Tag: correlation

Cognitive flexibility and nationalism 2.0

Remember that paper about cognitive flexibility and nationalism? The one that said people who are more nationalistic in their politics tend to have lower cognitive flexibility? I’d blogged about it here. I hadn’t read the study’s paper, published in the Proceedings of the National Academy of Sciences, because I didn’t think I had to to be able to call the study’s conclusions into question. An excerpt from my previous post:

… ideological divisions, imagined in the form of political polarisation, are bad enough as it is without people on one side of the aisle being able to accuse those on the other side of having “low cognitive flexibility”. The nuance can be worded as prosaically as the neuroscientists would prefer but this won’t – can’t – stop the less-nationalistic from accusing the more-nationalistic of simply being stupid, now with a purported scientific basis.

This is why I believe something has to be off about the study. The people on the right, as it were on the political spectrum, are not stupid. They’re smart just the way those of us on the left imagine ourselves to be. Now, one defence of the study may be that it attempts to map a hallmark feature of the global political right, sort of a rampant anti-intellectualism and irrationality, to its neurological underpinnings – but nationalism is more than its endorsement of traditions or traditional values.

As it turned out: if I had, the paper would have revealed more problems with the study and made a stronger case than I was able that it is quite likely a product of the “publish or perish” kind of thinking. The reason I revisit this study now is an interesting conversation I had with Shruti Muralidhar, a cortical and hippocampal neuroscientist, currently a postdoc at the Massachusetts Institute of Technology. Before I’d written my post, I’d asked Shruti if she could read the paper and possibly critique it.

My primary concern was basically about assigning a kind of “hierarchy of cognitive abilities” to the political spectrum – that sounds dangerous. By saying the political right has less cognitive flexibility, I’d felt like the study was reaching the conclusion that there might be a purely biological explanation for why people behave the way they do. This kind of reductionism is eminently dangerous.

According to Shruti, “This understanding of the paper is not far from what they want the reader to take away – but sadly, they have little or no backing to actually prove or disprove this claim.” She summed her observation up in a few points (quoted verbatim):

  1. Cognitive flexibility is simply just that. It doesn’t mean more or less intelligence, smarts or anything like that. In fact, it might not even be a “positive” trait depending on the situation at hand.
  2. The study’s authors have administered only two cognitive tests, and one of them clearly gives counterintuitive, unexpected or, one might even say, “wrong” results, as in goes against the study’s primary hypothesis.
  3. These are correlation studies, which usually are to be taken with a bagful of salt.

The first question that arises then is why the authors – or PNAS – decided to publish their study when 50% of their tests turned in results that opposed their hypothesis: that the more nationalistic are less flexible, cognitively speaking.

She also pointed out many issues with the language in the paper, especially lines that could be misinterpreted easily. Some in particular stuck out because they revealed a deeper epistemological issue with the study.

Shruti said, “The authors clearly admit that cognitive flexibility is a multi-dimensional beast and that it is difficult to understand it completely,” and often suggest that they don’t understand it completely themselves. One giveaway is that they keep saying variations of “We need more and better tests”.

A bigger giveaway is a line on page 6: “However, it is also conceivable that immersing oneself in strongly ideological environments may encourage psychological inflexibility and promote a preference for routines and traditions.” In other words, if A stood for “more nationalistic” and B for “less cognitive flexibility”, then the authors were saying that A therefore B while also admitting that B therefore A. In other other words, their correlation was in doubt, leave alone causation. This portion concludes thus:

Nevertheless, more research is necessary to understand the nature of cognitive flexibility and the various ways in which it manifests in relation to ideological thinking.

The authors haven’t defined cognitive flexibility explicitly in their paper, instead referencing older studies on the subject. Even so, Shruti said that those papers might not be able to provide the final word either because, as one of her peers had pointed out, “Since this study is EU/Britain-specific, their idea of what ideological inflexibility is might also be different from, say, India’s or the rest of the world’s. Europe thrived on systems and thinking-within-the-box for centuries.”

All together, the paper appears to describe a study of the “low-hanging fruit” variety. Its central hypothesis has been neither proved nor disproved, the reader is left in doubt about whether the tests were properly chosen (and why more tests weren’t performed), and the paper is strewn with admissions that the authors don’t claim to understand what one of the more important keywords in the study really means.

Worst of all (to me) is that the paper has been published with a misleading headline and the university press release, with an incredibly misleading one that should take all the responsibility for fake news born as a result (and strengthening the case that they shouldn’t be trusted). And there’s quite a bit of it:

  • PsychCentral has an article that only quotes Leor Zmigrod, the lead author of the atudy and a psychologist at the University of Cambridge
  • The same is true of an article in The Guardian by Nicola Davis. The headline goes ‘Brexiters tend to dislike uncertainty and love routine, study says’ – more of the reductionism at work.
  • Andrew Brown of The Guardian takes the study’s conclusions at face value, writing in his column:

… some kinds of political argument are going to be literally interminable. Obviously this isn’t true of any particular issue. Even the question of our relations with Europe will be settled some time before the heat death of the universe. But it may be replaced by something else which arouses the same passions and splits the population in the same way, because the cognitive traits [Zmigrod] is analysing are all part of the normal variation of humanity.

In fact, it seems no prominent coverage of the paper has invited an independent researcher to comment on its findings. I concede that I myself didn’t speak to a psychologist – Shruti is a neuroscientist – but all of Shruti’s observations are hard to ignore.

Finally, if I were looking to publish a paper right now, I’d hypothesise that flattering, non-critical coverage of scientific papers – peer-reviewed or otherwise – is more common among news publishers if each paper makes it easier for the publication to maintain its political position.

Featured image credit: mwewering/pixabay.

