discussed.

In an Ultimatum Game, Chimps, but not humans, are rational maximizers

Another interesting bit of work from Tomasello's group (PDF here), in which they devised an ingenious apparatus for a mini-ultimatum game, a reduced form of the ultimatum game in which proposers are given a choice between making one of two pre-set offers which the responder can then accept or reject. The proposer had as one option an amount that would typically be rejected by a human responder as unfair, namely 80% for the proposer and 20% for the responder. The most important finding was that responders tended to accept any offer. These results support the hypothesis that other-regarding preferences and aversion to inequitable outcomes, which play key roles in human social organization, distinguish us from our closest living relatives. Here is their abstract, slightly edited:

Traditional models of economic decision-making assume that people are self-interested rational maximizers. Empirical research has demonstrated, however, that people will take into account the interests of others and are sensitive to norms of cooperation and fairness. In one of the most robust tests of this finding, the ultimatum game, individuals will reject a proposed division of a monetary windfall, at a cost to themselves, if they perceive it as unfair. Here we show that in an ultimatum game, humans' closest living relatives, chimpanzees (Pan troglodytes), are rational maximizers and are not sensitive to fairness.

Figure: Illustration of the testing environment. The proposer, who makes the first choice, sits to the responder's left. The apparatus, which has two sliding trays connected by a single rope, is outside of the cages. (A) By first sliding a Plexiglas panel (not shown) to access one rope end and by then pulling it, the proposer draws one of the baited trays halfway toward the two subjects. (B) The responder can then pull the attached rod, now within reach, to bring the proposed food tray to the cage mesh so that (C) both subjects can eat from their respective food dishes (clearly separated by a translucent divider).

Interactions between Declarative and Procedural Memories

Brown and Robertson do a simple experiment showing interaction between two main memory systems usually thought to be independent. Their abstract, slightly edited:

The acquisition of declarative (i.e., facts) and procedural (i.e., skills) memories may be supported by independent systems. This same organization may exist, after memory acquisition, when memories are processed off-line during consolidation. Alternatively, memory consolidation may be supported by interactive systems. This latter interactive organization predicts interference between declarative and procedural memories. Here, we show that procedural consolidation, expressed as an off-line motor skill improvement, can be blocked by declarative learning over wake, but not over a night of sleep. [note: the procedural task was learning a sequence of visually cued button presses at four possible postions.] The extent of the blockade on procedural consolidation was correlated to participants' declarative word recall. Similarly, in another experiment, the reciprocal relationship was found: declarative consolidation was blocked by procedural learning over wake, but not over a night of sleep. [note: The declarative task was learning a list of 16 words each individually presented on a computer screen for two seconds, with the list being presented in the same order five times.] The decrease in declarative recall was correlated to participants' procedural learning. These results challenge the concept of fixed independent memory systems; instead, they suggest a dynamic relationship, modulated by when consolidation takes place, allowing at times for a reciprocal interaction between memory systems.

Facts are no match for gossip...

In yesterday's Science NY Times, John Tierny describes work by Ralf D. Sommerfeld and colleagues on human reciprocity that has a surprising result (PDF here). Here are some clips:

Language, according to the anthropologist Robin Dunbar, evolved because gossip is a more efficient version of the “social grooming” essential for animals to live in groups...Gossip also told people whom to trust, and the prospect of a bad reputation discouraged them from acting selfishly, so large groups could peacefully cooperate. At least, that was the theory: gossip promoted the “indirect reciprocity” that made human society possible.

To test it, researchers at the Max Planck Institute for Evolutionary Biology and the University of Vienna gave 10 Euros apiece to 126 students and had them play a game that put them in a dilemma. On each turn, the players would be paired off, and one of them was offered a chance to give 1.25 Euros to the other. If he agreed, the researchers added a bonus of .75 Euro so that the recipient ended up gaining 2 Euros...If the first player refused to give the money, he’d save 1.25 Euros, but if others found out about his miserliness they might later withhold money from him. As the game progressed, with the players changing partners frequently and alternating between the donor and recipient roles, the players were given information about their partners’ past decisions...Sometimes the donor was shown a record of what the partner had done previously while playing the donor role. The more generous this partner had earlier been toward other players, the more likely the donor was to give him something...Sometimes the donor was shown gossip about the partner from another player. When the partner was paid a compliment like “spendabler spieler!” — generous player! — the donor was more likely to give money. But the donor turned stingy when he saw gossip like “übler geizkragen” — nasty miser.

So far, so good. As predicted, gossip promoted indirect reciprocity. The research, published in the Proceedings of the National Academy of Sciences [Note, I haven't found this article yet in a PNAS search], showed that most people passed on accurate gossip and used it for the common good. They rewarded cooperative behavior even when they themselves weren’t directly affected by the behavior...If a cooperation game like this was played without consequences for the players’ reputations — as has been done in other experiments — most players would be miserly, and cooperation would collapse. In this experiment they were generous most of the time, and on average ended up with twice as much money as they had at the beginning of the game.

But here’s the disconcerting news from the experiment. In a couple of rounds, each donor was given both hard facts and gossip. He was given a record of how his partner had behaved previously as well as some gossip — positive gossip in one round, negative in another...The donor was told that the source of the gossip didn’t have any extra information beyond what the donor could already see for himself. Yet the gossip, whether positive or negative, still had a big influence on the donors’ decisions, and it didn’t even matter if the source of the gossip had a good reputation himself. On average, cooperation increased by about 20 percent if the gossip was good, and fell by 20 percent if the gossip was negative.

Why is this?

It could be,” Sommerfeld suggested, “that we are just more adapted to listen to other information than to observe people, because most of the time we’re not able to observe how other people are behaving. Thus we might believe we have missed something."

