Mathematics posts
- August 10, 2012
- 01:58 PM
- 383 views
Treating participants (or items) as random vs. fixed effects
by Dan Mirman in Minding the Brain
Connoisseurs of multilevel regression will already be familiar with this issue, but it is the single most common topic for questions I receive about growth curve analysis (GCA), so it seems worth discussing. The core of the issue is that in our paper about using GCA for eye tracking data (Mirman, Dixon, & Magnuson, 2008) we treated participants as fixed effects. In contrast, multilevel regression in general, and specifically the approach described by Dale Barr (2008), which is nearly identic........ Read more »
Barr D.J. (2008) Analyzing ‘visual world’ eyetracking data using multilevel logistic regression. Journal of Memory and Language, 59(4), 457. DOI: 10.1016/j.jml.2007.09.002
Gelman A. (2005) Analysis of variance -- why it is more important than ever. Annals of Statistics, 33(1), 1-33. arXiv: math/0504499v2
Henrich J., Heine S.J., & Norenzayan A. (2010) The weirdest people in the world?. The Behavioral and Brain Sciences, 33(2-3), 61-83. PMID: 20550733
Mirman D., Dixon J.A., & Magnuson J.S. (2008) Statistical and computational models of the visual world paradigm: Growth curves and individual differences. Journal of Memory and Language, 59(4), 475-494. PMID: 19060958
Mirman D., & Graziano K.M. (2012) Damage to temporo-parietal cortex decreases incidental activation of thematic relations during spoken word comprehension. Neuropsychologia, 50(8), 1990-1997. PMID: 22571932
- August 8, 2012
- 02:57 PM
- 490 views
Baby, You Light Up My World Like Nobody Else: A Guest Post
by Miss Behavior in The Scorpion and the Frog
One Direction was inspired by the brightly shining love of the bioluminescent ostracod. Photo by Fiona McKinlay at Wikimedia.by Rachel WangYou might not have guessed that the song lyrics of the band One Direction could apply to the courtship of bioluminescent marine animals, but the female ostracod crustacean (relatives of crabs and shrimp) might want to sing her heart out when she finds a bright guy to light up her world. This month's cover of the Journal of Experimental Biology feature........ Read more »
Rivers, T.J., & Morin, J.G. (2009) Plasticity of male mating behavior in a marine bioluminescent ostracod in both time and space. Animal Behavior, 78(3), 723-734. DOI: 10.1016/j.anbehav.2009.06.020
- July 23, 2012
- 12:02 PM
- 462 views
Geometry Proves Sheep Are Selfish Jerks
by Elizabeth Preston in Inkfish
Sometimes what looks like friendly behavior is really an attempt to get one's neighbor eaten by a wolf before oneself. Sheep, for instance, seem cozy enough in their flocks. What's a better way to travel than surrounded by 100 percent merino? But the real reason they stick close to their neighbors is to save their own woolly rear ends.
The question of what motivates seemingly community-minded animals is a classic one in biology. Do the birds in a flock, or the fish in a shoal, just enjoy ea........ Read more »
Andrew J. King, Alan M. Wilson, Simon D. Wilshin, John Lowe, Hamed Haddadi, Stephen Hailes, & A. Jennifer Morton. (2012) Selfish-herd behaviour of sheep under threat. Current Biology, 22(14). info:/10.1016/j.cub.2012.05.008
- July 8, 2012
- 11:00 PM
- 357 views
Critique of Chaitin’s algorithmic mutation
by Artem Kaznatcheev in Evolutionary Games Group
Last week, I reviewed Gregory Chaitin’s Proving Darwin. I concentrated on a broad overview of the book and metabiology, and did not touch on the mathematical details; This post will start touching. The goal is to summarize Chaitin’s ideas more rigorously and to address Chaitin’s comment: I disagree with your characterization of algorithmic mutations as [...]... Read more »
Chaitin, G. (2009) Evolution of Mutating Software. EATCS Bulletin, 157-164. info:/
- July 7, 2012
- 09:04 AM
- 259 views
When Data Filtering Introduces Bias
by Neuroskeptic in Neuroskeptic
Oh no. Another worrying methods problem for neuroscience, this time for electrophysiologists: Systematic biases in early ERP and ERF components as a result of high-pass filtering.The event-related potential (ERP) and event-related field (ERF) techniques provide valuable insights into the time course of processes in the brain. Researchers commonly filter the data to increase the signal-to-noise ratio. However, filtering may distort the data, leading to false results. Using our own EEG data, ........ Read more »
Acunzo DJ, Mackenzie G, & van Rossum MC. (2012) Systematic biases in early ERP and ERF components as a result of high-pass filtering. Journal of neuroscience methods. PMID: 22743800
- July 3, 2012
- 06:29 AM
- 267 views
Think twice before dropping equations to boost your citation count
by Christophe Dessimoz in Open Reading Frame