The new and large fly the farthest

British Airways and Air France mutually retired the Concorde supersonic jet in 2003. Both companies cited rising maintenance costs as being the reason, which in turn were compounded by falling demand after the Paris crash in 2000 and a general downturn in civil aviation after 9/11. Now, American and French scientists have found that Concorde was in fact an allometric outlier that stood out design-wise at the cost of its feasibility and, presumably, its maintenance. Perhaps it grounded itself.

One thing Adrian Bejan (Duke University), J.D. Charles (Boeing) and Sylvie Lorente (Toulouse University) seem to be in awe of throughout their analysis is that the evolution of commercial airplane allometry seems deterministic (allometry is the study of the relationship between a body’s physical dimensions and its properties and functions). This is awesome because it implies that the laws of physics used to design airplanes are passively guiding the designers toward very specific solutions in spite of creative drift, and that successive models are converging toward a sort of ‘unified model’. This paradigm sounds familiar because it could be said of any engineering design enterprise, but what sets it apart is that the evolution of airplane designs appears to be mimicking the evolution of flying animals despite significant anatomical and physiological differences.

One way to look at their analysis is in terms of the parameters the scientists claim have been guiding airplane design over the years:

  1. Wingspan
  2. Fuselage length
  3. Fuel load
  4. Body size

Among them, fuel load and body size are correlated along the lines of Tsiolkovsky’s rocket equation. It says that, for rockets, if two of the following three parameters are set, the third becomes immovably fixed in a proportional way: energy expenditure against gravity, potential energy in the propellant, and the fraction of the rocket’s mass made up by the propellant. According to Bejan et al, there is a corresponding ‘airplane equation’ that shows a similar correlation between engine size, amount of fuel, and mass of the whole vehicle. The NASA explainer finds this association tyrannical because, as Paul Gilster writes,

A … rocket has to carry more and more propellant to carry the propellant it needs to carry more propellant, and so on, up the dizzying sequence of the equation

Next, there is also a correlation between wingspan and fuselage length corresponding to an economy of scale such as what exists in nature. Bejan et al find that despite dissimilarities, airplanes and birds have evolved similar allometric rules on the road to greater efficiency, and that like bigger birds, bigger airplanes are “more efficient vehicles of mass”. Based on how different airplane components have evolved over the years, the scientists were able to distill a scaling relation.

S/L ~ M1/6 g1/2 ρ1/3 σ1/4(ρaV2Cl)-3/4 21/4 Cf7/6

Be not afraid. S/L is the ratio of the wingspan to the fuselage length. It is most strongly influenced by ρa, the density; σ, the allowable stress level in the wing; g, the acceleration due to gravity; and Cf, the fixed skin-friction coefficient. More interestingly, the mass of the entire vehicle has a negligible effect on S/L, which pans out as a fixed S/L value across a range of airplane sizes.

Citation: J. Appl. Phys. 116, 044901 (2014); http://dx.doi.org/10.1063/1.4886855
Citation: J. Appl. Phys. 116, 044901 (2014); http://dx.doi.org/10.1063/1.4886855

Similarly, the size of a plane’s engine has also increased proportional to a plane’s mass. This would be common sense if not for there being a fixed, empirically determined correlation here as well: Me = 0.13M0.83, where Me and M are the masses of the engine and airplane, respectively, in tons.

During the evolution of airplanes, the engine sizes have increased almost proportionally with the airplane sizes (the data refer only to jet engine airplanes). J. Appl. Phys. 116, 044901 (2014); http://dx.doi.org/10.1063/1.4886855
During the evolution of airplanes, the engine sizes have increased almost proportionally with the airplane sizes (the data refer only to jet engine airplanes). J. Appl. Phys. 116, 044901 (2014); http://dx.doi.org/10.1063/1.4886855

In terms of these findings, the Concorde’s revolutionary design appears to have been a blip on the broader stream of traditional yet successful ones. In the words of the authors,

In chasing an “off the charts” speed rating the Concorde deviated from the evolutionary path traced by successful airplanes that preceded it. It was small, had limited passenger capacity, long fuselage, short wingspan, massive engines, and poor fuel economy relative to the airplanes that preceded it.

That the Concorde failed and that the creative drift it embodied couldn’t achieve what the uninspired rules that preceded it did isn’t to relegate the design of commercial airplanes to algorithms. It only stresses that whatever engineers have toyed with, some parameters have remained constant because they’ve had a big influence on performance. In fact, it is essentially creativity that will disrupt Bejan et al‘s meta-analysis by inventing less dense, stronger, smoother materials to build airplanes and their components with. By the analysts’ own admission, this is a materials era.

Bigger airplanes fly farther and are more efficient, and to maximize fuel efficiency, are becoming the vehicles of choice for airborne travel. And that there is a framework of allometric rules to passively maximize their inherent agency is a tribute to design’s unifying potential. In this regard, the similarity to birds persists (see chart below) as if to say there is only a fixed number of ways in which to fly better.

The characteristic speeds of all the bodies that fly, run, and swim (insects, birds, and mammals). J. Appl. Phys. 116, 044901 (2014); http://dx.doi.org/10.1063/1.4886855
The characteristic speeds of all the bodies that fly, run, and swim (insects, birds, and mammals). J. Appl. Phys. 116, 044901 (2014); http://dx.doi.org/10.1063/1.4886855

From the paper:

Equally important is the observation that over time the cloud of fliers has been expanding to the right . In the beginning were the insects, later the birds and the insects, and even later the airplanes, the birds, and the insects. The animal mass that sweeps the globe today is a weave of few large and many small. The new are the few and large. The old are the many and small.

References

The evolution of airplanes, J. Appl. Phys. 116, 044901 (2014); DOI: 10.1063/1.4886855