Most popular consciousness papers for September 2007

From the ASSC Eprints Archive:

1. Rosenthal, David (2007) Consciousness and its function. In: 11th annual
meeting of the Association for the Scientific Study of Consciousness, 22-25
June 2007, Las Vegas, USA. 1014 downloads from 20 countries.
http://eprints.assc.caltech.edu/293/
2. Koriat, A. (2006) Metacognition and Consciousness. In: Cambridge handbook
of consciousness. Cambridge University Press, New York, USA. 870 downloads
from 18 countries. http://eprints.assc.caltech.edu/175/
3. Windt, Jennifer Michelle and Metzinger, Thomas (2006) The philosophy of
dreaming and self-consciousness: What happens to the experiential subject
during the dream state? In: The new science of dreaming. 834 downloads from
16 countries. http://eprints.assc.caltech.edu/200/
4. Sagiv, Noam and Ward, Jamie (2006) Crossmodal interactions: lessons from
synesthesia. In: Visual Perception, Part 2. Progress in Brain Research,
Volume 155. 814 downloads from 14 countries.
http://eprints.assc.caltech.edu/224/
5. Droege, Paula (2007) ASSC-11 Conference Report. In: 11th annual meeting
of the Association for the Scientific Study of Consciousness, June 22-25,
2007, Las Vegas, Nevada. 798 downloads from 18 countries.
http://eprints.assc.caltech.edu/323/

Motivation alters physical perception

Here is a clip from the Editor's choice section of the Oct. 5 issue of Science:

Students in elementary physics classes are introduced to the concept of frame of reference--the spatial coordinate system used by an observer to describe events--for instance, in the context of the perceived motion of trees by a passenger in a moving automobile. Adding in the dimension of time leads into non-intuitive territory, as in the example of a traveling astronaut who returns to Earth younger than her stay-at-home twin.

Building on previous work that demonstrated that internal physiological states can influence one's perception of physical quantities (such as thirsty people being more likely to characterize objects as transparent; that is, resembling water), Balcetis and Dunning show that internal psychological states are also capable of altering our perception of the external world. They induced states of high or low cognitive dissonance (a mismatch between thought and action) by asking or telling two groups of students to walk across campus wearing various fruit- and vegetable-themed adornments. In order to render a freely chosen yet somewhat embarrassing task less unpleasant to fulfill, the first set of students mentally shortened the distance they had to cover by estimating it to be fully 40% less than the average estimate made by the second group. Intriguingly, the route to ameliorating the state of dissonance appeared to be purely perceptual, as the free-choice students did not shorten their time of exposure by walking faster; in fact, they took about 10% longer.

The abstract of the original article;

Two studies demonstrated that the motivation to resolve cognitive dissonance affects the visual perception of physical environments. In Study 1, subjects crossed a campus quadrangle wearing a costume reminiscent of Carmen Miranda. In Study 2, subjects pushed themselves up a hill while kneeling on a skateboard. Subjects performed either task under a high-choice, low-choice, or control condition. Subjects in the high-choice conditions, presumably to resolve dissonance, perceived the environment to be less aversive than did subjects in the low-choice and control conditions, seeing a shorter distance to travel (Study 1) and a shallower slope to climb (Study 2). These studies suggest that the impact of motivational states extends from social judgment down into perceptual processes.

Baboon Metaphysics

Nicholas Wade comments (PDF here) on the work of Cheney and Seyfarth, whose most recent book has the title of this post. They have carried out an ingenious series of experiments in the wild to probe how the baboon's mind keeps track of transient relationships:

Royal is a cantankerous old male baboon whose troop of some 80 members lives in the Moremi Game Reserve in Botswana. A perplexing event is about to disturb his day....From the bushes to his right, he hears a staccato whoop, the distinctive call that female baboons always make after mating. He recognizes the voice as that of Jackalberry, the current consort of Cassius, a male who outranks Royal in the strict hierarchy of male baboons. No hope of sex today....But then, surprisingly, he hears Cassius’s signature greeting grunt to his left. His puzzlement is plain on the video made of his reaction. You can almost see the wheels turn slowly in his head:...“Jackalberry here, but Cassius over there. Hmm, Jackalberry must be hooking up with some one else. But that means Cassius has left her unguarded. Say what — this is my big chance!”...The video shows him loping off in the direction of Jackalberry’s whoop. But all that he will find is the loudspeaker from which researchers have played Jackalberry’s recorded call.

Although Baboons excel at the skills required for maintaining social networks regulated by matrilineal lines and dominance hierarchies, there is no evidence that they attribute beliefs or ideas to other animals, or that 'they know that they know.' They provide an example of what sort of social and cognitive complexity is possible in the absence of language and a theory of mind.

The prospective brain

I've been meaning to point you to a nice review article by Daniel Schacter and colleagues (PDF here). Here is the abstract and a summary figure.

A rapidly growing number of recent studies show that imagining the future depends on much of the same neural machinery that is needed for remembering the past. These findings have led to the concept of the prospective brain; an idea that a crucial function of the brain is to use stored information to imagine, simulate and predict possible future events. We suggest that processes such as memory can be productively re-conceptualized in light of this idea.

The core brain system that is consistently activated while remembering the past, envisioning the future and during related forms of mental simulation is illustrated schematically. Prominent components of this network include medial prefrontal regions, posterior regions in the medial and lateral parietal cortex (extending into the precuneus and the retrosplenial cortex), the lateral temporal cortex and the medial temporal lobe. Moreover, regions within this core brain system are functionally correlated with each other and, prominently, with the hippocampal formation. We suggest that this core brain system functions adaptively to integrate information about relationships and associations from past experiences, in order to construct mental simulations about possible future events.

New phases of our lives...

NY Times columnist David Brooks muses on how the phases of our life have increased in number (PDF here). Some clips:

There used to be four common life phases: childhood, adolescence, adulthood and old age. Now, there are at least six: childhood, adolescence, odyssey, adulthood, active retirement and old age. Of the new ones, the least understood is odyssey, the decade of wandering that frequently occurs between adolescence and adulthood...People who were born before 1964 tend to define adulthood by certain accomplishments — moving away from home, becoming financially independent, getting married and starting a family....In 1960, roughly 70 percent of 30-year-olds had achieved these things. By 2000, fewer than 40 percent of 30-year-olds had done the same.

...you can see the spirit of fluidity that now characterizes this stage....everything seems to give way to a less permanent version of itself...Dating gives way to Facebook and hooking up. Marriage gives way to cohabitation....Graduating seniors don’t find corporations offering them jobs that will guide them all the way to retirement. Instead they find a vast menu of information economy options...what we’re seeing is the creation of a new life phase, just as adolescence came into being a century ago...European nations are traveling this route ahead of us... Europeans delay marriage even longer than we do and spend even more years shifting between the job market and higher education...Someday people will look back and wonder at the vast social changes wrought by the emerging social group that saw their situations first captured by “Friends” and later by “Knocked Up.”

How to get health facts completely wrong....

John Tierney reviews Gary Taubes account (in "“Good Calories, Bad Calories”; Knopf, 2007) of how the health science establishment got it completely wrong, from the basic science on through official government pronouncements on dietary fat and hearth disease (PDF here). Some clips:

The notion that fatty foods shorten your life began as a hypothesis based on dubious assumptions and data; when scientists tried to confirm it they failed repeatedly.