A recent PNAS article entitled "Heavy use of equations impedes communication among biologists" has caught considerable attention.In my view, the problem is not so much with their observation (equation denser papers tend to collect fewer citations) as with their main conclusion:"To maximize the scientific impact of their work, biologists should consider reducing the equation density in the main text of their theoretical articles."These type of observational analyses (i.e. *not* randomise........ Read more »
Fawcett TW, & Higginson AD. (2012) Heavy use of equations impedes communication among biologists. Proceedings of the National Academy of Sciences of the United States of America. PMID: 22733777
- July 2, 2012
- 06:06 PM
- 110 views
many, many options
by Joset Etzel in MVPA Meanderings
Let me join the chorus of people singing the praises of the recent article "False-positive psychology". If you haven't read the paper yet, go read it, especially if you don't particularly like statistics. One of the problems they highlight is "researcher degrees of freedom." In the case of MVPA I'd summarize this as having so many ways to do an analysis that if you know what sort of result you'd like you can "play around" a bit until you find one that yields what you'd like. This isn't cheating ........ Read more »
Simmons JP, Nelson LD, & Simonsohn U. (2011) False-positive psychology: undisclosed flexibility in data collection and analysis allows presenting anything as significant. Psychological science, 22(11), 1359-66. PMID: 22006061
- June 29, 2012
- 01:00 PM
- 410 views
Is Chaitin proving Darwin with metabiology?
by Artem Kaznatcheev in Evolutionary Games Group
Algorithmic information theory (AIT) allows us to study the inherent structure of objects, and qualify some as ‘random’ without reference to a generating distribution. The theory originated when Ray Solomonoff (1960), Andrey Kolmogorov (1965), and Gregory Chaitin (1966) looked at probability, statistics, and information through the algorithmic lens. Now the theory has become a central [...]... Read more »
Chaitin, G. (2009) Evolution of Mutating Software. EATCS Bulletin, 157-164. info:/
- June 28, 2012
- 11:45 AM
- 489 views
When It Comes to Numbers, We're All Late Bloomers
by Elizabeth Preston in Inkfish
Good news for aspiring jelly-bean jar estimators who are under 30! Your intuitive grasp of numbers may not have peaked yet. Unlike other cognitive skills, the ability to approximate keeps improving well into adulthood. Since the skill is tied to mathematical smarts, this news might bring hope to struggling students.
Scientists call our intuitive understanding of numbers the approximate number system, or ANS. It lets us compare amounts or guess at the size of a solution without putting our think........ Read more »
Halberda J, Ly R, Wilmer JB, Naiman DQ, & Germine L. (2012) Number sense across the lifespan as revealed by a massive Internet-based sample. Proceedings of the National Academy of Sciences of the United States of America. PMID: 22733748
- June 27, 2012
- 02:25 PM
- 431 views
Too Much Math Frightens Biologists Away
by United Academics in United Academics
Researchers from the University of Bristol, in the UK, had the suspicion that biologists didn’t like math, but they couldn’t expect how much this actually affects their work. According to their study, published in the Proceedings of the National Academy of Sciences of the United States of America, the more a study presents mathematical equations, the less it will be cited in biology papers.... Read more »
Fawcett TW, & Higginson AD. (2012) Heavy use of equations impedes communication among biologists. Proceedings of the National Academy of Sciences of the United States of America. PMID: 22733777
- June 23, 2012
- 09:30 PM
- 486 views
How would Alan Turing develop biology?
by Artem Kaznatcheev in Evolutionary Games Group
Alan Turing was born 100 years ago, today: June 23rd, 1912. He was a pioneer of computing, cryptography, artificial intelligence, and biology. His most influential work was launching computer science by the definition of computable, introduction of Turing-machine, and solution of the Entscheidungsproblem (Turing, 1936). He served his King and Country in WW2 as the [...]... Read more »
Shnerb NM, Louzoun Y, Bettelheim E, & Solomon S. (2000) The importance of being discrete: Life always wins on the surface. Proceedings of the National Academy of Sciences of the United States of America, 97(19), 10322-4. PMID: 10962027
- June 4, 2012
- 03:03 PM
- 656 views
Why You Can't Kill a Mosquito with a Raindrop
by Elizabeth Preston in Inkfish
Compared to a spindly mosquito, the mass of a raindrop is like a bus bearing down on a human. Yet the delicate insects thrive in wet, rainy climates. To find out how mosquitos live through rain showers, researchers pelted them with water drops while filming them at high speed. They saw that the insects' light weight, rather than being a liability, might be the key to their survival.
