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Why schools should not teach general critical-thinking skills
Schools have become captivated by the idea that students must learn a set of generalized critical-thinking skills to flourish in the contemporary world.
At the heart of the job is a cognitive ability called 'situational awareness' that involves 'the continuous extraction of environmental information [and the] integration of this information with prior knowledge to form a coherent mental picture'. Vast amounts of fluid information must be held in the mind and, under extreme pressure, life-or-death decisions are made across rotating 24-hour work schedules. So stressful and mentally demanding is the job that, in most countries, air-traffic controllers are eligible for early retirement. In the United States, they must retire at 56 without exception.
In the 1960s, an interesting series of experiments was done on air-traffic controllers' mental capacities. Researchers wanted to explore if they had a general enhanced ability to 'keep track of a number of things at once' and whether that skill could be applied to other situations. After observing them at their work, researchers gave the air-traffic controllers a set of generic memory-based tasks with shapes and colours. The extraordinary thing was that, when tested on these skills outside their own area of expertise, the air-traffic controllers did no better than anyone else. Their remarkably sophisticated cognitive abilities did not translate beyond their professional area.
Since the early 1980s, however, schools have become ever more captivated by the idea that students must learn a set of generalised thinking skills to flourish in the contemporary world – and especially in the contemporary job market. Variously called '21st-century learning skills' or 'critical thinking', the aim is to equip students with a set of general problem-solving approaches that can be applied to any given domain; these are lauded by business leaders as an essential set of dispositions for the 21st century. Naturally, we want children and graduates to have a set of all-purpose cognitive tools with which to navigate their way through the world. It's a shame, then, that we've failed to apply any critical thinking to the question of whether any such thing can be taught.
As the 1960s studies on air-traffic controllers suggested, to be good in a specific domain you need to know a lot about it: it's not easy to translate those skills to other areas. This is even more so with the kinds of complex and specialised knowledge that accompanies much professional expertise: as later studies found, the more complex the domain, the more important domain-specific knowledge. This non-translatability of cognitive skill is well-established in psychological research and has been replicated many times. Other studies, for example, have shown that the ability to remember long strings of digits doesn't transfer to the ability to remember long strings of letters. Surely we're not surprised to hear this, for we all know people who are 'clever' in their professional lives yet who often seem to make stupid decisions in their personal lives.
In almost every arena, the higher the skill level, the more specific the expertise is likely to become. In a football team, for example, there are different 'domains' or positions: goalkeeper, defender, attacker. Within those, there are further categories: centre-back, full-back, attacking midfielder, holding midfielder, attacking player. Now, it might be fine for a bunch of amateurs, playing a friendly game, to move positions. But, at a professional level, if you put a left-back in a striker's position or a central midfielder in goal, the players would be lost. For them to make excellent, split-second decisions, and to enact robust and effective strategies, they need thousands of specific mental models – and thousands of hours of practice to create those models – all of which are specific and exclusive to a position.
Of course, critical thinking is an essential part of a student's mental equipment. However, it cannot be detached from context. Teaching students generic 'thinking skills' separate from the rest of their curriculum is meaningless and ineffective. As the American educationalist Daniel Willingham puts it:
[I]f you remind a student to 'look at an issue from multiple perspectives' often enough, he will learn that he ought to do so, but if he doesn't know much about an issue, he can't think about it from multiple perspectives … critical thinking (as well as scientific thinking and other domain-based thinking) is not a skill. There is not a set of critical thinking skills that can be acquired and deployed regardless of context.
This detachment of cognitive ideals from contextual knowledge is not confined to the learning of critical thinking. Some schools laud themselves for placing '21st-century learning skills' at the heart of their mission. It's even been suggested that some of these nebulous skills are now as important as literacy and should be afforded the same status. An example of this is brain-training games that claim to help kids become smarter, more alert and able to learn faster. However, recent research has shown that brain-training games are really only good for one thing – getting good a brain-training games. The claim that they offer students a general set of problem-solving skills was recently debunked by a study that reviewed more than 130 papers, which concluded:
[W]e know of no evidence for broad-based improvement in cognition, academic achievement, professional performance, and/or social competencies that derives from decontextualised practice of cognitive skills devoid of domain-specific content.
The same goes for teaching 'dispositions' such as the 'growth mindset' (focusing on will and effort as opposed to inherent talent) or 'grit' (determination in the face of obstacles). It's not clear that these dispositions can be taught, and there's no evidence that teaching them outside a specific subject matter has any effect.
Instead of teaching generic critical-thinking skills, we ought to focus on subject-specific critical-thinking skills that seek to broaden a student's individual subject knowledge and unlock the unique, intricate mysteries of each subject. For example, if a student of literature knows that Mary Shelley's mother died shortly after Mary was born and that Shelley herself lost a number of children in infancy, that student's appreciation of Victor Frankenstein's obsession with creating life from death, and the language used to describe it, is more enhanced than approaching the text without this knowledge. A physics student investigating why two planes behave differently in flight might know how to 'think critically' through the scientific method but, without solid knowledge of contingent factors such as outside air temperature and a bank of previous case studies to draw upon, the student will struggle to know which hypothesis to focus on and which variables to discount.