Even so, in 1988, the surgeon general, C. Everett Koop, proclaimed ice cream to a be public-health menace right up there with cigarettes.This happened because of what social scientists call a cascade:

We like to think that people improve their judgment by putting their minds together, and sometimes they do. The studio audience at “Who Wants to Be a Millionaire” usually votes for the right answer. But suppose, instead of the audience members voting silently in unison, they voted out loud one after another. And suppose the first person gets it wrong...If the second person isn’t sure of the answer, he’s liable to go along with the first person’s guess. By then, even if the third person suspects another answer is right, she’s more liable to go along just because she assumes the first two together know more than she does. Thus begins an “informational cascade” as one person after another assumes that the rest can’t all be wrong...Because of this effect, groups are surprisingly prone to reach mistaken conclusions even when most of the people started out knowing better... If, say, 60 percent of a group’s members have been given information pointing them to the right answer (while the rest have information pointing to the wrong answer), there is still about a one-in-three chance that the group will cascade to a mistaken consensus.

Your Money and Your Brain

I thought I would pass on this brief commentary by Joe Nocera in the NY Times (PDF here), which emphasizes comments by Jason Zweig on how our emotional brains are not very well suited for making rational financial decisions.

A neural marker of consciousness

Here is the author's summary of an interesting article by Del Cul et al. in PlosBiology.

Understanding the neural mechanisms that distinguish between conscious and nonconscious processes is a crucial issue in cognitive neuroscience. In this study, we focused on the transition that causes a visual stimulus to cross the threshold to consciousness, i.e., visibility. We used a backward masking paradigm in which the visibility of a briefly presented stimulus (the “target”) is reduced by a second stimulus (the “mask”) presented shortly after this first stimulus. (Human participants report the visibility of the target.) When the delay between target and mask stimuli exceeds a threshold value, the masked stimulus becomes visible. Below this threshold, it remains nonvisible. During the task, we recorded electric brain activity from the scalp and reconstructed the cortical sources corresponding to this activity. Conscious perception of masked stimuli corresponded to activity in a broadly distributed fronto-parieto-temporal network, occurring from about 300 ms after stimulus presentation. We conclude that this late stage, which could be clearly separated from earlier neural events associated with subliminal processing and mask-target interactions, can be regarded as a marker of consciousness.


Figure: Top, depth of cortical processing: subliminal stimuli (left panel) should evoke a strong activation in extrastriate visual cortex, but their intensity should quickly decrease in higher visual areas; only conscious stimuli (right panel) should trigger a late surge of activation in a global prefronto-parietal network. Bottom, schematic time course of activation as a function of masking strength. Masking is expected to have little effect on early visual activation but to modulate the strength of activation in higher visual areas. Furthermore, there should be a nonlinear effect of masking strength in prefrontal cortex, with a similar late top-down activation peak occurring simultaneously in visual areas

Where the brain decides how much we are willing to pay.

Plassmann et al. show some brain correlates of our willingness to pay:

An essential component of every economic transaction is a willingness-to-pay (WTP) computation in which buyers calculate the maximum amount of financial resources that they are willing to give up in exchange for the object being sold. Despite its pervasiveness, little is known about how the brain makes this computation. We investigated the neural basis of the WTP computation by scanning hungry subjects' brains using functional magnetic resonance imaging while they placed real bids for the right to eat different foods. We found that activity in the medial orbitofrontal cortex and in the dorsolateral prefrontal cortex encodes subjects' WTP for the items. Our results support the hypothesis that the medial orbitofrontal cortex encodes the value of goals in decision making.
Neural correlates of WTP. A, B, Activity in the medial OFC and the DLPFC was positively correlated with WTP at the time of evaluation in the free trials more than in the forced trials.

What the F***?

An article by Steven Pinker on cursing.

Google's evil eye....

...thought I would link you to this interesting article.

Radiohead - the modern troubadours?

An article in the Arts section of today's NY Times temporarily stirred me out of my curmudgeonly old fart persona. Just as a federal jury in Minnesota last week decided that a mother found liable for copyright infringement for sharing music online should pay damages amounting to about $9,250 apiece for 24 songs, the British Rock group Radiohead has made their latest album "In Rainbows" available for download, letting their fans decide how much they want to pay for it. This has brought a new climax in the pricing pandemonium in the on-line music industry summed up by Radiohead manager Bryce Edge:

Digital technology has reintroduced the age of the troubadour. You are worth what people are prepared to give you in the digital age because they can get it for nothing.

In another departure from convention:

...the band declined to send out early copies of the music for reviewers and has not settled on a traditional single to push to radio stations. As a result, programmers are improvising. In San Francisco, for instance, the rock station KITS-FM, Live 105, has the entire album on its Web site (live105.com) and will let fans vote to determine which songs merit airplay.

I just checked out this site, and proceeded to buy and download the new album.

See-through frog...

Just the thing for a budding young scientist's holiday stocking...From the Oct. 3 issue of Nature Magazine:

Japanese biologists have created what they call the world's first see-through creature with four legs. (Some fish are naturally transparent.) The frogs started out as ordinary Japanese brown frogs (Rana japonica ), but crossing animals with recessive genes for light-coloured skin led to transparency. Internal organs, eggs and other normally concealed innards are all on full display in the new amphibian (pictured). Its creator, Masayuki Sumida of Hiroshima University, plans to seek a patent, according to the AFP news agency.

How we see over 10,000-fold changes in light intensity

The first 35 years of my professional life were spent studying the excitation and adaptation of photoreceptor cells. This motivates me to point out a beautiful piece of work by Dunn et al. showing how different circuits in the retina collaborate to let us see over an amazingly wide range of environmental light intensities. Here is their abstract, and figures from the paper showing the cells involved:

We see over an enormous range of mean light levels, greater than the range of output signals retinal neurons can produce. Even highlights and shadows within a single visual scene can differ approximately 10,000-fold in intensity—exceeding the range of distinct neural signals by a factor of approximately 100. The effectiveness of daylight vision under these conditions relies on at least two retinal mechanisms that adjust sensitivity in the approximately 200 ms intervals between saccades. One mechanism is in the cone photoreceptors (receptor adaptation)and the other is at a previously unknown location within the retinal circuitry that benefits from convergence of signals from multiple cones (post-receptor adaptation). Here we find that post-receptor adaptation occurs as signals are relayed from cone bipolar cells to ganglion cells. Furthermore, we find that the two adaptive mechanisms are essentially mutually exclusive: as light levels increase the main site of adaptation switches from the circuitry to the cones. These findings help explain how human cone vision encodes everyday scenes, and, more generally, how sensory systems handle the challenges posed by a diverse physical environment.