David Hu is a professor in both the biology and mechanical engineering departments at Georgia Tech. He's pre........ Read more »
Andrew K. Dickerson, Peter G. Shankles, Nihar M. Madhavan, & David L. Hu. (2012) Mosquitoes survive raindrop collisions by virtue of their low mass. PNAS. info:/10.1073/pnas.1205446109
- May 22, 2012
- 01:26 PM
- 484 views
Let the Buyer Beware
by nuclear.kelly in Miss Atomic Bomb
"Modern societies are complex systems" may be the understatement of the year. Obvious or not, however, it must be stated when attempting to model even some minuscule aspect of such a society. Take, for instance...... Read more »
Tiago P. Peixoto, & Stefan Bornholdt. (2012) No Need for Conspiracy: Self-Organized Cartel Formation in a Modified Trust Game. Physical Review Letters, 108(21), 218702. info:/10.1103/PhysRevLett.108.218702
- May 16, 2012
- 12:33 PM
- 524 views
Does Social Status Change Brains?
by Miss Behavior in The Scorpion and the Frog
Photo by The Grappling Source Inc. at Wikimedia CommonsBeing subordinated is stressful. The process of one individual lowering the social rank of another often involves physical aggression, aggressive displays, and exclusion. In addition to the obvious possible costs of being subordinated (like getting beat up), subordinated individuals often undergo physiological changes to their hormonal systems and brains. Sounds pretty scary, doesn’t it? But what if some of those changes are beneficial in ........ Read more »
Sørensen, C., Nilsson, G., Summers, C., & Øverli, �. (2012) Social stress reduces forebrain cell proliferation in rainbow trout (Oncorhynchus mykiss). Behavioural Brain Research, 227(2), 311-318. DOI: 10.1016/j.bbr.2011.01.041
Issa, F., Drummond, J., Cattaert, D., & Edwards, D. (2012) Neural Circuit Reconfiguration by Social Status. Journal of Neuroscience, 32(16), 5638-5645. DOI: 10.1523/JNEUROSCI.5668-11.2012
Yeh, S., Fricke, R., & Edwards, D. (1996) The Effect of Social Experience on Serotonergic Modulation of the Escape Circuit of Crayfish. Science, 271(5247), 366-369. DOI: 10.1126/science.271.5247.366
Issa, F., & Edwards, D. (2006) Ritualized Submission and the Reduction of Aggression in an Invertebrate. Current Biology, 16(22), 2217-2221. DOI: 10.1016/j.cub.2006.08.065
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- May 11, 2012
- 08:20 AM
- 686 views
Flat tori in 3D
It's been a while since I've read a pure math paper, but when I saw the picture I knew I had to pick this one up. For the pure mathematicians out there: I haven't done pure math since my grad years, so feel free to pitch in and correct me if I misunderstood any of the following! "Torus" is mathematics for donut. Take a very flexible square -- imagine it's made of rubber -- roll it, then glue together the circles at the two ends. Congratulations. You've made a torus. Now suppose you live on the........ Read more »
Borrelli, V., Jabrane, S., Lazarus, F., & Thibert, B. (2012) From the Cover: Flat tori in three-dimensional space and convex integration. Proceedings of the National Academy of Sciences, 109(19), 7218-7223. DOI: 10.1073/pnas.1118478109
- May 2, 2012
- 01:32 PM
- 380 views
Spurious Positive Mapping of the Brain?
