Perpetual motion machines do not exist

Fludd machine 1618

Robert Fludd’s description of a perpetual motion machine from the 17th Century. The idea involved water held in a tank above the apparatus driving a water wheel which, through a complex set of gears, rotate an Archimedes screw which draws the water back up to the water tank.

 


The idea of creating a machine which can continue indefinitely without any source of energy to power it is one that has fascinated inventors since the astronomer and mathematician Bhāskara II described a wheel which could run forever in the 12th century. The failure to build such a machine hasn’t stopped people from trying to build them or even applications for patent; whether using magnets, or gravity or buoyancy as the basis for perpetual motion. However, no attempt to create one has ever worked.

Perpetual motion machines do not exist, because no one has built a machine which can continue indefinitely without some external source of energy to keep it going.

It would be very, very odd for someone to claim that they did exist, simply because inventors periodically try to create one. I’d certainly accept that they have tried to create a perpetual motion machine (and thus far failed), or created a machine which they claimed possessed perpetual motion (but didn’t really) – but to say that perpetual motion machines ‘exist’ surely implies that someone has built one that actually works.

I recently read a short series of blogs defending the idea of ‘learning styles’. The idea at the heart of learning styles is that information provided to a student in a form that matches their ‘style of learning’ will lead to improved learning.

Coffield et al (2004) review over a dozen attempts to measure differences in learning ability so that instruction can be matched to this ‘style of learning’. Certainly, all of the systems have tried to define learning styles, but the question is whether any of them actually work. They found that whilst a few of the them provided some relatively valid measures of differences between people, none of them demonstrated that attempting to match teaching to this style would have any benefit.

They conclude that whilst learning style theorists have conducted small-scale, weakly controlled studies to support their claims, none of them produce systems with any clear evidence that using them will advantage learners. None of the proposed systems work.

Pashler et al (2008) helpfully define what a learning style is supposed to be.

“The term ‘‘learning styles’’ refers to the concept that individuals differ in regard to what mode of instruction or study is most effective for them. Proponents of learning-style assessment contend that optimal instruction requires diagnosing individuals’ learning style and tailoring instruction accordingly.”

This makes it clear that merely identifying some differences in people isn’t sufficient for the label of a ‘learning style’ to be applied. As well as being able to measure some sort of psychometrically reliable differences, a learning style also needs to show what mode of instruction would be most effective for an individual. They also note that very few studies have actually tested whether proposed learning styles actually improve learning when instruction is tailored to them. Where these studies have been conducted, several found results which contradicted their claims. The data so far do not support the idea of learning styles.

No attempt at ‘learning styles’ has ever succeeded. It would seem bizarre, therefore, to claim that learning styles exist. I’d certainly accept that people have tried to describe learning styles (and failed) or that some people claim a system of learning styles is effective (when they don’t have evidence to support that view).

Cognitive scientists like Daniel Willingham and teachers like Tom Bennett seem on pretty safe ground making the claim that they don’t exist. The burden of proof is on those claiming that learning styles exist – let them produce the data showing both valid measures which differentiate learners and that matching instruction to these differences enhances learning. If robust evidence to support this comes to light in the future, then I am certain both would change their position (as would I) – that’s the nature of science.

In the meantime, however, claiming that ‘learning styles exist’ smacks almost of what Irving Langmuir called pathological science: ‘an area of research where “people are tricked into false results … by subjective effects, wishful thinking or threshold interactions”’. Langmuir identified pathological science, like perpetual motion machines, as fruitless ideas that simply will not “go away” despite repeated failure.

Given that attempts to identify effective learning styles is hardly new (at least since the 1980s), I have sympathy with the frustration in this article by Tom Bennett which argues that VAK – the most notorious attempt at learning styles in UK education –  is a ‘zombie’ idea in education that simply fails to die.

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12 Responses to Perpetual motion machines do not exist

  1. You say Pashler et al ‘helpfully define what a learning style is supposed to be’.

    There is a problem at the heart of any conceptual construct, and that is that people use constructs and the labels for them, in subtly (sometimes not so subtly) different ways. Those differences create a headache for researchers and can sometimes result in research being stuck in a theoretical cul-de-sac for decades.

    Some people have got so fed up with the idea of ‘definitions’ or what constructs are ‘supposed to be’ – they’ve abandoned the idea entirely and instead refer to how a construct/word is used. Pashler et al’s ‘definition’ is a fair summary of how the term ‘learning styles’ is used, but it doesn’t help operationalise the metrics in any given learning style model.