Figure 1: Midget and parasol ganglion cells adapt at lower backgrounds than L cones. Schematic of primate midget and parasol pathways with fluorescent images of cones in slice and ganglion cells in flat mount.

Figure 2: Post-receptor adaptation occurs in signal transfer from cone bipolar cells to ganglion cells. The figure shows fluorescent images of a midget cone bipolar cell (left panel) and a diffuse cone bipolar cell (right panel) in slice. OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer.

The wireless epidemic

Jon Kleinberg, best known for his work on web searching that paved the way for Google and the rest, writes on the threat posed by computer viruses and worms in our increasingly 'wireless' age, concluding that biological models of virus transmission are increasingly relevant for assessing the emerging threat. Here are a few clips:

Traditionally, computer viruses have propagated on networks that bear little resemblance to the networks of physical contact through which their biological counterparts spread. But a growing body of research shows that the increasing use of short-range wireless communication networks might cause the two models to converge....Diseases in plant populations, or animal diseases such as rabies, are heavily constrained by geographical proximity and the relatively fixed physical locations of the infected individuals. Models of these diseases have been extended using detailed data on patterns of travel within cities and by air worldwide in attempts to analyse disease outbreaks in human populations...Epidemics on the Internet are even more diverse. At the most general level, there is a distinction between computer viruses, which 'piggyback' on data exchanged between users, and computer worms, which more actively direct their own transmission through a network...

Very roughly.. one could view models of biological epidemics as rooted in spatial networks, and expanding into less spatial realms to model the technologies that have accelerated human travel. Meanwhile, research on cyber-epidemics has occupied the non-spatial end of the spectrum, with its diverse and far-flung connections, when modelling global communication technologies such as the Internet.

..the spread of short-range wireless communication technologies such as Bluetooth, and the emergence of worms that exploit these systems is disrupting this dichotomy by making possible computer-virus outbreaks whose progress closely tracks human mobility patterns. These types of wireless worm are designed to infect mobile devices such as cell phones, and then to continuously scan for other devices within a few tens of metres or less, looking for new targets. A computer virus thus becomes something you catch not necessarily from a compromised computer halfway around the world, but possibly from the person sitting next to you on a bus, or at a nearby table in a restaurant.

In assessing the risks of such attacks, and developing countermeasures against them, it is intriguing to contemplate how we might draw on expertise from the field of human epidemiology in understanding how contagion spreads...Analogies to biological epidemics can also be exploited for beneficial purposes, in the design of computer-network protocols. For mobile devices, epidemiology helps in dealing with the problem of intermittent connectivity: that the routing of traffic must conform to a dynamic and unpredictable network structure as the owners of mobile devices move around. The result is a growing interest in opportunistic routing, in which messages are passed between devices that come into physical proximity, with the goal of eventually reaching a specified recipient. The development of such protocols has drawn on detailed data concerning human mobility and contact patterns.

An acetylcholine receptor agonist improves cognition

The alpha-7 nicotinic acetylcholine receptor (nAChR) plays an important role in cognitive processes and may represent a drug target for treating cognitive deficits in neurodegenerative and psychiatric disorders. Bitner et al. study the effects of a particular AChR enhancer, or agonist, whose simple name is A-582941.

The figure shows the general structure of this class of molecules. A-582941 enhanced cognitive performance in behavioral assays including the monkey delayed matching-to-sample, rat social recognition, and mouse inhibitory avoidance models that capture domains of working memory, short-term recognition memory, and long-term memory consolidation, respectively. Their results demonstrate that alpha-7 nAChR agonism can lead to broad-spectrum efficacy in animal models at doses that enhance ERK1/2 (extracellular-signal regulated kinase) and CREB (cAMP response element-binding protein) phosphorylation/activation and may represent a mechanism that offers potential to improve cognitive deficits associated with neurodegenerative and psychiatric diseases, such as Alzheimer's disease and schizophrenia.

Most Viewed MindBlog posts...

I occasionally check Feedburner.com to observe web traffic to this blog, and pulled up the following list of most viewed posts. The left column indicates the number of views and the right indicates clicks on links in the post. Entering a few words of the title in the "Search MindBlog" box gets you to a given post...

Non-materialist neuroscience

Here is an discussion on what the authors call the latest installment of the war on science. From their introduction:

Non-materialist neuroscience is the latest front in the war on science. The battle has been a long time coming and it is surprising it has taken so long to get going. Modern neuroscience is rapidly reducing much of human thought, emotion and behavior into component pieces of neuronal interactions. The combination of computational modeling and non-invasive imaging of living brains has allowed researchers to begin describing how complex thought emerges from the firing patterns of neurons. In a way neuroscience is the death knell of dualism. When materialist causes become both necessary and sufficient to explain all of human thought then parsimony dictates that references to a soul or other supernatural entities can be tossed out.

Non-materialist neuroscience is a reaction to these discoveries, a rallying cry for dualism. Like creationism and intelligent design this "new" neuroscience is a reactionary movement against science. Rather than a hypothesis that leads to predictions and experiments, it is simply a catalog of things modern neuroscience supposedly cannot yet explain.

Unsurprisingly, the movement is spear-headed by intelligent design lackeys from the Discovery Institute and related affiliates. The primary proponents of the movement are Michael Egnor, a neurosurgeon and recent contributor to the Discovery Institute blog, Denyse O'Leary a Canadian "journalist" who runs her own blog dedicated to non-materialist neuroscience and likes to copy and paste these entries over on William Dembski's blog as well, and Mario Beauregard the author with O'Leary of a recent book on the subject of non-materialist neuroscience The Spiritual Brain: A Neuroscientist's Case for the Existence of the Soul.

Musicians have enhanced subcortical processing

Musical training is known to modify cortical organization. Musacchia et al. show that:

...such modifications extend to subcortical sensory structures and generalize to processing of speech. Musicians had earlier and larger brainstem responses than nonmusician controls to both speech and music stimuli presented in auditory and audiovisual conditions, evident as early as 10 ms after acoustic onset. Phase-locking to stimulus periodicity, which likely underlies perception of pitch, was enhanced in musicians and strongly correlated with length of musical practice. In addition, viewing videos of speech (lip-reading) and music (instrument being played) enhanced temporal and frequency encoding in the auditory brainstem, particularly in musicians. These findings demonstrate practice-related changes in the early sensory encoding of auditory and audiovisual information.

