IELTS Academic Reading Practice Test 490

Few seabirds are as familiar, or as frequently photographed, as the Atlantic puffin (Fratercula arctica). It belongs to the auk family, whose other members include the guillemot and the razorbill, and it shares their upright stance and their preference for steep, wind-battered coasts. Its black back, white belly, orange legs and heavy triangular bill have earned it the nickname 'sea parrot', while its solemn expression and clumsy walk have led others to call it the clown of the sea. The species is confined to the North Atlantic; the two other members of the genus live in the North Pacific.

The bill is the bird's most striking feature and also its most misunderstood. In the breeding season the outer plates are vivid orange, with yellow ridges and a slate-blue band near the base. After the young have left, the bird sheds these outer layers, together with the bright rosette at the corner of the mouth, and the bill shrinks to a smaller, duller structure for the winter. This annual change, which takes several weeks, is one reason why photographs of puffins can look like pictures of different species.

Puffins spend the winter at sea and come ashore only to breed, arriving at their colonies from late spring. A colony may contain tens of thousands of pairs, packed so tightly that the ground appears to move. Each pair occupies a burrow, which the birds excavate with their bills and their feet, or a crevice among rocks where digging is impossible. A burrow may run a metre or more into the slope and ends in a chamber lined with grass and feathers. Puffins are remarkably faithful to these sites: a bird that has bred successfully will usually return to the same burrow, and often to the same partner, the following year.

The single egg, which is white and faintly marked, is laid in the chamber at the end of the burrow. Both birds take turns to incubate it, holding it against a bare patch of skin on the belly, and the changeover is often accompanied by noisy greeting. Incubation lasts about forty days, roughly six weeks. When the chick hatches it is covered in soft dark down and cannot regulate its own temperature, so one parent remains with it while the other goes to sea.

Food is brought back in the bill, and the puffin's method of carrying it is unusually efficient. The tongue is rough and edged with backward-pointing spines, and the upper bill is serrated near the tip; together they allow a bird to hold a row of small fish crosswise while continuing to catch more. Sandeels, sprats, herring and capelin are the main prey, the mixture varying with season and colony. In some places a single delivery may contain dozens of fish, arranged head to tail, which explains how a pair can raise a chick on relatively few visits to land.

The chick, known on many islands as a puffling, stays underground for around six weeks. It then leaves the burrow, but not in daylight and not by air. Unable to fly, it emerges under cover of darkness, when the gulls and skuas that patrol the colony are less active, and makes its way to the sea, sometimes walking, sometimes fluttering downhill, sometimes swimming out from a ledge. It will not return to land for several years.

In the air the puffin is a fast, direct flier but an ungainly one. Its wings are short and narrow, an adaptation to life underwater rather than above it, and it must beat them roughly 400 times a minute to stay aloft. Take-off from the sea requires a long run across the surface, feet pattering, until enough speed has been built up. Beneath the waves the same wings are used to 'fly' in pursuit of fish, and the bird can stay submerged for half a minute or more, steering with its feet.

Once the breeding season is over, puffins disperse widely and are rarely seen from land. Ringing studies, in which numbered metal bands are attached to the legs of nestlings, have shown that the birds can live for decades; individuals have been recorded breeding more than twenty years after they were first marked. Where they go in winter was for a long time a mystery, and only with the development of small electronic tracking devices have researchers begun to map the feeding areas used by different colonies.

The species is exposed to a combination of pressures. The most serious is the availability of food. Sandeels depend on plankton, and rising sea temperatures have shifted the timing and location of plankton blooms, so that chicks may hatch when their prey is scarce; colonies in the North Sea have suffered particularly poor breeding seasons as a result. On land, rats and mink brought to islands by ships take eggs and young, and burrows are easily crushed by grazing animals.

For these reasons the Atlantic puffin is classified as Vulnerable on the IUCN Red List, although its global population remains large and the picture is uneven: some colonies are growing while others have collapsed. Protection of nesting islands, limits on hunting in Iceland and the Faroe Islands, where the bird is still taken for food, and monitoring of food supplies all form part of current efforts. The bird's popularity is itself an asset, since few species attract so many paying visitors to remote places.