by Neuroskeptic in Neuroskeptic
Many fMRI studies could be giving false-positive results according to an important new paper from Anders Eklund and colleagues: Does parametric fMRI analysis with SPM yield valid results?—An empirical study of 1484 rest datasets.The authors examined the SPM8 software package, probably the most popular tool for analyzing neuroimaging data.Their approach was beautifully simple. They wanted to check how often conventional analysis of fMRI would "find" a signal when there wasn't really anything ha........ Read more »
Eklund, A., Andersson, M., Josephson, C., Johannesson, M., & Knutsson, H. (2012) Does parametric fMRI analysis with SPM yield valid results?—An empirical study of 1484 rest datasets. NeuroImage. DOI: 10.1016/j.neuroimage.2012.03.093
- May 2, 2012
- 12:53 PM
- 646 views
Why This Horde of Idiots is No Genius
by Miss Behavior in The Scorpion and the Frog
At first look (in Part 1 of this post), swarm theory seems to predict that the larger the social group, the better the resulting group decisions and behaviors. Then, with over 300 million of us in the U.S., shouldn’t we only be making brilliant decisions? And with over 7 billion worldwide, shouldn’t we have already prevented all international conflicts, cancer, and environmental destruction? And why the heck is Snooki still everywhere we look?! A riot in Vancouver, Canada after the Vancouve........ Read more »
Seeley, T., Visscher, P., Schlegel, T., Hogan, P., Franks, N., & Marshall, J. (2011) Stop Signals Provide Cross Inhibition in Collective Decision-Making by Honeybee Swarms. Science, 335(6064), 108-111. DOI: 10.1126/science.1210361
List, C., Elsholtz, C., & Seeley, T. (2009) Independence and interdependence in collective decision making: an agent-based model of nest-site choice by honeybee swarms. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1518), 755-762. DOI: 10.1098/rstb.2008.0277
- April 30, 2012
- 03:03 PM
- 755 views
Math Shows Today's Writers Are Less Influenced by the Past
by Elizabeth Preston in Inkfish
When Charles Dickens wrote It was the of, it was the of, the immortal first words in A Tale of Two Cities, he can't have imagined that 21st-century computer scientists would parse his prepositions and pronouns as part of vast literary data sets. But today's researchers are studying the unimportant words in books to find important literary trends. With the meaty words taken out, language becomes a numbers game.
To see how literary styles evolve over time--a science dubbed "stylometr........ Read more »
James M. Hughes, Nicholas J. Foti, David C. Krakauer, & Daniel N. Rockmore. (2012) Quantitative patterns of stylistic influence in the evolution of literature. PNAS. info:/10.1073/pnas.1115407109
- April 25, 2012
- 11:54 AM
- 623 views
Can a Horde of Idiots be a Genius?
by Miss Behavior in The Scorpion and the Frog
Let’s face it: The typical individual is not that bright. Just check out these human specimens: Yet somehow, if you get enough numbskulls together, the group can make some pretty intelligent decisions. We’ve seen this in a wide variety of organisms facing a number of different challenges.In a brilliant series of studies, Jean-Louis Deneubourg, a professor at the Free University of Brussels, and his colleagues tested the abilities of Argentine ants (a common dark-brown ant ........ Read more »
Couzin, I. (2009) Collective cognition in animal groups. Trends in Cognitive Sciences, 13(1), 36-43. DOI: 10.1016/j.tics.2008.10.002
Goss, S., Aron, S., Deneubourg, J., & Pasteels, J. (1989) Self-organized shortcuts in the Argentine ant. Naturwissenschaften, 76(12), 579-581. DOI: 10.1007/BF00462870
Dussutour, A., Nicolis, S., Deneubourg, J., & Fourcassié, V. (2006) Collective decisions in ants when foraging under crowded conditions. Behavioral Ecology and Sociobiology, 61(1), 17-30. DOI: 10.1007/s00265-006-0233-x
List C, Elsholtz C, & Seeley TD. (2009) Independence and interdependence in collective decision making: an agent-based model of nest-site choice by honeybee swarms. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 364(1518), 755-62. PMID: 19073474
Dell'Ariccia, G., Dell'Omo, G., Wolfer, D., & Lipp, H. (2008) Flock flying improves pigeons' homing: GPS track analysis of individual flyers versus small groups. Animal Behaviour, 76(4), 1165-1172. DOI: 10.1016/j.anbehav.2008.05.022
- April 18, 2012
- 10:55 AM
- 595 views
It Doesn’t Always Pay to Kill Your Siblings
by Miss Behavior in The Scorpion and the Frog
A mother reed warbler feeding her "adoptive" murderous cuckoo chick. Does she really think this is her child? Photo by Per Harald Olsen on Wikimedia Commons.A woman, driven to not raise her own child, leaves her baby in another woman’s nursery, killing another baby that is there and replacing it with her own. As soon as the transplanted baby is strong enough, it slowly, methodically kills all the other children in the nursery, hording all of the adoptive mother’s attention for itself. With t........ Read more »
Gloag, R., Tuero, D., Fiorini, V., Reboreda, J., & Kacelnik, A. (2011) The economics of nestmate killing in avian brood parasites: a provisions trade-off. Behavioral Ecology, 23(1), 132-140. DOI: 10.1093/beheco/arr166
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