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Try out this.

Some rambling on "Selves" and "Purpose"

The recent posts on Alwyn Scott and the Blakesless' book prompt me to this random walk....

Self conscious "Purpose" of the sort we humans experience, in the service of crafting new political movements or environments, is an evolved psychology that (sometimes) helps pass on our genes, and requires our distinctively human self reflective "I". Our behavior and that of other animals also reflects a kind of purpose that has been formed by our evolutionary and developmental history. In other animals such behaviors are acted out on the cusp of an eternal present - there is no evidence that they "know that they know" in the way that we can.

Both modern neuroscience (cf. the quote from the Blakesless' book) and Buddhist psychology inform us that the self and the purpose that each of us experiences is an illusion or confabulation of our brains - hopefully a useful one - whose utility is tested by how it enhances our energy and individual survival. This 'illusion' is a powerful instrument of downward causation, regulating our psychological, immune, neuro-endocrine robustness.

What is especially amazing is that our human body/brain can sometimes use meditative or other techniques to bootstrap to a level of metacognition that rests antecedent to - and can be the detached observer of - the generation of this illusion of a self and its purposes.

The maximum power of our self illusion, for most of us, goes with our heartfelt immersion and belief in it (i.e., our delusion). From such a immersion, it can be more difficult to discern or appreciate the different selves and purposes of other humans, and their cultures and historical eras.

Rich and Poor

San Paulo, Brazil.

Playing Action Video Games Reduces Gender Differences in Spatial Cognition

From Feng, Spence, and Pratt (PDF here):

We demonstrate a previously unknown gender difference in the distribution of spatial attention, a basic capacity that supports higher-level spatial cognition. More remarkably, we found that playing an action video game can virtually eliminate this gender difference in spatial attention and simultaneously decrease the gender disparity in mental rotation ability, a higher-level process in spatial cognition. After only 10 hr of training with an action video game, subjects realized substantial gains in both spatial attention and mental rotation, with women benefiting more than men. Control subjects who played a non-action game showed no improvement. Given that superior spatial skills are important in the mathematical and engineering sciences, these findings have practical implications for attracting men and women to these fields.

From their article:

The experimental group was trained using Medal of Honor: Pacific Assault, which was chosen because it is similar to the games typically played by players in Experiment 1 [note: which compared students based on their self reports of game use] and because it has been used before in attention training studies. This game is a 3-D first-person shooter game that requires intense visual monitoring and attentional resources. The control group played Ballance, a 3-D puzzle game that involves steering a ball through a hovering maze of paths and rails with obstacles such as seesaws, suspension bridges, and pendulums.

Plasticity and learning in the human mirror neuron system

I pass on a review by Welberg of an interesting study by Catmur et al. [Catmur, C., Walsh, V. & Heyes, C. Sensorimotor learning configures the human mirror system. Curr. Biol. 17, 1527–1531 (2007)]:

Neurons in the frontoparietal mirror system fire when one performs an action and when one observes someone else performing that same action. This system is thought to have a role in social cognition and, perhaps, in language acquisition. How the mirror neurons map sensory input onto its motor representation is unknown, but Catmur et al. demonstrate that these representations are not innate and can be altered by training.

The authors used transcranial magnetic stimulation (TMS) to stimulate the motor cortex of volunteers who were watching a video of a hand. When the volunteers watched the hand's index finger move, the TMS-induced motor-evoked potential (MEP) was greater in the abductor muscle of their own index finger than when they watched the little finger move; conversely, the MEP of their little finger's abductor muscle was greatest when they watched the little finger move. In other words, a muscle showed MEP enhancement when its owner watched a movement that is normally performed by that muscle; this 'mirror effect' is thought to reflect activity of the mirror neuron system.

Half of the volunteers then underwent incongruent training trials, in which they were asked to extend their little finger if the video showed a hand extending the index finger, and vice versa. People in congruent trials simply had to repeat the movement they saw in the video. The incongruent trials were assumed to train the mirror system to associate an observed finger movement with movement of a different finger of the volunteer's own hand.

Measuring TMS-induced MEPs after training, the authors found that volunteers who had undergone the incongruent training now showed greater MEPs in the muscle of one finger when watching the 'wrong' finger move in the video, indicating that a reversal of muscle-specific MEP enhancement during action observation had taken place.

This study shows that the 'mirror properties' of the mirror system are not innate. Rather, they can be trained, through sensorimotor experience, to transform observation into action. These findings imply that insufficient social interaction and consequent inadequate sensory experience might affect the development of the mirror neuron system, for example, in children with autism.

New research on ageing

Nature Magazine offers a special open access supplement with several excellent articles on recent research on ageing. Also, they offer to send a free print copy.

Striking Images....

Here are the first place winners of Science Magazine's 2007 Visualization Challenge, in which editors evaluate submissions that try to bring scientific data to life through images, illustrations, computer graphics, and animations. In the first, 182 thin CT "slices" are stacked together to create a 3D image looking upward at the sinuses from underneath the head. In the second, Irish ocean moss is spread out for photography.

How Meaning Shapes Seeing

This is the title of an interesting article by Koivisto and Revonsuo in Psychological Science. They show that semantic meaning influences inattentional blindness. Here is their abstract:

Inattentional blindness refers to the failure to see an unexpected object that one may be looking at directly when one's attention is elsewhere. We studied whether a stimulus whose meaning is relevant to the attentional goals of the observer will capture attention and escape inattentional blindness. The results showed that an unexpected stimulus belonging to the attended semantic category but not sharing physical features with the attended stimuli was detected more often than a semantically unrelated stimulus. This effect was larger when the unexpected stimuli were words than when they were pictures. The results imply that the semantic relation between the observer's attentional set and the unexpected stimulus plays a crucial role in inattentional blindness: An unexpected stimulus semantically related to the observer's current interests is likely to be seen, whereas unrelated unexpected stimuli are unseen. Attentional selection may thus be driven by purely semantic features: Meaning may determine whether or not one sees a stimulus.