Look at the room around you and it seems to be reproduced inside your head in perfect detail. It is not. The information that reaches the brain from the eyes is fragmentary, noisy and delayed, and much of the visual field is never sampled at all. The most obvious gap is the blind spot, the point where the optic nerve leaves each eye. Because there are no light-sensitive cells there, a small region of the world is missing from every image, yet nobody sees a hole. Something fills it in.

The blind spot is not a minor curiosity. It occupies a surprisingly large part of the visual field, roughly the size of a large coin held at arm's length, and it lies close to the centre of vision. Normally the two eyes cover for each other, but even with one eye closed the gap is invisible. In experiments, patterns have been projected so that part of the image fell inside the blind area. Subjects did not report a blank; they reported the pattern continuing across it, complete with the colour and texture of its surroundings.

Filling in the blind spot is only one example of a much broader phenomenon. Perception, according to a growing body of evidence, is largely a matter of prediction. The brain is not a passive receiver of signals; it is constantly generating a model of what is probably out there, based on past experience, and using the senses to correct that model when it goes wrong. The nineteenth-century physician Hermann von Helmholtz called the process 'unconscious inference', and the phrase captures the idea well: the brain draws conclusions that we never explicitly reason through.

Sound offers a striking illustration. In the 1970s the psychologist Richard Warren played volunteers a recording of a sentence in which a brief cough had replaced one of the speech sounds. The sentence still made sense, and listeners were asked when the cough had occurred and what sound it had covered. Most were unable to say precisely where the interruption had been; several insisted that the missing sound was audible, even though the recording contained no trace of it. The brain, it seems, prefers a coherent message to an accurate record.

Vision is subject to similar editing. The eyes move several times a second in rapid jerks, and during each movement the image on the retina is smeared; the brain suppresses the blur and stitches the fragments into a stable scene. This economy has a price. In a well-known demonstration, volunteers watching a short film of students passing basketballs were asked to count the passes and mostly failed to notice a person in a gorilla suit walking through the middle of the scene. In another, an experimenter who had stopped a pedestrian to ask for directions was replaced by a different person carrying a door, and about half of the pedestrians noticed nothing.

The same preference for coherence shapes memory. When people recall a story, they tend to tidy it: unfamiliar details are dropped, familiar ones are added, and the whole is bent towards what the rememberer already believes. The classic demonstration was carried out by the psychologist Frederic Bartlett in the 1930s, using a North American folk tale that he read to English students. Repeated retellings quietly turned the story into something closer to an English reader's expectations.

None of this is a design fault. A system that waited for complete information would be too slow to be useful, and predicting is far cheaper than processing every detail. The strategies involved also help to explain everyday competence: a familiar face is recognised in poor light, a word is understood in a noisy room, a driver anticipates a cyclist's movement before there is any clear signal of it. The brain's readiness to complete a pattern allows it to act quickly on limited evidence, which is exactly what survival usually demands.

The costs, though, are real. If expectation can create a perception, it can also distort one. Researchers who study hallucinations argue that some of them arise when the brain's predictions become unusually strong and the corrective sensory evidence unusually weak, so that the model dominates. The intuition is captured by the phrase 'seeing is believing', which, in this account, runs backwards more often than we care to admit. Perceptual illusions, too, are not failures of the eye but consequences of assumptions that normally serve us well.

How literally the brain fills a gap remains disputed. One view holds that the visual system genuinely constructs the missing content, so that the blind area is represented as though it had been seen. Another argues that nothing is constructed; the brain simply fails to notice that something is absent, in the same way that a missing brick may go unremarked if the wall looks sound. The two explanations can be hard to distinguish, because in both cases the person reports a complete scene. Which is correct is still a matter of argument.