As Willingham writes: 'Thought processes are intertwined with what is being thought about.' Students need to be given real and significant things from the world to think with and about, if teachers want to influence how they do that thinking.
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Why mega-eruptions like the ones that covered North America in ash are the least of your worries.
- The supervolcano under Yellowstone produced three massive eruptions over the past few million years.
- Each eruption covered much of what is now the western United States in an ash layer several feet deep.
- The last eruption was 640,000 years ago, but that doesn't mean the next eruption is overdue.
The end of the world as we know it
Panoramic view of Yellowstone National Park
Image: Heinrich Berann for the National Park Service – public domain
Of the many freak ways to shuffle off this mortal coil – lightning strikes, shark bites, falling pianos – here's one you can safely scratch off your worry list: an outbreak of the Yellowstone supervolcano.
As the map below shows, previous eruptions at Yellowstone were so massive that the ash fall covered most of what is now the western United States. A similar event today would not only claim countless lives directly, but also create enough subsidiary disruption to kill off global civilisation as we know it. A relatively recent eruption of the Toba supervolcano in Indonesia may have come close to killing off the human species (see further below).
However, just because a scenario is grim does not mean that it is likely (insert topical political joke here). In this case, the doom mongers claiming an eruption is 'overdue' are wrong. Yellowstone is not a library book or an oil change. Just because the previous mega-eruption happened long ago doesn't mean the next one is imminent.
Ash beds of North America
Ash beds deposited by major volcanic eruptions in North America.
Image: USGS – public domain
This map shows the location of the Yellowstone plateau and the ash beds deposited by its three most recent major outbreaks, plus two other eruptions – one similarly massive, the other the most recent one in North America.
The Huckleberry Ridge eruption occurred 2.1 million years ago. It ejected 2,450 km3 (588 cubic miles) of material, making it the largest known eruption in Yellowstone's history and in fact the largest eruption in North America in the past few million years.
This is the oldest of the three most recent caldera-forming eruptions of the Yellowstone hotspot. It created the Island Park Caldera, which lies partially in Yellowstone National Park, Wyoming and westward into Idaho. Ash from this eruption covered an area from southern California to North Dakota, and southern Idaho to northern Texas.
About 1.3 million years ago, the Mesa Falls eruption ejected 280 km3 (67 cubic miles) of material and created the Henry's Fork Caldera, located in Idaho, west of Yellowstone.
It was the smallest of the three major Yellowstone eruptions, both in terms of material ejected and area covered: 'only' most of present-day Wyoming, Colorado, Kansas and Nebraska, and about half of South Dakota.
The Lava Creek eruption was the most recent major eruption of Yellowstone: about 640,000 years ago. It was the second-largest eruption in North America in the past few million years, creating the Yellowstone Caldera.
It ejected only about 1,000 km3 (240 cubic miles) of material, i.e. less than half of the Huckleberry Ridge eruption. However, its debris is spread out over a significantly wider area: basically, Huckleberry Ridge plus larger slices of both Canada and Mexico, plus most of Texas, Louisiana, Arkansas, and Missouri.
This eruption occurred about 760,000 years ago. It was centered on southern California, where it created the Long Valley Caldera, and spewed out 580 km3 (139 cubic miles) of material. This makes it North America's third-largest eruption of the past few million years.
The material ejected by this eruption is known as the Bishop ash bed, and covers the central and western parts of the Lava Creek ash bed.
Mount St Helens
The eruption of Mount St Helens in 1980 was the deadliest and most destructive volcanic event in U.S. history: it created a mile-wide crater, killed 57 people and created economic damage in the neighborhood of $1 billion.
Yet by Yellowstone standards, it was tiny: Mount St Helens only ejected 0.25 km3 (0.06 cubic miles) of material, most of the ash settling in a relatively narrow band across Washington State and Idaho. By comparison, the Lava Creek eruption left a large swathe of North America in up to two metres of debris.
The difference between quakes and faults
The volume of dense rock equivalent (DRE) ejected by the Huckleberry Ridge event dwarfs all other North American eruptions. It is itself overshadowed by the DRE ejected at the most recent eruption at Toba (present-day Indonesia). This was one of the largest known eruptions ever and a relatively recent one: only 75,000 years ago. It is thought to have caused a global volcanic winter which lasted up to a decade and may be responsible for the bottleneck in human evolution: around that time, the total human population suddenly and drastically plummeted to between 1,000 and 10,000 breeding pairs.
Image: USGS – public domain
So, what are the chances of something that massive happening anytime soon? The aforementioned mongers of doom often claim that major eruptions occur at intervals of 600,000 years and point out that the last one was 640,000 years ago. Except that (a) the first interval was about 200,000 years longer, (b) two intervals is not a lot to base a prediction on, and (c) those intervals don't really mean anything anyway. Not in the case of volcanic eruptions, at least.