Different cognitive processes underlying human mate choices and mate preferences

Starting with the assumption that the underlying function of mate choice is reproductive success, evolutionary psychologists have proposed that men should seek young, fertile, faithful women, and women should seek high-status, resourceful, committed men. This evolutionary reasoning predicts what traits people will actually tend to choose, but not necessarily what people say they will (or would like to) choose. Todd et al. suggest that different cognitive processes underlie mate preferences and actual human mate choices. Here is their abstract:

Based on undergraduates' self-reports of mate preferences for various traits and self-perceptions of their own levels on those traits, Buston and Emlen [Buston PM, Emlen ST (2003) Proc Natl Acad Sci USA 100:8805–8810] concluded that modern human mate choices do not reflect predictions of tradeoffs from evolutionary theory but instead follow a "likes-attract" pattern, where people choose mates who match their self-perceptions. However, reported preferences need not correspond to actual mate choices, which are more relevant from an evolutionary perspective. In a study of 46 adults participating in a speed-dating event, we were largely able to replicate Buston and Emlen's self-report results in a pre-event questionnaire, but we found that the stated preferences did not predict actual choices made during the speed-dates. Instead, men chose women based on their physical attractiveness, whereas women, who were generally much more discriminating than men, chose men whose overall desirability as a mate matched the women's self-perceived physical attractiveness. Unlike the cognitive processes that Buston and Emlen inferred from self-reports, this pattern of results from actual mate choices is very much in line with the evolutionary predictions of parental investment theory.

Cortical evolution and skilled hand use.

Unlike other New World species, such as squirrel monkeys, that exclusively use a power grip, cebus monkeys frequently use a precision grip in which the thumb and forefinger are brought into contact with one another to manipulate small objects, or engage in goal-directed tool use. Such a precision grip is observed in many old world monkey species, such as the macaques. Padberg et al. find:

..Unlike other New World Monkeys, but much like the macaque monkey, cebus monkeys possess a proprioceptive cortical area 2 and a well developed area 5, which is associated with motor planning and the generation of internal body coordinates necessary for visually guided reaching, grasping, and manipulation.

This is an example of parallel evolution:

...The similarity of these fields in cebus monkeys and distantly related macaque monkeys with similar manual abilities indicates that the range of cortical organizations that can emerge in primates is constrained, and those that emerge are the result of highly conserved developmental mechanisms that shape the boundaries and topographic organizations of cortical areas.

Left, Primate cladogram showing which primate taxa have the following characteristics related to manual control: complex manipulation (e.g., grasping food with one hand and peeling it with the other), use of feeding tools, corticospinal (CS) terminals in ventral horn (VH), opposable (or laterally opposable) thumb, and presence of parietal area 2. Filled box, Characteristic is present. Unfilled box: characteristic has been sufficiently tested and is absent. Right, Parietal areas and representative grasp postures traced from photographs in five primate species.
[Note: pink and green indicate areas 2 and 5 mentioned above.)

Stairways to the Mind

Alwyn Scott passed away recently. "Stairways to the Mind" was one of his books, on levels of organization and emergent properties. I knew him when he was at Wisconsin, and later read a copy of this book in draft form, to offer comments. In looking back over his work, I came across a review of the book written by Willis Harman, one of the founders of the Noetic Sciences Institute, which included a mild criticism that I don't completely agree with, but thought interesting:

Having gone so far in urging the usefulness of a hierarchical structuring of science, and having recognized (with Roger Sperry) that the consciousness level can be causal with regard to the biological or physical level (as well as the reverse), it seems a pity not to have gone one step further to recognize that the new disciplines of transpersonal psychology and anthropology, and the deepest insights of artists and mystics, can fit quite comfortably within the top level of the hierarchy. The metaphysical insight that the material world evolves within consciousness can live side by side with the complementary metaphor of consciousness as emergent from the physical.

Self-Referential Cognition in Autism

Individuals with autism spectrum conditions (ASC) have profound impairments in the interpersonal social domain, but it is unclear if individuals with ASC also have impairments in the intrapersonal self-referential domain. Lombardo et. al. give an interesting introductory discussion of the "absent self" model of Frith. They then evaluate performance of 30 subjects and:

"conclude that individuals with ASC have broad impairments in both self-referential cognition and empathy. These two domains are also intrinsically linked and support predictions made by simulation theory. Our results also highlight a specific dysfunction in ASC within cortical midlines structures of the brain such as the medial prefrontal cortex."

Figure:. Image showing the overlap in peaks of activation from studies of self-referential cognition, other-referential cognition, and theory of mind within the medial prefrontal cortex and posterior cingulate/precuneus.

Boundaries are 16mm from within midline. All peaks are taken from exemplary studies in the literature. Brain is depicted on a representative sagittal slice of the Montreal Neurological Institute (MNI) template

Brain correlates of different spatial learning strategies

Each of us tends to emphasize one of two main strategies for spacial navigation. Learning the relationships between environmental landmarks using a "spatial memory strategy" to construct a cognitive map depends on the hippocampus. Navigating using a "response strategy", or series of turns at precise decision points (turn left at corner, then turn right at...), involves the caudate nucleus and proceeds without using landmark relationships. Bohbot et al. have used a virtual maze task to examine 50 young healthy subjects, half reporting the use each strategy. Those using the spatial strategy

...had significantly more gray matter in the hippocampus and less gray matter in the caudate nucleus compared with response learners. Furthermore, the gray matter in the hippocampus was negatively correlated to the gray matter in the caudate nucleus, suggesting a competitive interaction between these two brain areas.

In a second analysis:

.. the gray matter of regions known to be anatomically connected to the hippocampus, such as the amygdala, parahippocampal, perirhinal, entorhinal and orbitofrontal cortices were shown to covary with gray matter in the hippocampus. Because low gray matter in the hippocampus is a risk factor for Alzheimer's disease, these results have important implications for intervention programs that aim at functional recovery in these brain areas. In addition, these data suggest that spatial strategies may provide protective effects against degeneration of the hippocampus that occurs with normal aging.

Ape language slips reveal category knowledge storage.

Michael Erard summarizes efforts (PDF here) to analyze 'language' errors of apes for insight into the covert mental processes of animals - analogous to such work done on human language errors He focuses on the work of Lyn, who was the first to apply the study of errors to bonobos . Kanzi and a female bonobo, Panbanisha, who now live at the Great Ape Trust in Des Moines, Iowa, can comprehend instructions and descriptions in spoken English, and they can respond by using 384 lexigrams, which they touch on a keyboard.