Whatever the answer, the broader lesson is unlikely to change. Perception is an act of construction, performed continuously and without effort, in which what we know and what we expect are as important as what our eyes and ears actually receive. The gaps, it turns out, are filled so smoothly that we rarely suspect that they were ever there, and the world we experience is a working model rather than a photograph.

Few public policies affect as many people for as long as the financing of higher education. In most wealthy countries the cost of a degree is now shared between the state and the student, and the practical question is how the student's share should be paid. One answer has spread widely over the past three decades: an income-contingent loan, repaid through the tax system once the graduate's earnings pass a certain level. The arrangement sounds technical, but the arguments about it are really arguments about fairness.

Australia was the pioneer. Its higher education contribution scheme, introduced in 1989, allowed students to defer their fees and repay them later through the tax office, with the obligation calculated as a proportion of income rather than as a fixed instalment. England, New Zealand and several other systems adopted variations of the same idea. The essential feature is that repayment is contingent: it rises and falls with what the graduate actually earns, and stops altogether when earnings fall below a threshold.

The case in favour rests on insurance. A student cannot know whether a degree in a subject they love will lead to a well-paid job, and a system of fixed repayments punishes those whose gamble fails. If repayments cease when income is low, the risk is shared with the state, which can borrow more cheaply than an individual and can spread losses across millions of former students. Collection through the tax system is also cheap, because employers already withhold income tax: there is no separate bill, no reminder, and very little scope for default.

The case against is less obvious but, in my view, more interesting. Withholding a proportion of income above a threshold is, in effect, an additional tax on precisely the people the system is meant to help. A graduate earning just above the repayment threshold may keep only a fraction of any pay rise, because the extra income attracts income tax, social insurance and the loan repayment together. Economists call the result an effective marginal tax rate, and in several countries it can exceed fifty per cent for graduates in mid-career. A system designed to insure against low earnings thus penalises the attempt to rise above them.

There is a second objection, which concerns access rather than incentives. Because repayment is contingent, graduates who earn little never repay much, so in theory the scheme should deter nobody. A growing body of evidence suggests, however, that price signals reach people long before the details of repayment do. Students from families with no experience of university often compare the headline figure of the debt with the earnings they expect, and some are discouraged by a sum that in practice they would never have repaid in full. Debt aversion of this kind has been documented in several countries, and the number of applicants from poorer backgrounds has not risen as quickly as the designers of these schemes expected.

There is also a question of principle. Graduates earn more, on average, than people who did not go to university, and it is reasonable that they should contribute more towards the cost of the education that helped them to do so. On this argument, repayment through the tax system is simply a way of collecting a fair contribution without demanding money that a young adult does not yet have. Those who object often overlook how much of the cost is never recovered at all: in England, for example, a large share of the money lent is expected to be written off.

That write-off is where the accounting becomes politically convenient. A loan appears in the public accounts as an asset, while the part that will never be repaid is a cost that appears years later, or, in some presentations, hardly appears at all. A government that wishes to look generous today can lend money and let a future administration absorb the loss. Several economists have argued that the expected subsidy should be shown openly in the year it is granted, so that voters can see what a scheme actually costs.

Collection through the tax system also depends on the tax system catching the graduate. Those who emigrate can be difficult to trace, and although some countries require former students to declare their overseas income and continue paying, enforcement is uneven. The sums involved are small in any single case and awkward to pursue across borders, so the most mobile graduates, who are often the highest earners, may contribute least.

My own view is that repayment through the tax system is the least unsatisfactory method available, but only if three conditions are met. The rate of interest charged on the loan should not exceed the government's own cost of borrowing; anything above that turns an insurance scheme into a profit-making one. The threshold at which repayment begins should be tied to the earnings of a typical worker rather than frozen in cash terms. And the information given to prospective students should state plainly how much of the money is likely to be repaid and how much written off.

Even then, the length of the repayment period deserves scrutiny. A commitment lasting thirty years follows graduates into middle age, reducing their capacity to save, to borrow for a home or to work shorter hours when their children are young. The question is not whether graduates should pay something towards a degree from which they benefit. It is how the payment is structured, and whether the structure is honest about who pays.