    You point out that Pashler et al “note that very few studies have actually tested whether proposed learning styles actually improve learning when instruction is tailored to them”. That’s a significant problem with the evidence. If few studies have tested that hypothesis, we can’t conclude much about the existence of learning styles – one way or the other.

    I agree that the burden of proof is on those claiming that learning styles *do* exist, but the absence of such evidence doesn’t warrant the conclusion that learning styles *don’t* exist, any more than it would have been safe to conclude that microscopic organisms or subatomic particles didn’t exist, in the days when evidence for them was a bit thin on the ground.

    More than one review paper has concluded that the weakness of the evidence doesn’t warrant teachers investing time or effort in carrying out learning styles assessments. Why not simply reiterate that conclusion? Why focus so intently on whether learning styles ‘exist’ or not? Why is that so important?

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    • “I agree that the burden of proof is on those claiming that learning styles *do* exist, but the absence of such evidence doesn’t warrant the conclusion that learning styles *don’t* exist,”

      Perhaps it’s my background in parapsychology that inclines my view here. Given that this same argument is used to support ESP or telekinesis; alien visitations and abductions; the existence of ghosts and fairies – I don’t find it especially convincing. In the absence of evidence to support their existence – why should I believe they exist?

      However, when some evidence comes to light that matching instruction to valid psychometric differences reliably improves learning – I’ll happily accept that learning styles exist. Until then, especially given the damage done by labelling children using the failed system of VAK, I’ll continue to hold the view that they do not.

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      • But that’s not how science works. It works by eliminating what’s false, not by proving what’s true.

        In the case of parapsychological phenomena there is no reason why you should believe that they exist, but you have no grounds to conclude that they don’t exist either.

        I don’t understand why one has to take a position on the existence of things – why not just keep an open mind and go only as far as the evidence allows?

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  2. Actually, Karl Popper might argue that it is precisely how science works. The evidence doesn’t show support for the existence of learning styles. A hypothesis may be falsified if a key predicted observation (i.e. that matching instruction to differences improves learning) is not found empirically. When a hypothesis is proposed and the evidence supports the null hypothesis, you abandon that hypothesis.

    After thought: I’ve clearly stated what evidence would convince me that learning styles exist. Can you outline what evidence would convince you that learning styles don’t exist?

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  3. Chester Draws says:

    Another principal of science is Occam’s Razor — basically the simplest explanation is usually the best. You can’t posit something by using unknown mechanisms for example without very good evidence for those unknown mechanisms.

    If learning styles exist then there must be a mechanism and the only logical place for that is genetic — what other options do we have? (If learning styles are non-genetic they must be learned. And if they are learned, then they can be taught over.)

    If different races cannot be shown to learn differently, on the basis that they are as different as people can be genetically, then the chance that inter-racial differences exist is basically zero.

    There is some strong evidence that some races are actually better at learning some things than others, although current political tendencies generally doesn’t allow people to say that. But I’ve seen nothing that shows they learn differently. Until that comes along, learning styles seems a fad to explain learned personal preferences.

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    • I think it’s human nature to concentrate on the apparent differences between people (or groups of people) rather than the similarities. In education, I don’t think that focus is terribly helpful – as the things children have in common about the way they learn are likely much more profitable areas to explore in our teaching than trying to define differences in the way children learn and adapt teaching to these.

      For example: The recent Deans for Impact summary of the science for learning: https://evidenceintopractice.wordpress.com/2015/10/02/the-science-of-learning/ outlines commonalities in the way that children learn. If teachers can implement these ideas successfully, these are much more likely to lead to gains in children’s learning than anything cooked up in the name of ‘learning styles’.

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  4. Throwcase says:

    It seems obvious to me that there are styles of learning, insofar as we could truthfully say that everybody learns differently because everybody is different. Whether that means there are quantifiable “learning styles” is a different matter altogether.

    In my student years I felt a strong difference between the way I needed to learn compared to some of my friends. In one case, I needed to teach someone how to use a computer, but we each approached it in a different way- I needed to know the process kinesthetically, by doing, but they needed to know it conceptually, with flowcharts and diagrams etc. neither could appreciate the other’s “learning style.”

    As a musician this also comes out in various ways. Some pianists I know learn visually, such that if they learn a piece with one edition it is then very difficult for them to play it from another edition, due to the different visual layout. Others learn much more theoretically, and the visual layout of each edition makes less impact to them. With that being said, turning this into a definable “learning style” would be very difficult, as the lines are fluid and ever changing. I used to be a visual learner, but over time I have become very used to changing editions, simply as a professional necessity.

    I doubt it woild be possible to quantify and delineate a set of universal learning styles, though I’m sure theybso in fact exist. I would conclude by saying there are probably as many learning styles as there are people.

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