Lyn found that Kanzi and Panbanisha have arranged hundreds of lexigrams in their minds in a complex, hierarchical manner based mainly on their meaning. She coded the relations between all 1497 sample-error pairs along seven dimensions, including whether the lexigrams looked alike, had English words that sounded alike, or referred to objects in the same category. She found that the errors were not random but patterned. If the lexigram stood for "blackberry," the error was more likely than chance to sound like blackberry, be edible, be a fruit, or be physically similar. Errors were also more likely to be associated with more than one category. For example, "cherries" are both edibles and fruits, and the word sounds like the correct one, "blackberries." All this indicated to Lyn that mental representations of the lexigrams must be stored not as simple one-to-one associations but in more complex arrangements. This suggests that, given the chance, bonobos and other apes can acquire systems of meaning that are closer than anyone has thought to what humans do, and that some aspects of language acquisition are not unique to humans.

Symbiosis of human brains and the web...

George Johnson notes that the web has stripped the word algorithm (a recipe for solving problems step by step) of its innocence. The algorithms used by Google search, Amazon, MySpace, etc. perform an intelligence amplification, leveraging human thinking with machines in the service of selling more goods. The boundary between human and computer responses increasingly blurs. Submit or change a Wikipedia article and "a swarm of warm- and sometimes hot-blooded proofreading routines go to work making corrections and corrections to the corrections." Here is the PDF of Johnson's article.

Moral Universals

Nicholas Wade offers a summary (PDF here) of some of the evidence that humans have an evolved moral intuition that appeared before the development of language. (This has been the subject of several previous blog posts), focusing on the views of Jonathan Haidt. Haidt suggests that there are five innate moral systems, or rather, innate psychological mechanisms that predispose children to absorb certain virtues. Some concern the protection of individuals, others the ties that bind a group together. Of the moral systems that protect individuals, one is concerned with preventing harm to the person and the other with reciprocity and fairness. Less familiar are the three systems that promote behaviors developed for strengthening the group. These are loyalty to the in-group, respect for authority and hierarchy, and a sense of purity or sanctity.

A striking demonstration comes from experiments that show that people will say it is morally acceptable to pull a switch that diverts a train, killing just one person instead of the five on the other track. But if asked to save the same five lives by throwing a person in the train’s path, people will say the action is wrong. This may be evidence for an ancient subconscious morality that deters causing direct physical harm to someone else. An equally strong moral sanction has not yet evolved for harming someone indirectly.

Emotion and Disorders of Emotion

You might want to check out this open access special focus issue of Nature Magazine on emotion and disorders of emotion. The starting editorial introduces the articles. Individual susceptibility to depression and anxiety in response to life stressors may be related to genetic variation, and I would point to the review article by Klaus-Peter Lesch and Turhan Canli. It explores how individual variation in the serotonin transporter gene may interact with personality, emotion regulation and social cognition.

Prospection: simulation of future unique to humans

Gilbert and Wilson offer a concise review of our unique human ability to simulate the future, covering brain regions involved and stereotyped errors that occur (PDF here). (I did a series of posts in June, 2006 abstracting Gilberts book "Stumbling on Happiness." You can use the blog search box to find them by entering the word "stumbling.") Here are some clips:

Prefeelings will be reliable predictors of subsequent hedonic experiences when two conditions are met. As the figure shows, when we are in the present (T₁) attempting to predict our hedonic reaction to an event in the future (H₂), our present hedonic experience (H₁) is influenced by our simulation of the future event (e₁) as well as by contextual factors (₁), such as the events that are occurring in the present, the thoughts we are having in the present, our present bodily states, and so on. We feel better when we imagine going to the theater than to the dentist, but we feel better imagining either event on a sunny day than on a rainy day, or when we are well rather than ill. Similarly, our future hedonic experience (H₂) will be influenced both by our perception of the event (e₂) and by contextual factors (₂). Because our hedonic experiences are influenced both by our mental representation of the event and by contextual factors, our present hedonic experience will be a reliable predictor of our future hedonic experience if and only if (i) our simulation of the event at T₁ exerts the same influence on our hedonic experience at T₁ as our perception of the event at T₂ exerts on our hedonic experience at T₂, and (ii) contextual factors at T₁ exert the same influence on our hedonic experience at T₁ as contextual factors at T₂ exert on our hedonic experience at T₂. In other words, H₁ = H₂ if and only if e₁ = e₂ and ₁ = ₂. Errors in prospection arise from the fact that people use their prefeelings to make hedonic predictions even when one or both of these conditions is not met. These errors are of four kinds.

Simulations are unrepresentative. We naturally imagine our next dental appointment by remembering our last one.... research suggests that people often use unrepresentative memories as a basis for simulation. For example, when people who have missed trains in the past are asked to imagine missing a train in the future, they tend to remember their worst train-missing experience rather than their typical train-missing experience.

Simulations are essentialized. When we imagine "going to the theater next week," we don't imagine every detail of the event, but rather, we imagine the essential features that define it. We imagine seeing a stage filled with actors but we do not imagine parking the car, checking our coat, or finding our seat. The problem with omitting inessential features from simulations is that such features can profoundly influence our subsequent hedonic experience... Because simulations omit inessential features, people tend to predict that good events will be better and bad events will be worse than they actually turn out to be. The young couple who simulate the joys of parenthood but fail to simulate the drudgery of diapers are unlikely to have the hedonic experience they imagined.

Simulations are abbreviated. If we imagined each and every moment of the events we were simulating, our simulations would take as long as the events themselves. Simulations are naturally abbreviated and represent just a few, select moments of a future event. The moments they select tend to be the early ones. When people imagine what their lives would be like if they won the lottery or became paraplegic, they are more likely to imagine the first day than the two-hundred-and-ninety-seventh. The problem with imagining only the early moments of an event is that hedonic reactions to events typically dissipate over time, which means that mental simulations tend to the moments that evoke the most intense pleasure or pain.

Simulations are decontextualized. Research shows that people often do not consider the potentially significant differences between contextual factors at T1 and T2 when using their present hedonic state to predict their future hedonic state. For example, hungry people mistakenly expect to like eating spaghetti for breakfast the next day, and sated people mistakenly expect to dislike eating it for dinner the next day. People who have just exercised mistakenly expect to enjoy drinking water the next day more than do people who are about to exercise (53). In both cases, people do not seem to realize that their present hunger and thirst are influencing their hedonic reactions to simulated future consumption. They ignore the fact that the contextual factors that are presently exerting an influence at T1 (i.e., hunger and thirst) will not exert the same influence at T2.