Earthquakes can be 'overdue' because the stress on fault lines is built up consistently over long periods, which means quakes can be predicted with a relative degree of accuracy. But this is not how volcanoes behave. They do not accumulate magma at constant rates. And the subterranean pressure that causes the magma to erupt does not follow a schedule.
What's more, previous super-eruptions do not necessarily imply future ones. Scientists are not convinced that there ever will be another big eruption at Yellowstone. Smaller eruptions, however, are much likelier. Since the Lava Creek eruption, there have been about 30 smaller outbreaks at Yellowstone, the last lava flow being about 70,000 years ago.
As for the immediate future (give or take a century): the magma chamber beneath Yellowstone is only 5 percent to 15 percent molten. Most scientists agree that is as un-alarming as it sounds. And that its statistically more relevant to worry about death by lightning, shark, or piano.
Strange Maps #1041
Got a strange map? Let me know at firstname.lastname@example.org.
The potential of CRISPR technology is incredible, but the threats are too serious to ignore.
- CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a revolutionary technology that gives scientists the ability to alter DNA. On the one hand, this tool could mean the elimination of certain diseases. On the other, there are concerns (both ethical and practical) about its misuse and the yet-unknown consequences of such experimentation.
- "The technique could be misused in horrible ways," says counter-terrorism expert Richard A. Clarke. Clarke lists biological weapons as one of the potential threats, "Threats for which we don't have any known antidote." CRISPR co-inventor, biochemist Jennifer Doudna, echos the concern, recounting a nightmare involving the technology, eugenics, and a meeting with Adolf Hitler.
- Should this kind of tool even exist? Do the positives outweigh the potential dangers? How could something like this ever be regulated, and should it be? These questions and more are considered by Doudna, Clarke, evolutionary biologist Richard Dawkins, psychologist Steven Pinker, and physician Siddhartha Mukherjee.
Measuring a person's movements and poses, smart clothes could be used for athletic training, rehabilitation, or health-monitoring.
In recent years there have been exciting breakthroughs in wearable technologies, like smartwatches that can monitor your breathing and blood oxygen levels.
But what about a wearable that can detect how you move as you do a physical activity or play a sport, and could potentially even offer feedback on how to improve your technique?
And, as a major bonus, what if the wearable were something you'd actually already be wearing, like a shirt of a pair of socks?
That's the idea behind a new set of MIT-designed clothing that use special fibers to sense a person's movement via touch. Among other things, the researchers showed that their clothes can actually determine things like if someone is sitting, walking, or doing particular poses.
The group from MIT's Computer Science and Artificial Intelligence Lab (CSAIL) says that their clothes could be used for athletic training and rehabilitation. With patients' permission, they could even help passively monitor the health of residents in assisted-care facilities and determine if, for example, someone has fallen or is unconscious.
The researchers have developed a range of prototypes, from socks and gloves to a full vest. The team's "tactile electronics" use a mix of more typical textile fibers alongside a small amount of custom-made functional fibers that sense pressure from the person wearing the garment.
According to CSAIL graduate student Yiyue Luo, a key advantage of the team's design is that, unlike many existing wearable electronics, theirs can be incorporated into traditional large-scale clothing production. The machine-knitted tactile textiles are soft, stretchable, breathable, and can take a wide range of forms.
"Traditionally it's been hard to develop a mass-production wearable that provides high-accuracy data across a large number of sensors," says Luo, lead author on a new paper about the project that is appearing in this month's edition of Nature Electronics. "When you manufacture lots of sensor arrays, some of them will not work and some of them will work worse than others, so we developed a self-correcting mechanism that uses a self-supervised machine learning algorithm to recognize and adjust when certain sensors in the design are off-base."
The team's clothes have a range of capabilities. Their socks predict motion by looking at how different sequences of tactile footprints correlate to different poses as the user transitions from one pose to another. The full-sized vest can also detect the wearers' pose, activity, and the texture of the contacted surfaces.
The authors imagine a coach using the sensor to analyze people's postures and give suggestions on improvement. It could also be used by an experienced athlete to record their posture so that beginners can learn from them. In the long term, they even imagine that robots could be trained to learn how to do different activities using data from the wearables.
"Imagine robots that are no longer tactilely blind, and that have 'skins' that can provide tactile sensing just like we have as humans," says corresponding author Wan Shou, a postdoc at CSAIL. "Clothing with high-resolution tactile sensing opens up a lot of exciting new application areas for researchers to explore in the years to come."
The paper was co-written by MIT professors Antonio Torralba, Wojciech Matusik, and Tomás Palacios, alongside PhD students Yunzhu Li, Pratyusha Sharma, and Beichen Li; postdoc Kui Wu; and research engineer Michael Foshey.
The work was partially funded by Toyota Research Institute.