Their conclusion makes a nice summary of how modern and ancient brain systems interact in imagining possible future feelings:

Mental simulation is the means by which the brain discovers what it already knows. When faced with decisions about future events, the cortex generates simulations, briefly tricking subcortical systems into believing that those events are unfolding in the present and then taking note of the feelings these systems produce. The cortex is interested in feelings because they encode the wisdom that our species has acquired over millennia about the adaptive significance of the events we are perceiving. Alas, actually perceiving a bear is a potentially expensive way to learn about its adaptive significance, and thus evolution has provided us with a method for getting this information in advance of the encounter. When we preview the future and prefeel its consequences, we are soliciting advice from our ancestors.

This method is ingenious but imperfect. The cortex attempts to trick the rest of the brain by impersonating a sensory system. It simulates future events to find out what subcortical structures know, but try as it might, the cortex cannot generate simulations that have all the richness and reality of genuine perceptions. Its simulations are deficient because they are based on a small number of memories, they omit large numbers of features, they do not sustain themselves over time, and they lack context. Compared to sensory perceptions, mental simulations are mere cardboard cut-outs of reality. They are convincing enough to elicit brief hedonic reactions from subcortical systems, but because they differ from perceptions in such fundamental ways, the reactions they elicit may differ as well. Although prospection allows us to navigate time in a way that no other animal can, we still see more than we foresaw.

Evolving size of the social brain.

Dunbar and Shultz ask why primates have such large brains, compared to their body mass, compared with other animals. Here is their abstract, followed by a central clip from their article:

The evolution of unusually large brains in some groups of animals, notably primates, has long been a puzzle. Although early explanations tended to emphasize the brain's role in sensory or technical competence (foraging skills, innovations, and way-finding), the balance of evidence now clearly favors the suggestion that it was the computational demands of living in large, complex societies that selected for large brains. However, recent analyses suggest that it may have been the particular demands of the more intense forms of pairbonding that was the critical factor that triggered this evolutionary development. This may explain why primate sociality seems to be so different from that found in most other birds and mammals: Primate sociality is based on bonded relationships of a kind that are found only in pairbonds in other taxa.

Figure - In anthropoid primates, mean social group size increases with relative neocortex volume (indexed as the ratio of neocortex volume to the volume of the rest of the brain). Solid circles, monkeys; open circles, apes. Regression lines are reduced major axis fits.


The important issue in the present context is the marked contrast between anthropoid primates and all other mammalian and avian taxa (including, incidentally, prosimian primates): Only anthropoid primates exhibit a correlation between social group size and relative brain (or neocortex) size. This quantitative relationship is extremely robust; no matter how we analyze the data (with or without phylogenetic correction, using raw volumes, or residuals or ratios against any number of alternative body or brain baselines) or which brain data set we use (histological or magnetic resonance imaging derived, for whole brain, neocortex, or just the frontal lobes), the same quantitative relationship always emerges. This suggests that, at some early point in their evolutionary history, anthropoid primates used the kinds of cognitive skills used for pairbonded relationships by vertebrates to create relationships between individuals who are not reproductive partners. In other words, in primates, individuals of the same sex as well as members of the opposite sex could form just as intense and focused a relationship as do reproductive mates in nonprimates. Given that the number of possible relationships is limited only by the number of animals in the group, primates naturally exhibit a positive correlation between group size and brain size. This would explain why, as primatologists have argued for decades, the nature of primate sociality seems to be qualitatively different from that found in most other mammals and birds. The reason is that the everyday relationships of anthropoid primates involve a form of "bondedness" that is only found elsewhere in reproductive pairbonds.

MindBlog's home this morning...

The 1860 stone schoolhouse with its satellite dishes.

Nonhuman primates perceive human goals

Hauser and collaborators do a clever experiment to demonstrate that several primates can make inferences about a human experimenters goal that cannot be explained by simple associative learning. This means that our capacity to infer rational, goal-directed action derives from capabilities present in monkeys ~40 million years ago. Here is their abstract and a figure showing the basic idea of the experiment.

Humans are capable of making inferences about other individuals' intentions and goals by evaluating their actions in relation to the constraints imposed by the environment. This capacity enables humans to go beyond the surface appearance of behavior to draw inferences about an individual's mental states. Presently unclear is whether this capacity is uniquely human or is shared with other animals. We show that cotton-top tamarins, rhesus macaques, and chimpanzees all make spontaneous inferences about a human experimenter's goal by attending to the environmental constraints that guide rational action. These findings rule out simple associative accounts of action perception and show that our capacity to infer rational, goal-directed action likely arose at least as far back as the New World monkeys, some 40 million years ago.


Figure: During each trial, an experimenter presented subjects with two potential food containers, performed an action on one, and then allowed the subject to select one of the containers. In the intentional condition, the experimenter reached directly for and grasped the container. In the accidental condition, the experimenter flopped his hand onto the container with palm facing upwards in a manner that appeared, from a human perspective, accidental and non–goal-directed (13). If non-human primates fail to distinguish between intentional and accidental actions when making inferences about others' goals, attending to the mere association of the hand and container, then they should show the same pattern of searching in both conditions—that is, approach the experimenter-contacted container. However, if they distinguish between intentional and accidental actions, then they should selectively inspect the container targeted by the experimenter'sintentional action but not that targeted by accidental action.

A "language gene" in echolocating bats

Slightly altered abstract from Li et al.:

FOXP2 is a transcription factor implicated in the development and neural control of orofacial coordination, particularly with respect to vocalisation. [Thus, it is not really a "language gene" as indicated in many popular press reports.] Observations that orthologues show almost no variation across vertebrates yet differ by two amino acids between humans and chimpanzees have led to speculation that recent evolutionary changes might relate to the emergence of language. Echolocating bats face especially challenging sensorimotor demands, using vocal signals for orientation and often for prey capture. To determine whether mutations in the FoxP2 gene could be associated with echolocation, we sequenced FoxP2 from echolocating and non-echolocating bats as well as a range of other mammal species. We found that contrary to previous reports, FoxP2 is not highly conserved across all nonhuman mammals but is extremely diverse in echolocating bats. We detected divergent selection (a change in selective pressure) at FoxP2 between bats with contrasting sonar systems, suggesting the intriguing possibility of a role for FoxP2 in the evolution and development of echolocation. We speculate that observed accelerated evolution of FoxP2 in bats supports a previously proposed function in sensorimotor coordination.